Before you start tearing down the carb, check the idle tubes. I'm sure Bill
can provide a link. I went through SEVEN carbs on my 87 YJ before I gave up
on the 'professionals' and crawled back under the hood.

"bobvonbob" <bennettvonbennett@gmail.com> wrote in message
news:1143172476.319368.121040@i40g2000cwc.googlegr oups.com...
> thanks bill - i'll try the choke pull-off!
>
> i have a slight problem with a lack of avail. workspace - nowhere to
> soak parts, no compressor to blow out ports, etc - also this sucker is
> soon to be my only vehicle so time is of the essence - all that said:
> d'ya think its better to attempt to rebuild the carb myself or to by a
> rebuilt one from NAPA or wherever..
> .
> also any good links for getting rid of this Carter and switching to a
> Weber? i've seen this mentioned and am curious....
>
> thanks and i'll post and mention whether the choke pull-off replacement
> has any effect...
> bennett
>

 

Before you start tearing down the carb, check the idle tubes. I'm sure Bill
can provide a link. I went through SEVEN carbs on my 87 YJ before I gave up
on the 'professionals' and crawled back under the hood.

"bobvonbob" <bennettvonbennett@gmail.com> wrote in message
news:1143172476.319368.121040@i40g2000cwc.googlegr oups.com...
> thanks bill - i'll try the choke pull-off!
>
> i have a slight problem with a lack of avail. workspace - nowhere to
> soak parts, no compressor to blow out ports, etc - also this sucker is
> soon to be my only vehicle so time is of the essence - all that said:
> d'ya think its better to attempt to rebuild the carb myself or to by a
> rebuilt one from NAPA or wherever..
> .
> also any good links for getting rid of this Carter and switching to a
> Weber? i've seen this mentioned and am curious....
>
> thanks and i'll post and mention whether the choke pull-off replacement
> has any effect...
> bennett
>

 

Before you start tearing down the carb, check the idle tubes. I'm sure Bill
can provide a link. I went through SEVEN carbs on my 87 YJ before I gave up
on the 'professionals' and crawled back under the hood.

"bobvonbob" <bennettvonbennett@gmail.com> wrote in message
news:1143172476.319368.121040@i40g2000cwc.googlegr oups.com...
> thanks bill - i'll try the choke pull-off!
>
> i have a slight problem with a lack of avail. workspace - nowhere to
> soak parts, no compressor to blow out ports, etc - also this sucker is
> soon to be my only vehicle so time is of the essence - all that said:
> d'ya think its better to attempt to rebuild the carb myself or to by a
> rebuilt one from NAPA or wherever..
> .
> also any good links for getting rid of this Carter and switching to a
> Weber? i've seen this mentioned and am curious....
>
> thanks and i'll post and mention whether the choke pull-off replacement
> has any effect...
> bennett
>

 

It has a carb. On the second fast start, you will need to pump the gas
like mad to get it going because the POS (piece of sh..) timer choke has
opened. Once you wait a bit, the choke closes and it starts back up...
The choke opens by how long it has seen 12 volts. It doesn't care how
warm or cold the engine 'really' is.

I have never seen the choke pull off Bill mentioned go bad on a Jeep
carb.... When they do fail you get a 'stable' high idle that can't be
turned down but it won't cause stalling.

I highly recommend a manual choke kit for them. It makes it sooo nice
when trying to drive it before it is fully warmed up... Most auto parts
stores sell the kits. The heavy duty kit comes with the correct choke
replacement parts and is a bolt on unit.

A Carb kit for them is about $20.00 and is easy to do. I recommend you
don't take any parts apart that need adjusting unless you have to to
clean them.

One thing that can aggravate this is having the gas filter in upside
down or having the wrong gas filter in it. The filter has 2 outlets.
The center outlet goes to the carb and the top outlet goes to the return
line. If the return line outlet isn't at the top, then gas can syphon
back to the gas tank or in a shutdown case, get pushed back so it vapor
locks or air locks the gas line. If this happens, you can prime the
carb with a quarter cup of gas down it's throat and the engine will go
vroom. You might have to do it twice to get the pump to pick up the
fuel again. It takes a 'lot' of cranking to overcome this vapor lock
otherwise, a battery killing 'lot'....

Now to address the idle. First off you will need to see if the carb
float bowl and gas tank vent is working. If it is shot, you will have
to replace it or disconnect it and drive with lots of gas fumes around
while waiting for a new one...

To test it have the engine at idle and trace the PCV line to the back of
the carb. There you will find a solenoid thing that can actually be
replaced with a T fitting if it isn't functioning and they do fail.
(when they fail massive amounts of oil will blow into the air filter)

Off this solenoid or T fitting one line will go way down below the brake
booster to a charcoal canister sitting at the bottom of the fender. At
idle pinch this line to the canister closed. If the idle changes, the
canister purge valve has failed and the canister must be replaced. For
temporary set up purposes, you can unplug this line from the canister
and block it with a tight fitting bolt so the PCV system is now sealed
back up.

If this canister is working ok, then I would suspect the carb has the
common problem of plugged up idle circuit tubes. These brass tubes have
crimped ends that are too small so they plug up easy. It is recommended
to physically ream these ends out because the chemical cleans just won't
get them clean. That is why a lot of 'professionally' rebuilt carbs
still have blocked up tubes. It is a 'no no' for a rebuilder to
physically ream parts so they rely on chemicals and put out crappy
rebuilt carbs.

Here is a good site on the idle tube issue:
http://www.off-road.com/jeep/tech/engine/carter.html

The tool used can be found at welding supply stores. The small drills
or files are used for cleaning torch tips. I can actually pull out the
venturi from the top once I remove the choke plate. It will lift up and
spin around and pull out past the choke plate pivot bar. Best to do the
first time as part of a carb kit and clean up.

When doing the carb clean, pay close attention to the chunk of gas line
from the filter to the carb. The U shaped line will hold all kinds of
crud that builds up as the vehicle sits and the gas evaporates away. It
is often a source for a second bout of plugged up idle tubes that seems
to happen just after a carb clean....

If you suspect the brake booster is bad, just unplug it at the booster
and block the line to see if the idle gets right.

Hope some of this helps....

Feel free to ask if any of it isn't clear.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

bennettvonbennett@gmail.com wrote:
>
> can one of you Jeep gurus help me out? i have been given a 1987 Jeep
> Wrangler (4.2L 6cyl) and have been having trouble getting it to start
> reliably.
> when the vehicle is completely cold it starts right up no problem, it
> will idle at approx 1000rpm and - while its still parked - can be
> revved up with plenty of power. however, if i shut it off and then try
> to restart it - no dice. motor turns over and spark is present but the
> engine will not catch, no matter whether the accel pedal is left alone
> or held down. this is true even when the motor has initially run for
> even just a minute or so.
> also when it is driven the idle cannot be allowed to dip below approx
> 1100 rpm or it will stall and not start again for some time (at least
> 30 minutes or so but i havent figured out exactly how much time is
> required yet...). i have very little history on the vehicle, and aside
> from the fact that its had this same problem now for about a year, i
> dont know if this problem appeared suddenly or developed over time...
> i have replaced the rotor, cap, plugs, plug-wires, and in-line fuel
> filter. the air filter while not new appears servicable. i also added
> some stabilizer to the fuel and put a few gallons of new premium in the
> tank...
> could the problem be in any way related to the brake booster? there are
> signs of previous brake fluid leakage around the flange where the
> master cyl bolts on (bubbled paint etc) but i dont see any actual
> leakage now... perhaps this is why can idle and rev while parked but
> cannot idle when driven?
> but then why no restart when its just been sitting at the curb and the
> engine is just a tiny bit 'warm'?
> perhaps a more likely culprit is the choke circut? or the carburator
> generally? the accelerator pump at least is working - strong jet of
> fuel w/accel pedal pressed.
> i dont know how to check the various different parts of the fuel
> delivery system individually so i dont have any idea even where to
> start - if i was to purchase a rebuilt BBD carb would this come with
> all the various solenoids, stepper motors, choke assembly, diaphragms,
> throttle switch. etc etc? probably not i would think... does this
> matter?
> whaddya think? i'm no mechanic but i'm not totally ignorant of
> carburated engines either. can you point me in the right direction so i
> can get my 'new' black beast running?
>
> eagerly awaiting your diagnostic wisdom,
> thanks in advance.
> Bennett

 

It has a carb. On the second fast start, you will need to pump the gas
like mad to get it going because the POS (piece of sh..) timer choke has
opened. Once you wait a bit, the choke closes and it starts back up...
The choke opens by how long it has seen 12 volts. It doesn't care how
warm or cold the engine 'really' is.

I have never seen the choke pull off Bill mentioned go bad on a Jeep
carb.... When they do fail you get a 'stable' high idle that can't be
turned down but it won't cause stalling.

I highly recommend a manual choke kit for them. It makes it sooo nice
when trying to drive it before it is fully warmed up... Most auto parts
stores sell the kits. The heavy duty kit comes with the correct choke
replacement parts and is a bolt on unit.

A Carb kit for them is about $20.00 and is easy to do. I recommend you
don't take any parts apart that need adjusting unless you have to to
clean them.

One thing that can aggravate this is having the gas filter in upside
down or having the wrong gas filter in it. The filter has 2 outlets.
The center outlet goes to the carb and the top outlet goes to the return
line. If the return line outlet isn't at the top, then gas can syphon
back to the gas tank or in a shutdown case, get pushed back so it vapor
locks or air locks the gas line. If this happens, you can prime the
carb with a quarter cup of gas down it's throat and the engine will go
vroom. You might have to do it twice to get the pump to pick up the
fuel again. It takes a 'lot' of cranking to overcome this vapor lock
otherwise, a battery killing 'lot'....

Now to address the idle. First off you will need to see if the carb
float bowl and gas tank vent is working. If it is shot, you will have
to replace it or disconnect it and drive with lots of gas fumes around
while waiting for a new one...

To test it have the engine at idle and trace the PCV line to the back of
the carb. There you will find a solenoid thing that can actually be
replaced with a T fitting if it isn't functioning and they do fail.
(when they fail massive amounts of oil will blow into the air filter)

Off this solenoid or T fitting one line will go way down below the brake
booster to a charcoal canister sitting at the bottom of the fender. At
idle pinch this line to the canister closed. If the idle changes, the
canister purge valve has failed and the canister must be replaced. For
temporary set up purposes, you can unplug this line from the canister
and block it with a tight fitting bolt so the PCV system is now sealed
back up.

If this canister is working ok, then I would suspect the carb has the
common problem of plugged up idle circuit tubes. These brass tubes have
crimped ends that are too small so they plug up easy. It is recommended
to physically ream these ends out because the chemical cleans just won't
get them clean. That is why a lot of 'professionally' rebuilt carbs
still have blocked up tubes. It is a 'no no' for a rebuilder to
physically ream parts so they rely on chemicals and put out crappy
rebuilt carbs.

Here is a good site on the idle tube issue:
http://www.off-road.com/jeep/tech/engine/carter.html

The tool used can be found at welding supply stores. The small drills
or files are used for cleaning torch tips. I can actually pull out the
venturi from the top once I remove the choke plate. It will lift up and
spin around and pull out past the choke plate pivot bar. Best to do the
first time as part of a carb kit and clean up.

When doing the carb clean, pay close attention to the chunk of gas line
from the filter to the carb. The U shaped line will hold all kinds of
crud that builds up as the vehicle sits and the gas evaporates away. It
is often a source for a second bout of plugged up idle tubes that seems
to happen just after a carb clean....

If you suspect the brake booster is bad, just unplug it at the booster
and block the line to see if the idle gets right.

Hope some of this helps....

Feel free to ask if any of it isn't clear.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

bennettvonbennett@gmail.com wrote:
>
> can one of you Jeep gurus help me out? i have been given a 1987 Jeep
> Wrangler (4.2L 6cyl) and have been having trouble getting it to start
> reliably.
> when the vehicle is completely cold it starts right up no problem, it
> will idle at approx 1000rpm and - while its still parked - can be
> revved up with plenty of power. however, if i shut it off and then try
> to restart it - no dice. motor turns over and spark is present but the
> engine will not catch, no matter whether the accel pedal is left alone
> or held down. this is true even when the motor has initially run for
> even just a minute or so.
> also when it is driven the idle cannot be allowed to dip below approx
> 1100 rpm or it will stall and not start again for some time (at least
> 30 minutes or so but i havent figured out exactly how much time is
> required yet...). i have very little history on the vehicle, and aside
> from the fact that its had this same problem now for about a year, i
> dont know if this problem appeared suddenly or developed over time...
> i have replaced the rotor, cap, plugs, plug-wires, and in-line fuel
> filter. the air filter while not new appears servicable. i also added
> some stabilizer to the fuel and put a few gallons of new premium in the
> tank...
> could the problem be in any way related to the brake booster? there are
> signs of previous brake fluid leakage around the flange where the
> master cyl bolts on (bubbled paint etc) but i dont see any actual
> leakage now... perhaps this is why can idle and rev while parked but
> cannot idle when driven?
> but then why no restart when its just been sitting at the curb and the
> engine is just a tiny bit 'warm'?
> perhaps a more likely culprit is the choke circut? or the carburator
> generally? the accelerator pump at least is working - strong jet of
> fuel w/accel pedal pressed.
> i dont know how to check the various different parts of the fuel
> delivery system individually so i dont have any idea even where to
> start - if i was to purchase a rebuilt BBD carb would this come with
> all the various solenoids, stepper motors, choke assembly, diaphragms,
> throttle switch. etc etc? probably not i would think... does this
> matter?
> whaddya think? i'm no mechanic but i'm not totally ignorant of
> carburated engines either. can you point me in the right direction so i
> can get my 'new' black beast running?
>
> eagerly awaiting your diagnostic wisdom,
> thanks in advance.
> Bennett

 

It has a carb. On the second fast start, you will need to pump the gas
like mad to get it going because the POS (piece of sh..) timer choke has
opened. Once you wait a bit, the choke closes and it starts back up...
The choke opens by how long it has seen 12 volts. It doesn't care how
warm or cold the engine 'really' is.

I have never seen the choke pull off Bill mentioned go bad on a Jeep
carb.... When they do fail you get a 'stable' high idle that can't be
turned down but it won't cause stalling.

I highly recommend a manual choke kit for them. It makes it sooo nice
when trying to drive it before it is fully warmed up... Most auto parts
stores sell the kits. The heavy duty kit comes with the correct choke
replacement parts and is a bolt on unit.

A Carb kit for them is about $20.00 and is easy to do. I recommend you
don't take any parts apart that need adjusting unless you have to to
clean them.

One thing that can aggravate this is having the gas filter in upside
down or having the wrong gas filter in it. The filter has 2 outlets.
The center outlet goes to the carb and the top outlet goes to the return
line. If the return line outlet isn't at the top, then gas can syphon
back to the gas tank or in a shutdown case, get pushed back so it vapor
locks or air locks the gas line. If this happens, you can prime the
carb with a quarter cup of gas down it's throat and the engine will go
vroom. You might have to do it twice to get the pump to pick up the
fuel again. It takes a 'lot' of cranking to overcome this vapor lock
otherwise, a battery killing 'lot'....

Now to address the idle. First off you will need to see if the carb
float bowl and gas tank vent is working. If it is shot, you will have
to replace it or disconnect it and drive with lots of gas fumes around
while waiting for a new one...

To test it have the engine at idle and trace the PCV line to the back of
the carb. There you will find a solenoid thing that can actually be
replaced with a T fitting if it isn't functioning and they do fail.
(when they fail massive amounts of oil will blow into the air filter)

Off this solenoid or T fitting one line will go way down below the brake
booster to a charcoal canister sitting at the bottom of the fender. At
idle pinch this line to the canister closed. If the idle changes, the
canister purge valve has failed and the canister must be replaced. For
temporary set up purposes, you can unplug this line from the canister
and block it with a tight fitting bolt so the PCV system is now sealed
back up.

If this canister is working ok, then I would suspect the carb has the
common problem of plugged up idle circuit tubes. These brass tubes have
crimped ends that are too small so they plug up easy. It is recommended
to physically ream these ends out because the chemical cleans just won't
get them clean. That is why a lot of 'professionally' rebuilt carbs
still have blocked up tubes. It is a 'no no' for a rebuilder to
physically ream parts so they rely on chemicals and put out crappy
rebuilt carbs.

Here is a good site on the idle tube issue:
http://www.off-road.com/jeep/tech/engine/carter.html

The tool used can be found at welding supply stores. The small drills
or files are used for cleaning torch tips. I can actually pull out the
venturi from the top once I remove the choke plate. It will lift up and
spin around and pull out past the choke plate pivot bar. Best to do the
first time as part of a carb kit and clean up.

When doing the carb clean, pay close attention to the chunk of gas line
from the filter to the carb. The U shaped line will hold all kinds of
crud that builds up as the vehicle sits and the gas evaporates away. It
is often a source for a second bout of plugged up idle tubes that seems
to happen just after a carb clean....

If you suspect the brake booster is bad, just unplug it at the booster
and block the line to see if the idle gets right.

Hope some of this helps....

Feel free to ask if any of it isn't clear.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

bennettvonbennett@gmail.com wrote:
>
> can one of you Jeep gurus help me out? i have been given a 1987 Jeep
> Wrangler (4.2L 6cyl) and have been having trouble getting it to start
> reliably.
> when the vehicle is completely cold it starts right up no problem, it
> will idle at approx 1000rpm and - while its still parked - can be
> revved up with plenty of power. however, if i shut it off and then try
> to restart it - no dice. motor turns over and spark is present but the
> engine will not catch, no matter whether the accel pedal is left alone
> or held down. this is true even when the motor has initially run for
> even just a minute or so.
> also when it is driven the idle cannot be allowed to dip below approx
> 1100 rpm or it will stall and not start again for some time (at least
> 30 minutes or so but i havent figured out exactly how much time is
> required yet...). i have very little history on the vehicle, and aside
> from the fact that its had this same problem now for about a year, i
> dont know if this problem appeared suddenly or developed over time...
> i have replaced the rotor, cap, plugs, plug-wires, and in-line fuel
> filter. the air filter while not new appears servicable. i also added
> some stabilizer to the fuel and put a few gallons of new premium in the
> tank...
> could the problem be in any way related to the brake booster? there are
> signs of previous brake fluid leakage around the flange where the
> master cyl bolts on (bubbled paint etc) but i dont see any actual
> leakage now... perhaps this is why can idle and rev while parked but
> cannot idle when driven?
> but then why no restart when its just been sitting at the curb and the
> engine is just a tiny bit 'warm'?
> perhaps a more likely culprit is the choke circut? or the carburator
> generally? the accelerator pump at least is working - strong jet of
> fuel w/accel pedal pressed.
> i dont know how to check the various different parts of the fuel
> delivery system individually so i dont have any idea even where to
> start - if i was to purchase a rebuilt BBD carb would this come with
> all the various solenoids, stepper motors, choke assembly, diaphragms,
> throttle switch. etc etc? probably not i would think... does this
> matter?
> whaddya think? i'm no mechanic but i'm not totally ignorant of
> carburated engines either. can you point me in the right direction so i
> can get my 'new' black beast running?
>
> eagerly awaiting your diagnostic wisdom,
> thanks in advance.
> Bennett

 

Sounds like you need to deal with the carb.

First thing I'd do is ream out the idle tubes. this can be done on the
vehicle. Get a "drill style tip cleaner" at your local welding shop. $8
http://www.off-road.com/jeep/tech/engine/carter.html
Don't be afraid to ream these out a bit oversize, there was a factory
tech bulleton out on this.

See if the choke is fully closed to start, opensfully when it is warm.
Fix as required. You can set the pulloff rate (cool to almost warm rate)
later.

Pick up a carb kit based on the number tab on the carb. Inside are
instructions for setting the various levers and choke postions. These
are very specific to individual models. Maybe someone here can scan the
instructions and the spec sheet. Hayes and Chilton manuals only give the
general disassembly instructions, not the specs.

Just rebuild it on your kitchen table. It's been done many times before.
Just drain the gas before you bring it in!

Make sure your vac lines go where they are supposed to:
http://www.off-road.com/jeep/tech/258bbd/index.htm
http://home.sprynet.com/~dale02/vactails.htm

Your carb has a motorized mixture control system run off the computer.
Pretty problematic. New servo is $120 (!!!), odds are good it is not
working correctly. You can look down the carb throat, see the two
needles in the bottom shuttling in and out as you move the gas pedal or
spray a bit of carb cleaner down the throat. Some of the folks have put
the computer to sleep, modify the base of the carb to adjust mixture
with the standard mix screws that are currently hidden.




bennettvonbennett@gmail.com wrote:
> can one of you Jeep gurus help me out? i have been given a 1987 Jeep
> Wrangler (4.2L 6cyl) and have been having trouble getting it to start
> reliably.
> when the vehicle is completely cold it starts right up no problem, it
> will idle at approx 1000rpm and - while its still parked - can be
> revved up with plenty of power. however, if i shut it off and then try
> to restart it - no dice. motor turns over and spark is present but the
> engine will not catch, no matter whether the accel pedal is left alone
> or held down. this is true even when the motor has initially run for
> even just a minute or so.
> also when it is driven the idle cannot be allowed to dip below approx
> 1100 rpm or it will stall and not start again for some time (at least
> 30 minutes or so but i havent figured out exactly how much time is
> required yet...). i have very little history on the vehicle, and aside
> from the fact that its had this same problem now for about a year, i
> dont know if this problem appeared suddenly or developed over time...
> i have replaced the rotor, cap, plugs, plug-wires, and in-line fuel
> filter. the air filter while not new appears servicable. i also added
> some stabilizer to the fuel and put a few gallons of new premium in the
> tank...
> could the problem be in any way related to the brake booster? there are
> signs of previous brake fluid leakage around the flange where the
> master cyl bolts on (bubbled paint etc) but i dont see any actual
> leakage now... perhaps this is why can idle and rev while parked but
> cannot idle when driven?
> but then why no restart when its just been sitting at the curb and the
> engine is just a tiny bit 'warm'?
> perhaps a more likely culprit is the choke circut? or the carburator
> generally? the accelerator pump at least is working - strong jet of
> fuel w/accel pedal pressed.
> i dont know how to check the various different parts of the fuel
> delivery system individually so i dont have any idea even where to
> start - if i was to purchase a rebuilt BBD carb would this come with
> all the various solenoids, stepper motors, choke assembly, diaphragms,
> throttle switch. etc etc? probably not i would think... does this
> matter?
> whaddya think? i'm no mechanic but i'm not totally ignorant of
> carburated engines either. can you point me in the right direction so i
> can get my 'new' black beast running?
>
> eagerly awaiting your diagnostic wisdom,
> thanks in advance.
> Bennett
>

 

Sounds like you need to deal with the carb.

First thing I'd do is ream out the idle tubes. this can be done on the
vehicle. Get a "drill style tip cleaner" at your local welding shop. $8
http://www.off-road.com/jeep/tech/engine/carter.html
Don't be afraid to ream these out a bit oversize, there was a factory
tech bulleton out on this.

See if the choke is fully closed to start, opensfully when it is warm.
Fix as required. You can set the pulloff rate (cool to almost warm rate)
later.

Pick up a carb kit based on the number tab on the carb. Inside are
instructions for setting the various levers and choke postions. These
are very specific to individual models. Maybe someone here can scan the
instructions and the spec sheet. Hayes and Chilton manuals only give the
general disassembly instructions, not the specs.

Just rebuild it on your kitchen table. It's been done many times before.
Just drain the gas before you bring it in!

Make sure your vac lines go where they are supposed to:
http://www.off-road.com/jeep/tech/258bbd/index.htm
http://home.sprynet.com/~dale02/vactails.htm

Your carb has a motorized mixture control system run off the computer.
Pretty problematic. New servo is $120 (!!!), odds are good it is not
working correctly. You can look down the carb throat, see the two
needles in the bottom shuttling in and out as you move the gas pedal or
spray a bit of carb cleaner down the throat. Some of the folks have put
the computer to sleep, modify the base of the carb to adjust mixture
with the standard mix screws that are currently hidden.




bennettvonbennett@gmail.com wrote:
> can one of you Jeep gurus help me out? i have been given a 1987 Jeep
> Wrangler (4.2L 6cyl) and have been having trouble getting it to start
> reliably.
> when the vehicle is completely cold it starts right up no problem, it
> will idle at approx 1000rpm and - while its still parked - can be
> revved up with plenty of power. however, if i shut it off and then try
> to restart it - no dice. motor turns over and spark is present but the
> engine will not catch, no matter whether the accel pedal is left alone
> or held down. this is true even when the motor has initially run for
> even just a minute or so.
> also when it is driven the idle cannot be allowed to dip below approx
> 1100 rpm or it will stall and not start again for some time (at least
> 30 minutes or so but i havent figured out exactly how much time is
> required yet...). i have very little history on the vehicle, and aside
> from the fact that its had this same problem now for about a year, i
> dont know if this problem appeared suddenly or developed over time...
> i have replaced the rotor, cap, plugs, plug-wires, and in-line fuel
> filter. the air filter while not new appears servicable. i also added
> some stabilizer to the fuel and put a few gallons of new premium in the
> tank...
> could the problem be in any way related to the brake booster? there are
> signs of previous brake fluid leakage around the flange where the
> master cyl bolts on (bubbled paint etc) but i dont see any actual
> leakage now... perhaps this is why can idle and rev while parked but
> cannot idle when driven?
> but then why no restart when its just been sitting at the curb and the
> engine is just a tiny bit 'warm'?
> perhaps a more likely culprit is the choke circut? or the carburator
> generally? the accelerator pump at least is working - strong jet of
> fuel w/accel pedal pressed.
> i dont know how to check the various different parts of the fuel
> delivery system individually so i dont have any idea even where to
> start - if i was to purchase a rebuilt BBD carb would this come with
> all the various solenoids, stepper motors, choke assembly, diaphragms,
> throttle switch. etc etc? probably not i would think... does this
> matter?
> whaddya think? i'm no mechanic but i'm not totally ignorant of
> carburated engines either. can you point me in the right direction so i
> can get my 'new' black beast running?
>
> eagerly awaiting your diagnostic wisdom,
> thanks in advance.
> Bennett
>

 

Sounds like you need to deal with the carb.

First thing I'd do is ream out the idle tubes. this can be done on the
vehicle. Get a "drill style tip cleaner" at your local welding shop. $8
http://www.off-road.com/jeep/tech/engine/carter.html
Don't be afraid to ream these out a bit oversize, there was a factory
tech bulleton out on this.

See if the choke is fully closed to start, opensfully when it is warm.
Fix as required. You can set the pulloff rate (cool to almost warm rate)
later.

Pick up a carb kit based on the number tab on the carb. Inside are
instructions for setting the various levers and choke postions. These
are very specific to individual models. Maybe someone here can scan the
instructions and the spec sheet. Hayes and Chilton manuals only give the
general disassembly instructions, not the specs.

Just rebuild it on your kitchen table. It's been done many times before.
Just drain the gas before you bring it in!

Make sure your vac lines go where they are supposed to:
http://www.off-road.com/jeep/tech/258bbd/index.htm
http://home.sprynet.com/~dale02/vactails.htm

Your carb has a motorized mixture control system run off the computer.
Pretty problematic. New servo is $120 (!!!), odds are good it is not
working correctly. You can look down the carb throat, see the two
needles in the bottom shuttling in and out as you move the gas pedal or
spray a bit of carb cleaner down the throat. Some of the folks have put
the computer to sleep, modify the base of the carb to adjust mixture
with the standard mix screws that are currently hidden.




bennettvonbennett@gmail.com wrote:
> can one of you Jeep gurus help me out? i have been given a 1987 Jeep
> Wrangler (4.2L 6cyl) and have been having trouble getting it to start
> reliably.
> when the vehicle is completely cold it starts right up no problem, it
> will idle at approx 1000rpm and - while its still parked - can be
> revved up with plenty of power. however, if i shut it off and then try
> to restart it - no dice. motor turns over and spark is present but the
> engine will not catch, no matter whether the accel pedal is left alone
> or held down. this is true even when the motor has initially run for
> even just a minute or so.
> also when it is driven the idle cannot be allowed to dip below approx
> 1100 rpm or it will stall and not start again for some time (at least
> 30 minutes or so but i havent figured out exactly how much time is
> required yet...). i have very little history on the vehicle, and aside
> from the fact that its had this same problem now for about a year, i
> dont know if this problem appeared suddenly or developed over time...
> i have replaced the rotor, cap, plugs, plug-wires, and in-line fuel
> filter. the air filter while not new appears servicable. i also added
> some stabilizer to the fuel and put a few gallons of new premium in the
> tank...
> could the problem be in any way related to the brake booster? there are
> signs of previous brake fluid leakage around the flange where the
> master cyl bolts on (bubbled paint etc) but i dont see any actual
> leakage now... perhaps this is why can idle and rev while parked but
> cannot idle when driven?
> but then why no restart when its just been sitting at the curb and the
> engine is just a tiny bit 'warm'?
> perhaps a more likely culprit is the choke circut? or the carburator
> generally? the accelerator pump at least is working - strong jet of
> fuel w/accel pedal pressed.
> i dont know how to check the various different parts of the fuel
> delivery system individually so i dont have any idea even where to
> start - if i was to purchase a rebuilt BBD carb would this come with
> all the various solenoids, stepper motors, choke assembly, diaphragms,
> throttle switch. etc etc? probably not i would think... does this
> matter?
> whaddya think? i'm no mechanic but i'm not totally ignorant of
> carburated engines either. can you point me in the right direction so i
> can get my 'new' black beast running?
>
> eagerly awaiting your diagnostic wisdom,
> thanks in advance.
> Bennett
>

 

thanks Mike - i will attend to the idle tubes today or tomorrow and let
you know what happens - i appreciate all the free advice - i'd like to
start drivin this thing thru the, soon to be, springtime mud!
cheers,
bennett