YJ runs rough on startup?
 

Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
Weber K551 for my newly rebuilt Carter. It starts great and, after it
warms up, runs great, but when I start it cold, it runs at fast idle
for 2-3 seconds, then drops to about 600, running very, *very* rough
for about a minute. Situation stays the same if I rev it higher.
Then it goes back to fast idle and runs fine from there. Sounds like
detonation, or like it's only firing on two cylinders - a neighbor
heard it and thought I was revving a Harley V-twin. Can't figure it
out. Almost positive I have all my vacuum hoses connected right, and
I replaced my O2 sensor at the same time as the carb. Installed new
spark plugs today, (the cap, rotor, and wires only have a few thousand
miles on them) new air filter, I can't figure out what the problem
is. Any suggestions as to the cause of the trouble? Thanks all.
-Micah

Re: YJ runs rough on startup?
 

Micah wrote:
> Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
> Weber K551 for my newly rebuilt Carter. It starts great and, after it
> warms up, runs great, but when I start it cold, it runs at fast idle
> for 2-3 seconds, then drops to about 600, running very, *very* rough
> for about a minute. Situation stays the same if I rev it higher.
> Then it goes back to fast idle and runs fine from there. Sounds like
> detonation, or like it's only firing on two cylinders - a neighbor
> heard it and thought I was revving a Harley V-twin. Can't figure it
> out. Almost positive I have all my vacuum hoses connected right, and
> I replaced my O2 sensor at the same time as the carb. Installed new
> spark plugs today, (the cap, rotor, and wires only have a few thousand
> miles on them) new air filter, I can't figure out what the problem
> is. Any suggestions as to the cause of the trouble? Thanks all.
> -Micah

From foggy memory.

Check the choke pullback. Should be a small wire connecor
on the choke which you bend to increase the pull-back. The
setting should be about .140 inches. Bend the choke connector
wire until you get enough clearance. You can check by attaching
a hose to the choke and sucking on it or using a vac pump.

--
DougW

Re: YJ runs rough on startup?
 

Micah wrote:
> Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
> Weber K551 for my newly rebuilt Carter. It starts great and, after it
> warms up, runs great, but when I start it cold, it runs at fast idle
> for 2-3 seconds, then drops to about 600, running very, *very* rough
> for about a minute. Situation stays the same if I rev it higher.
> Then it goes back to fast idle and runs fine from there. Sounds like
> detonation, or like it's only firing on two cylinders - a neighbor
> heard it and thought I was revving a Harley V-twin. Can't figure it
> out. Almost positive I have all my vacuum hoses connected right, and
> I replaced my O2 sensor at the same time as the carb. Installed new
> spark plugs today, (the cap, rotor, and wires only have a few thousand
> miles on them) new air filter, I can't figure out what the problem
> is. Any suggestions as to the cause of the trouble? Thanks all.
> -Micah

From foggy memory.

Check the choke pullback. Should be a small wire connecor
on the choke which you bend to increase the pull-back. The
setting should be about .140 inches. Bend the choke connector
wire until you get enough clearance. You can check by attaching
a hose to the choke and sucking on it or using a vac pump.

--
DougW

Re: YJ runs rough on startup?
 

Micah wrote:
> Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
> Weber K551 for my newly rebuilt Carter. It starts great and, after it
> warms up, runs great, but when I start it cold, it runs at fast idle
> for 2-3 seconds, then drops to about 600, running very, *very* rough
> for about a minute. Situation stays the same if I rev it higher.
> Then it goes back to fast idle and runs fine from there. Sounds like
> detonation, or like it's only firing on two cylinders - a neighbor
> heard it and thought I was revving a Harley V-twin. Can't figure it
> out. Almost positive I have all my vacuum hoses connected right, and
> I replaced my O2 sensor at the same time as the carb. Installed new
> spark plugs today, (the cap, rotor, and wires only have a few thousand
> miles on them) new air filter, I can't figure out what the problem
> is. Any suggestions as to the cause of the trouble? Thanks all.
> -Micah

From foggy memory.

Check the choke pullback. Should be a small wire connecor
on the choke which you bend to increase the pull-back. The
setting should be about .140 inches. Bend the choke connector
wire until you get enough clearance. You can check by attaching
a hose to the choke and sucking on it or using a vac pump.

--
DougW

Re: YJ runs rough on startup?
 

Good idea. I'll check it and let you know.

Thanks.

Re: YJ runs rough on startup?
 

Good idea. I'll check it and let you know.

Thanks.

Re: YJ runs rough on startup?
 

Good idea. I'll check it and let you know.

Thanks.

Re: YJ runs rough on startup?
 

Micah wrote:
> Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
> Weber K551 for my newly rebuilt Carter. It starts great and, after it
> warms up, runs great, but when I start it cold, it runs at fast idle
> for 2-3 seconds, then drops to about 600, running very, *very* rough
> for about a minute. Situation stays the same if I rev it higher.
> Then it goes back to fast idle and runs fine from there. Sounds like
> detonation, or like it's only firing on two cylinders - a neighbor
> heard it and thought I was revving a Harley V-twin. Can't figure it
> out. Almost positive I have all my vacuum hoses connected right, and
> I replaced my O2 sensor at the same time as the carb. Installed new
> spark plugs today, (the cap, rotor, and wires only have a few thousand
> miles on them) new air filter, I can't figure out what the problem
> is. Any suggestions as to the cause of the trouble? Thanks all.
> -Micah
>

Well... when mine does that I usually am in need of a new distributor
cap and rotor and it is usually on a damp day.

I think it is condensation inside the distributor cap affecting dirty
parts.

You might want to give the insides of the cap a spray clean with WD40,
that does it wonders sometimes by cleaning out the carbon bits.

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)

Re: YJ runs rough on startup?
 

Micah wrote:
> Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
> Weber K551 for my newly rebuilt Carter. It starts great and, after it
> warms up, runs great, but when I start it cold, it runs at fast idle
> for 2-3 seconds, then drops to about 600, running very, *very* rough
> for about a minute. Situation stays the same if I rev it higher.
> Then it goes back to fast idle and runs fine from there. Sounds like
> detonation, or like it's only firing on two cylinders - a neighbor
> heard it and thought I was revving a Harley V-twin. Can't figure it
> out. Almost positive I have all my vacuum hoses connected right, and
> I replaced my O2 sensor at the same time as the carb. Installed new
> spark plugs today, (the cap, rotor, and wires only have a few thousand
> miles on them) new air filter, I can't figure out what the problem
> is. Any suggestions as to the cause of the trouble? Thanks all.
> -Micah
>

Well... when mine does that I usually am in need of a new distributor
cap and rotor and it is usually on a damp day.

I think it is condensation inside the distributor cap affecting dirty
parts.

You might want to give the insides of the cap a spray clean with WD40,
that does it wonders sometimes by cleaning out the carbon bits.

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)

Re: YJ runs rough on startup?
 

Micah wrote:
> Hello everyone. 258, Manual, 1988. Last weekend I swapped out my
> Weber K551 for my newly rebuilt Carter. It starts great and, after it
> warms up, runs great, but when I start it cold, it runs at fast idle
> for 2-3 seconds, then drops to about 600, running very, *very* rough
> for about a minute. Situation stays the same if I rev it higher.
> Then it goes back to fast idle and runs fine from there. Sounds like
> detonation, or like it's only firing on two cylinders - a neighbor
> heard it and thought I was revving a Harley V-twin. Can't figure it
> out. Almost positive I have all my vacuum hoses connected right, and
> I replaced my O2 sensor at the same time as the carb. Installed new
> spark plugs today, (the cap, rotor, and wires only have a few thousand
> miles on them) new air filter, I can't figure out what the problem
> is. Any suggestions as to the cause of the trouble? Thanks all.
> -Micah
>

Well... when mine does that I usually am in need of a new distributor
cap and rotor and it is usually on a damp day.

I think it is condensation inside the distributor cap affecting dirty
parts.

You might want to give the insides of the cap a spray clean with WD40,
that does it wonders sometimes by cleaning out the carbon bits.

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)