I am going nuts with this problem,

my 91 yj has not started in about six months now!

I changed the oil around october and parked it for a week, then went
to start it up and it cranked and cranked, but didnt start.

Now the list starts...

fuel filter? changed it no help

fuel pump? got a fuel pressure gauge and the fuel rail has pressure
within spec (36-40 psi)

spark? put a timing light on it, i have spark on all 4 plugs

not enough spark?
changed plugs, wires, cap, rotor, coil

injectors not opening?
bought a set of noid lights and they blink like a christmas tree like
they are supposed to, and the plugs are wet, pulled injectors and
replaced o-rings and cleaned as best i could by hand, I couldnt find a
place that would test them to see if they were stuck open

out of time?
put the light on it and cranked it over... looked to be 4 degrees
retarded... changed timing chain(which was a bit slack when i took the
cover off), sprockets and tensioner and noticed the water pump was
leaking, changed that too, now its fireing at 0

electrical?
checked ground strap from block to firewall for continuity - very low
to no resistance, same with negative post of battery to block or
chassis
fuses - all look good, under hood and under dash

bad gas?
siphoned out tank and refilled, cranked a bunch with the release of
the fuel pressure gauge open to get the gas in the lines 'clean'

i am stumped, i guess im back to electrical, i just pulled all of the
underdash fuses except the ignition fuse, it cranks and sounds like
maybe one cylinder is fireing(same as with them all in), my next todos
are to get a code reader and see if i get anything on that, then also
check the ground to the coil, then maybe replace the computer...

does anyone know where the computer is located on a '91 yj 2.5l?
can they test that out of the vehicle?

i cant seem to find a timing setting on it, is it supposed to fire
advanced at all? or is that controlled by the computer?

also all the dash gauges/idiot lights are now not coming on (yes with
the fuses in, no check engine light earlier in the disaster which is
why i didnt hook up an OBD reader earlier)

compression? (i would have thought id get more warning on this? it is
a 2.5l turning 31s so it was never peppy)

any other ideas?

sorry if this post sounds a bit angry but im just frustrated, thanks
for any help in advance

Thanks,
Mike

96xj (luckily this one is hauling me around trustilly)
91yj (lets pull it out of its early grave!)
97 ducati monster 900 (new toy :-) )

 

The first thing you should do is buy a code reader like you said. If
the computer isn't bad, it will usually tell you what sensor is bad or
if there is another problem. I had a similiar problem as you, and it
turned out to be the CPS sensor. The only way I was able to determine
this was with a code reader. But that isn't your problem because you
are getting spark. Buy the code reader before you spend any more
money..

-Brent Bogrees
'89 YJ 4.0L w/ 33" BFG MT's
'94 XJ 4.0L w/ 31" BFG AT's
http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html


mcapsu@yahoo.com (mike) wrote in message news:<fed0233a.0404052134.6838cdcf@posting.google. com>...
> I am going nuts with this problem,
>
> my 91 yj has not started in about six months now!
>
> I changed the oil around october and parked it for a week, then went
> to start it up and it cranked and cranked, but didnt start.
>
> Now the list starts...
>
> fuel filter? changed it no help
>
> fuel pump? got a fuel pressure gauge and the fuel rail has pressure
> within spec (36-40 psi)
>
> spark? put a timing light on it, i have spark on all 4 plugs
>
> not enough spark?
> changed plugs, wires, cap, rotor, coil
>
> injectors not opening?
> bought a set of noid lights and they blink like a christmas tree like
> they are supposed to, and the plugs are wet, pulled injectors and
> replaced o-rings and cleaned as best i could by hand, I couldnt find a
> place that would test them to see if they were stuck open
>
> out of time?
> put the light on it and cranked it over... looked to be 4 degrees
> retarded... changed timing chain(which was a bit slack when i took the
> cover off), sprockets and tensioner and noticed the water pump was
> leaking, changed that too, now its fireing at 0
>
> electrical?
> checked ground strap from block to firewall for continuity - very low
> to no resistance, same with negative post of battery to block or
> chassis
> fuses - all look good, under hood and under dash
>
> bad gas?
> siphoned out tank and refilled, cranked a bunch with the release of
> the fuel pressure gauge open to get the gas in the lines 'clean'
>
> i am stumped, i guess im back to electrical, i just pulled all of the
> underdash fuses except the ignition fuse, it cranks and sounds like
> maybe one cylinder is fireing(same as with them all in), my next todos
> are to get a code reader and see if i get anything on that, then also
> check the ground to the coil, then maybe replace the computer...
>
> does anyone know where the computer is located on a '91 yj 2.5l?
> can they test that out of the vehicle?
>
> i cant seem to find a timing setting on it, is it supposed to fire
> advanced at all? or is that controlled by the computer?
>
> also all the dash gauges/idiot lights are now not coming on (yes with
> the fuses in, no check engine light earlier in the disaster which is
> why i didnt hook up an OBD reader earlier)
>
> compression? (i would have thought id get more warning on this? it is
> a 2.5l turning 31s so it was never peppy)
>
> any other ideas?
>
> sorry if this post sounds a bit angry but im just frustrated, thanks
> for any help in advance
>
> Thanks,
> Mike
>
> 96xj (luckily this one is hauling me around trustilly)
> 91yj (lets pull it out of its early grave!)
> 97 ducati monster 900 (new toy :-) )

 

The first thing you should do is buy a code reader like you said. If
the computer isn't bad, it will usually tell you what sensor is bad or
if there is another problem. I had a similiar problem as you, and it
turned out to be the CPS sensor. The only way I was able to determine
this was with a code reader. But that isn't your problem because you
are getting spark. Buy the code reader before you spend any more
money..

-Brent Bogrees
'89 YJ 4.0L w/ 33" BFG MT's
'94 XJ 4.0L w/ 31" BFG AT's
http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html


mcapsu@yahoo.com (mike) wrote in message news:<fed0233a.0404052134.6838cdcf@posting.google. com>...
> I am going nuts with this problem,
>
> my 91 yj has not started in about six months now!
>
> I changed the oil around october and parked it for a week, then went
> to start it up and it cranked and cranked, but didnt start.
>
> Now the list starts...
>
> fuel filter? changed it no help
>
> fuel pump? got a fuel pressure gauge and the fuel rail has pressure
> within spec (36-40 psi)
>
> spark? put a timing light on it, i have spark on all 4 plugs
>
> not enough spark?
> changed plugs, wires, cap, rotor, coil
>
> injectors not opening?
> bought a set of noid lights and they blink like a christmas tree like
> they are supposed to, and the plugs are wet, pulled injectors and
> replaced o-rings and cleaned as best i could by hand, I couldnt find a
> place that would test them to see if they were stuck open
>
> out of time?
> put the light on it and cranked it over... looked to be 4 degrees
> retarded... changed timing chain(which was a bit slack when i took the
> cover off), sprockets and tensioner and noticed the water pump was
> leaking, changed that too, now its fireing at 0
>
> electrical?
> checked ground strap from block to firewall for continuity - very low
> to no resistance, same with negative post of battery to block or
> chassis
> fuses - all look good, under hood and under dash
>
> bad gas?
> siphoned out tank and refilled, cranked a bunch with the release of
> the fuel pressure gauge open to get the gas in the lines 'clean'
>
> i am stumped, i guess im back to electrical, i just pulled all of the
> underdash fuses except the ignition fuse, it cranks and sounds like
> maybe one cylinder is fireing(same as with them all in), my next todos
> are to get a code reader and see if i get anything on that, then also
> check the ground to the coil, then maybe replace the computer...
>
> does anyone know where the computer is located on a '91 yj 2.5l?
> can they test that out of the vehicle?
>
> i cant seem to find a timing setting on it, is it supposed to fire
> advanced at all? or is that controlled by the computer?
>
> also all the dash gauges/idiot lights are now not coming on (yes with
> the fuses in, no check engine light earlier in the disaster which is
> why i didnt hook up an OBD reader earlier)
>
> compression? (i would have thought id get more warning on this? it is
> a 2.5l turning 31s so it was never peppy)
>
> any other ideas?
>
> sorry if this post sounds a bit angry but im just frustrated, thanks
> for any help in advance
>
> Thanks,
> Mike
>
> 96xj (luckily this one is hauling me around trustilly)
> 91yj (lets pull it out of its early grave!)
> 97 ducati monster 900 (new toy :-) )

 

The first thing you should do is buy a code reader like you said. If
the computer isn't bad, it will usually tell you what sensor is bad or
if there is another problem. I had a similiar problem as you, and it
turned out to be the CPS sensor. The only way I was able to determine
this was with a code reader. But that isn't your problem because you
are getting spark. Buy the code reader before you spend any more
money..

-Brent Bogrees
'89 YJ 4.0L w/ 33" BFG MT's
'94 XJ 4.0L w/ 31" BFG AT's
http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html


mcapsu@yahoo.com (mike) wrote in message news:<fed0233a.0404052134.6838cdcf@posting.google. com>...
> I am going nuts with this problem,
>
> my 91 yj has not started in about six months now!
>
> I changed the oil around october and parked it for a week, then went
> to start it up and it cranked and cranked, but didnt start.
>
> Now the list starts...
>
> fuel filter? changed it no help
>
> fuel pump? got a fuel pressure gauge and the fuel rail has pressure
> within spec (36-40 psi)
>
> spark? put a timing light on it, i have spark on all 4 plugs
>
> not enough spark?
> changed plugs, wires, cap, rotor, coil
>
> injectors not opening?
> bought a set of noid lights and they blink like a christmas tree like
> they are supposed to, and the plugs are wet, pulled injectors and
> replaced o-rings and cleaned as best i could by hand, I couldnt find a
> place that would test them to see if they were stuck open
>
> out of time?
> put the light on it and cranked it over... looked to be 4 degrees
> retarded... changed timing chain(which was a bit slack when i took the
> cover off), sprockets and tensioner and noticed the water pump was
> leaking, changed that too, now its fireing at 0
>
> electrical?
> checked ground strap from block to firewall for continuity - very low
> to no resistance, same with negative post of battery to block or
> chassis
> fuses - all look good, under hood and under dash
>
> bad gas?
> siphoned out tank and refilled, cranked a bunch with the release of
> the fuel pressure gauge open to get the gas in the lines 'clean'
>
> i am stumped, i guess im back to electrical, i just pulled all of the
> underdash fuses except the ignition fuse, it cranks and sounds like
> maybe one cylinder is fireing(same as with them all in), my next todos
> are to get a code reader and see if i get anything on that, then also
> check the ground to the coil, then maybe replace the computer...
>
> does anyone know where the computer is located on a '91 yj 2.5l?
> can they test that out of the vehicle?
>
> i cant seem to find a timing setting on it, is it supposed to fire
> advanced at all? or is that controlled by the computer?
>
> also all the dash gauges/idiot lights are now not coming on (yes with
> the fuses in, no check engine light earlier in the disaster which is
> why i didnt hook up an OBD reader earlier)
>
> compression? (i would have thought id get more warning on this? it is
> a 2.5l turning 31s so it was never peppy)
>
> any other ideas?
>
> sorry if this post sounds a bit angry but im just frustrated, thanks
> for any help in advance
>
> Thanks,
> Mike
>
> 96xj (luckily this one is hauling me around trustilly)
> 91yj (lets pull it out of its early grave!)
> 97 ducati monster 900 (new toy :-) )

 

The first thing you should do is buy a code reader like you said. If
the computer isn't bad, it will usually tell you what sensor is bad or
if there is another problem. I had a similiar problem as you, and it
turned out to be the CPS sensor. The only way I was able to determine
this was with a code reader. But that isn't your problem because you
are getting spark. Buy the code reader before you spend any more
money..

-Brent Bogrees
'89 YJ 4.0L w/ 33" BFG MT's
'94 XJ 4.0L w/ 31" BFG AT's
http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html


mcapsu@yahoo.com (mike) wrote in message news:<fed0233a.0404052134.6838cdcf@posting.google. com>...
> I am going nuts with this problem,
>
> my 91 yj has not started in about six months now!
>
> I changed the oil around october and parked it for a week, then went
> to start it up and it cranked and cranked, but didnt start.
>
> Now the list starts...
>
> fuel filter? changed it no help
>
> fuel pump? got a fuel pressure gauge and the fuel rail has pressure
> within spec (36-40 psi)
>
> spark? put a timing light on it, i have spark on all 4 plugs
>
> not enough spark?
> changed plugs, wires, cap, rotor, coil
>
> injectors not opening?
> bought a set of noid lights and they blink like a christmas tree like
> they are supposed to, and the plugs are wet, pulled injectors and
> replaced o-rings and cleaned as best i could by hand, I couldnt find a
> place that would test them to see if they were stuck open
>
> out of time?
> put the light on it and cranked it over... looked to be 4 degrees
> retarded... changed timing chain(which was a bit slack when i took the
> cover off), sprockets and tensioner and noticed the water pump was
> leaking, changed that too, now its fireing at 0
>
> electrical?
> checked ground strap from block to firewall for continuity - very low
> to no resistance, same with negative post of battery to block or
> chassis
> fuses - all look good, under hood and under dash
>
> bad gas?
> siphoned out tank and refilled, cranked a bunch with the release of
> the fuel pressure gauge open to get the gas in the lines 'clean'
>
> i am stumped, i guess im back to electrical, i just pulled all of the
> underdash fuses except the ignition fuse, it cranks and sounds like
> maybe one cylinder is fireing(same as with them all in), my next todos
> are to get a code reader and see if i get anything on that, then also
> check the ground to the coil, then maybe replace the computer...
>
> does anyone know where the computer is located on a '91 yj 2.5l?
> can they test that out of the vehicle?
>
> i cant seem to find a timing setting on it, is it supposed to fire
> advanced at all? or is that controlled by the computer?
>
> also all the dash gauges/idiot lights are now not coming on (yes with
> the fuses in, no check engine light earlier in the disaster which is
> why i didnt hook up an OBD reader earlier)
>
> compression? (i would have thought id get more warning on this? it is
> a 2.5l turning 31s so it was never peppy)
>
> any other ideas?
>
> sorry if this post sounds a bit angry but im just frustrated, thanks
> for any help in advance
>
> Thanks,
> Mike
>
> 96xj (luckily this one is hauling me around trustilly)
> 91yj (lets pull it out of its early grave!)
> 97 ducati monster 900 (new toy :-) )

 

You said there's a spark, but what you measured was that there's enought
pulse in the plug wire to trigger your strobe gun, right? I had a bad
coil once (full of water, actually). The pulse was strong enough to
trigger my strobe, but not enough to create the spark at the plus that I
needed. Unscrew some plugs, lay them to ground and observe the spark.
Just a thought... Good luck!

-Kris
http://eternalbank.com/jeeps.htm


bogrees.1@osu.edu (Brent Bogrees) wrote in
news:6a04cef7.0404060526.2681e272@posting.google.c om:

> The first thing you should do is buy a code reader like you said. If
> the computer isn't bad, it will usually tell you what sensor is bad or
> if there is another problem. I had a similiar problem as you, and it
> turned out to be the CPS sensor. The only way I was able to determine
> this was with a code reader. But that isn't your problem because you
> are getting spark. Buy the code reader before you spend any more
> money..
>
> -Brent Bogrees
> '89 YJ 4.0L w/ 33" BFG MT's
> '94 XJ 4.0L w/ 31" BFG AT's
> http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html
>

>> chassis
>> fuses - all look good, under hood and under dash
>>
>> bad gas?
>> siphoned out tank and refilled, cranked a bunch with the release of
>> the fuel pressure gauge open to get the gas in the lines 'clean'
>>
>> i am stumped, i guess im back to electrical, i just pulled all of the
>

 

You said there's a spark, but what you measured was that there's enought
pulse in the plug wire to trigger your strobe gun, right? I had a bad
coil once (full of water, actually). The pulse was strong enough to
trigger my strobe, but not enough to create the spark at the plus that I
needed. Unscrew some plugs, lay them to ground and observe the spark.
Just a thought... Good luck!

-Kris
http://eternalbank.com/jeeps.htm


bogrees.1@osu.edu (Brent Bogrees) wrote in
news:6a04cef7.0404060526.2681e272@posting.google.c om:

> The first thing you should do is buy a code reader like you said. If
> the computer isn't bad, it will usually tell you what sensor is bad or
> if there is another problem. I had a similiar problem as you, and it
> turned out to be the CPS sensor. The only way I was able to determine
> this was with a code reader. But that isn't your problem because you
> are getting spark. Buy the code reader before you spend any more
> money..
>
> -Brent Bogrees
> '89 YJ 4.0L w/ 33" BFG MT's
> '94 XJ 4.0L w/ 31" BFG AT's
> http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html
>

>> chassis
>> fuses - all look good, under hood and under dash
>>
>> bad gas?
>> siphoned out tank and refilled, cranked a bunch with the release of
>> the fuel pressure gauge open to get the gas in the lines 'clean'
>>
>> i am stumped, i guess im back to electrical, i just pulled all of the
>

 

You said there's a spark, but what you measured was that there's enought
pulse in the plug wire to trigger your strobe gun, right? I had a bad
coil once (full of water, actually). The pulse was strong enough to
trigger my strobe, but not enough to create the spark at the plus that I
needed. Unscrew some plugs, lay them to ground and observe the spark.
Just a thought... Good luck!

-Kris
http://eternalbank.com/jeeps.htm


bogrees.1@osu.edu (Brent Bogrees) wrote in
news:6a04cef7.0404060526.2681e272@posting.google.c om:

> The first thing you should do is buy a code reader like you said. If
> the computer isn't bad, it will usually tell you what sensor is bad or
> if there is another problem. I had a similiar problem as you, and it
> turned out to be the CPS sensor. The only way I was able to determine
> this was with a code reader. But that isn't your problem because you
> are getting spark. Buy the code reader before you spend any more
> money..
>
> -Brent Bogrees
> '89 YJ 4.0L w/ 33" BFG MT's
> '94 XJ 4.0L w/ 31" BFG AT's
> http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html
>

>> chassis
>> fuses - all look good, under hood and under dash
>>
>> bad gas?
>> siphoned out tank and refilled, cranked a bunch with the release of
>> the fuel pressure gauge open to get the gas in the lines 'clean'
>>
>> i am stumped, i guess im back to electrical, i just pulled all of the
>

 

You said there's a spark, but what you measured was that there's enought
pulse in the plug wire to trigger your strobe gun, right? I had a bad
coil once (full of water, actually). The pulse was strong enough to
trigger my strobe, but not enough to create the spark at the plus that I
needed. Unscrew some plugs, lay them to ground and observe the spark.
Just a thought... Good luck!

-Kris
http://eternalbank.com/jeeps.htm


bogrees.1@osu.edu (Brent Bogrees) wrote in
news:6a04cef7.0404060526.2681e272@posting.google.c om:

> The first thing you should do is buy a code reader like you said. If
> the computer isn't bad, it will usually tell you what sensor is bad or
> if there is another problem. I had a similiar problem as you, and it
> turned out to be the CPS sensor. The only way I was able to determine
> this was with a code reader. But that isn't your problem because you
> are getting spark. Buy the code reader before you spend any more
> money..
>
> -Brent Bogrees
> '89 YJ 4.0L w/ 33" BFG MT's
> '94 XJ 4.0L w/ 31" BFG AT's
> http://www.chrr.ohio-state.edu/~bogrees/html/Jeep.html
>

>> chassis
>> fuses - all look good, under hood and under dash
>>
>> bad gas?
>> siphoned out tank and refilled, cranked a bunch with the release of
>> the fuel pressure gauge open to get the gas in the lines 'clean'
>>
>> i am stumped, i guess im back to electrical, i just pulled all of the
>

 

"Brent Bogrees" <bogrees.1@osu.edu> wrote in message
news:6a04cef7.0404060526.2681e272@posting.google.c om...
> The first thing you should do is buy a code reader like you said. If
> the computer isn't bad, it will usually tell you what sensor is bad or
> if there is another problem. I had a similiar problem as you, and it
> turned out to be the CPS sensor. The only way I was able to determine
> this was with a code reader. But that isn't your problem because you
> are getting spark. Buy the code reader before you spend any more
> money..

You don't need a code reader on a '91. Turn the ignition on and off three
times in rapid succession and the codes will blink out with a pause between
each digit. the last code, indicating end of codes is 5-5.
http://www.sierrajeep.com/trouble.htm

Jeff Lowe
'91 YJ
'00 XJ