92 No Start

[GordoSmasho]

I poseted this in the oem section but havent had a whole lot of help there.

So im reaching out to the better dignostic folks out there. I picked up this 92 2dr 4.0 auto 4wd from a fellow member. It has only 146k on it. It has been worked over and tinkered with quite a bit. Looks like it has been in a front end collision at one point. Ive done all I know to do.


It cranks just fine but will not start. Just stumbles while cranking. As soon as you let go of the key it stops.

-Has spark on all cylinders
-Compression is very good 140-150 across
-Exhaust flowes freely
-Verified fuel pressure new pump and filter 40psi while cranking
-Verified the indexing of the distributor
-Tested both the crank position sensor and the cam position sensor, both good
-New plugs wires and rotor
-Was getting a code for the temp sensor so i swapped in a new one and the code is now gone
-The injectors are firing. Verified with node light and fuel pressure drop while cranking with the pump relay pulled
-Ballast resistor is bypassed
-No more codes are present

Still just a stumble while cranking. I can smell fuel out the tailpipe after cranking for a little bit.

What should i look for/test next? Im not one to just start buying new parts with out making sure the old ones dont work. Any idea what sensors are being used at startup? Thanks guys

It was mentioned in the oem section that my ecu may be fried. Though i find that hard to believe when so many functions are working. I could be wrong though. Anyone have a 92 auto ecu i could borrow?

 

[blondejoncherokee]

I dont trust CPS tests, maybe swap it anyway ?

Have you verified that something crazy like the timing chain did not snap ?

chasing wiring around with a multi meter - Checking grounds and voltage at sensors.

Spray some starting fluid in the intake ?

bad coil ? intermittently working?

bad igniter ? intermittently working ?


Ill check through my spare ECUs and see what I have ?

you are 100% on the dizzy being indexed

 

[sneakyjap96]

If the distributor has been pulled possible it's 180 out which will do just that

 

[GordoSmasho]

I dont trust CPS tests, maybe swap it anyway

---I found one new test for the cps i need to do. Im pretty sure i wouldnt be seeing spark if it was bad but again im not as familiar with pre 97s. I may just grab a new one and throw it in there.


Have you verified that something crazy like the timing chain did not snap ?

---i dont think anything crazy like that is happening. That would throw off compression test and it was 140-150 across all cylinders


chasing wiring around with a multi meter - Checking grounds and voltage at sensors.

---I reconstructed a few of the major ground points and got all the grounds solid under the hood. Tested resistance from all points to the battery negative. Very little if any measurable resistance at the few sensors i tested. Made sure the ones i tested had proper voltage from ecm as well.


Spray some starting fluid in the intake ?

---need to pickup some starting fluid. I did try some carb cleaner while cranking. No effect.

bad coil ? intermittently working?

---ill have to check that out

bad igniter ? intermittently working ?

---not sure what an igniter is. Please essplaine.


Ill check through my spare ECUs and see what I have ?

you are 100% on the dizzy being indexed

---i did it three times. Once back one tooth and once forward one tooth and again to put it back to stock according to the fsm install technic. I checked for tdc on compression every time per the fsm install.

When i pulled the spark plugs they were very black although new. I cleaned them up as best i could. I may grab a new set as well and throw them in.

 

[blondejoncherokee]

If the distributor has been pulled possible it's 180 out which will do just that

super good point.

igniter is only for older jeeps I think, renix. never mind. the renix had one under the coil. I don't think the 1992 does ?

remind me to check for a spare ECU, I might have couple.

 

[GordoSmasho]

I dont think the dist had been pulled. Nothing indicated that to me. I was just being thorough. Again i dropped it is per the fsm and it lined up perfectly with the #1 plug wire terminal on the dist. Then i did it so it was one tooth behind and again one tooth ahead. No difference either of the three times.

 

[blondejoncherokee]

I have a snap on MT2500 scanner. not sure if it would help if it aint running

 

[GordoSmasho]

Can you actually scan obd1s. I didnt know there was a port for it.

 

[blondejoncherokee]

Can you actually scan obd1s. I didnt know there was a port for it.

oh maybe not.

I can scan renix I know that .

 

[blondejoncherokee]

http://buy1.snapon.com/products/dia...ticVCS(EAZ0025B01CRevB)/12 JeepOperations.pdf

supposedly the CHR1 adapter does it with the brick. Ill see if I have that adapter

 

[GordoSmasho]

I have a noce high end innova scanner but it only has the obd2 connector for 97+ i think. Didnt see a scan port on it.

 

[GordoSmasho]

The scanner i have doesnt do obd1. Anyone have an ond1 scanner i could use. Total shot in the dark as to if it would even make a difference but worth a shot i guess.

 

[blondejoncherokee]

The scanner i have doesnt do obd1. Anyone have an ond1 scanner i could use. Total shot in the dark as to if it would even make a difference but worth a shot i guess.

see my previous post, I have a snap on brick, MT2500, if I have the CHR1 adapter, you can borrow it.

 

[Johnnie Walker]

91 and 92 auto ecu should work. 93 to 95 is different.

 

[GordoSmasho]

Thank you sir

 

[BigKintheXJ]

this thing doesn't have a security system in it right? hows your tps?

 

[GordoSmasho]

Deffinately no security system. Im testing the tps today. Pulled one of the plugs and its barely sparking on the diode. Not even really arking so im grabbing some new plugs right now.

 

[GordoSmasho]

Ok so i swapped the plugs and gapped them all properly. No change

Tesped the tps

This is the voltage input

Voltage output throttle closed

Voltage output wot

Wot seems to be out of spec but closed throttle is in spec. I have a solid ground at the plug btw.

 

[blondejoncherokee]

you already did the CPS and the coil?
want to list out the parts you need to try out? I might have a coil maybe.

 

[GordoSmasho]

The coil is throwing spark almost 5/8" off my screw driver in the plug boot and bright orange. Spark at the plug is greatly improved. But the spark is orange not white. Could be in need of a new coil but i have seen other jeeps running with much worse condition coil.

I have tested
Cps
Cam ps
Tps
Map

All test within spec with a questionable wot on the tps