92 starts then stalls when warm only

[bracketshark]

My truck has developed this problem recently, when its cold it cranks and runs perfectly. It has problems occasioanly, when warm, the engine starts then stalls. The truck will crank again and go ahead and run,I can't figure it out. The plugs and wires are good, it has good fuel pressure, the fuel filter is new, the T/B has been disassembled and cleaned including the regulator. I've search the other threads and seen where the pickup in the distributor could affect this, I have a hard time beliving this is my problem giving how good it runs once it get started. No codes, any help appreciated.

[ctwright]

When you say cold and warm do you mean weather wise or vehicle wise?

[bracketshark]

I'm sorry, vehical temp at normal operating range it has problems cranking.

[redsaturn93]

I would put money on the coolant temp sensor. Not the one for the gauge the one that the computer reads.

[bracketshark]

Ok, I don't think thats the problem but I'll put an new one on it tommorrow and let you know. Thanks

[bracketshark]

New temp switch installed no differance noticed, it still takes 2 to 3 cranking times for it to keep running when the engine is warm.

[2000CAYukon]

You replaced the ECT in the intake manifold, right? The one in the drivers side cylinder head is for the gauge.

Since your issue is when the engine is warm, you could have a bad EGR valve (sticking) or a partial clogged exhaust.

A bad pickup will not throw a code. As the engine warms up, the idle is lower so the pickup could be an issue.

If you can, you should have it scanned. This will tell you a lot of what the sensors are seeing when it closed loop mode.

//2000CAYukon

[bracketshark]

Yes Sir I changed the ECT in the intake manifold. I put a new rear seal in the truck today and had the exhaust system completely removed and check the best we could for pluggage. It appears to be fine as is the egr. I've got a spare distributor that i 'm going to try soon. I'll post the outcome. Thanks

[bracketshark]

I replaced the distributor today and the same problem persist. Once the truck gets over the initial start it runs fine. Still no codes. Any more guesses? Thanks

[bracketshark]

I put a differant ignition coil on it today and a new set of 143ts plugs. If anything its worse. I guess I need to check the fuel pressure also, I never got around to that. Its not terrible to get started its just agrivating and all of a sudden started this mess. The truck will turn 4500 rpm everytime, I'm thinking it wouldn't run like that if the fuel pressure were low. Let me know if you have any suggestions. Thanks

[J-Ri]

Check the ignition module. I don't work on a lot of trucks, but it's very common on GM cars. With a scan tool, watch the CKP counter, if it stops, you have a bad CKP sensor. If it's good, with a test light, check for a flashing ground to the coil. If the flashing stops before the engine stops turning (may stop at a couple hundred RPM, that's fine), the module is bad. But you should check fuel pressure, although I doubt that's it. I had one come back and bite me by assuming fuel pressure was good once, so now I check fuel pressure every single time there's any running problem.

[bracketshark]

Originally Posted by J-Ri

Check the ignition module. I don't work on a lot of trucks, but it's very common on GM cars. With a scan tool, watch the CKP counter, if it stops, you have a bad CKP sensor. If it's good, with a test light, check for a flashing ground to the coil. If the flashing stops before the engine stops turning (may stop at a couple hundred RPM, that's fine), the module is bad. But you should check fuel pressure, although I doubt that's it. I had one come back and bite me by assuming fuel pressure was good once, so now I check fuel pressure every single time there's any running problem.

Well I got bit, It turned out to be low fuel pressure. I took the filter out and africanized a pressure gauge in there and found out I had less than 8 psi of fuel pressure, when cranking it only got to 8 psi after the motor started. I had to get a fuel pump from Advance because its Sunday but when it was installed I had ~14 psi cranking pressure. I've never seen one of these type pumps just get low on pressure, all I've seen ether work or don't. I learned my lesson, from now on a fuel pressure check it at the top of the list of first checks. Thanks to all that replied. I hope this thread helps someone along the way.