Help!!! Shutting off issue

[Matt Conner]

I agree with Schurkey most likely when the engine gets warm and goes into closed loop operation not having the O2 the engine ECU will most likely lean out or richen up until it stalls.

It doesn’t just stall out, it straight up shuts off, like if someone were to turn off the key

 

[texas tough]

will it stall out after idling in park or just driving.. one time I had a positive battery cable that was grounding to the frame, and it would stall the truck.

 

[Matt Conner]

will it stall out after idling in park or just driving.. one time I had a positive battery cable that was grounding to the frame, and it would stall the truck.

It’s a manual trans. It will just shut off after 15-20 mins of idling or driving. Not a stall but a shut down just like someone turned off the key

 

[Wrench]

The truck doesn’t have any o2 sensors on it. It only had one on it and when I had the exhaust put on they took the one out.

I was banking toward cps/kps failure. Codes would help with that diag.

I'd put those ******** back in if I were you. TBI is no fuel injection but it still takes readings from the ECU,
(02 sensors) don't fix what ain't broke lol

 

[Matt Conner]

I was banking toward cps/kps failure. Codes would help with that diag.

I'd put those ******** back in if I were you. TBI is no fuel injection but it still takes readings from the ECU,
(02 sensors) don't fix what ain't broke lol

I don’t have a way to read codes other than the old paper clip trick

 

[Schurkey]

I don’t have a way to read codes other than the old paper clip trick

Screw "codes".

Codes can be helpful, but you need access to the data stream. That means a REAL scan tool, not a piece-of-crap code-reader or a paper-clip.

You can fight this for weeks, throw a bunch of random parts at it...but if you want it fixed without wasting time, money, effort, and enthusiasm, you need better intel into what's wrong. That's what the data stream provides.

Again, we KNOW that the computer isn't getting O2 info; so that's GOT to be on the list of things to fix.

I'd like to know what the fuel pressure is when it stalls.

 

[stutaeng]

Yeah, that sucks changing all of those parts. I'm not familiar with the 88-95 era, but I'm guessing live stream data shows up much like the 96+?

My brother has a '90 C1500 and he had a missfire at idle that he chased for weeks. He changed all sorts of parts, with no change. I finally told him to just take it to a shop and it was the distributor cap and rotor. Not sure how shop made the call, but problem solved. I joked and told him a $30 part becomes a $300+ repair bill.

Half of the battle of a mechanic is diagnosing the problem. Unlike brakes, suspensions, hydraulics, etc., electrical problems can be a nightmare. A simple test light and a wiring diagram are your friends. A digital voltmeter/ohmmeter comes in really handy too. I really like to find conclusive tests to confirm a sensor is "bad" before condemning it. You need to think like the ECU.

Fuel pressure gauge is a must also. I can't tell you how many times I've gotten a crank, no-start conditions suspecting it was fuel pressure. A simple gauge confirms I have fuel pressure within specs. and I keep hunting.

Good luck.

 

[89GMCJOHN]

I can only add my two experiences like this ,,,,,,,usually when its sudden lights out - like someone literally shuts the engine off suddenly - its been ignition module related ...replace the module with a good ole USA module and I was good to go...... one time however I had a wiring harness issue where the +12 I was supplying the ignition with would start out at 12 volts fine but heat up after 20-30 minutes of driving , build up resistance and slowly drop down to 8-9 vdc and immediately kill the ignition. When it died there was no stumbling , wheezing or fight to keep itself running. It was just like BAM - someone simply shut the key off - sudden death . I watched the +12 line with a volt meter balanced up on the outside of the windshield , drove it , heated things up and and saw it slowly reduce in voltage for myself on the meter. If I turned my bright headlights on I could make the harness heat up quicker and kill it ....I moved that +12 supply wire to a better source and it never ever died on me again for the rest of the time I owned it . My suggestion watch your +12 supply line to your distributor until your magical 15 -20 minute mark and it heats up and dies to rule that voltage line out out of the equation . Good luck .

 

[McBroom]

^^^^awesome advice ^^^^

The Blue Mule

 

[Matt Conner]

I can only add my two experiences like this ,,,,,,,usually when its sudden lights out - like someone literally shuts if off suddenly its been ignition module related ...replace the module with a good ole USA module and I was good to go...... one time however I had a wiring harness issue where the +12 I was supplying the ignition with would start out at 12 volts fine but heat up after 20-30 minutes of driving , build up resistance and slowly drop down to 8-9 vdc and immediately kill the ignition. I watched it with a volt meter balanced up on the windshield , drove it , heated things up and and saw it for myself. If I turned my brights on I could make the harness heat up quicker and kill it ....I moved that +12 supply wire to a better source and it never ever died on me again for the rest of the time I owned it . My suggestion watch your +12 supply line to your distributor until it heats up and dies to rule that out . Good luck .

I will check those 12v lines coming into the distributor, appreciate the advice