Runs good for 20 minutes, then dies and won't start until the next day

[whoaskew]

I am sick of my truck leaving me stranded.

It is a 1991 C1500 2wd, ext cab, short bed 5.7L engine with about 300k miles on it that I have had for a year. Supposedly a different 350 engine and transmission was put in a couple years ago.

This problem has been going on for 2 weeks. I'll start the car up and it runs just fine, no problems. After driving for about 20 minutes, the engine will die while driving, and will not start back up until the next day. I have sat in the car for literally 4 hours patiently waiting for it to start. I'll turn the key and the engine will rotate, but will not start. When someone shows up to give me a jump after the battery gets low, it will not start. I'll go home and go to sleep, and sometime the next day I'll go to my truck, and it will start back up, and I'll drive back home, and I'll make it as long as it takes less than 20 minutes.

It is not just a "morning problem", but a "first time I have started the truck that day" kind of problem. Last week, it happened to me in the mornings. On Saturday, I didn't leave my house until 2pm and the problem happened. Today, I first drove it at 8pm, and the problem happened.

Things I have changed so far (mostly from Autozone):

Starter - burnt it out when it first died 2 weeks ago, now I know not to crank when below 9 volts - lifetime warranty

Spark plugs - no more engine popping or driving with 2 feet - changed last week on Tuesday - AC Delco CR43TS gapped at .035

plug wires - changed all in November, since I noticed one of the old ones was tore - lifetime warranty

Distributor cap and rotor - changed last month when the engine started popping - autozone

Ignition control module- I changed today, I really thought that would fix the problem after speaking with the Autozone guy - lifetime warranty

Ignition Coil - changed last month because of popping

Fuel Filter - changed last Thursday, thinking it was a fuel problem



Here are some of the other symptoms I have been noticing over the last couple months:

Pretty bad gas mileage, I know it is a V8, but it is just as thirsty when I am not carrying anything as when I am pulling a car

A couple months ago, after driving for about 30 minutes or so, the engine would make a "Pfft" noise and would start popping and I would have to drive with 2 feet to keep the engine running.

[jdl]

Did you do any testing, when the vehicle refused to start? Yes, if your by yourself, not much you can do. If it cranks good but, won't start, have a helper crank it, while you visually check for spark at the plugs. If spark everywhere, use a gage and check fuel pressure. Any applicable trouble codes? Can you visually see injector spray pattern, TBI, engine cranking? If you see a spray pattern, that doesn't mean the pressure is good.

The popping noise, might be a timing issue?

[whoaskew]

Today I started the car and let it run in front of my house. I gave it a little gas while it was running and it died after 15 minutes.

I pulled off the spark plug wire closest to the front of the car on the drivers side. I layed the wire on top of the valve cover with a small screwdriver stuck in it. I had a friend try to start the truck and I saw a spark from the screwdriver to the intake.

I came back here to post this update, then I re-read your reply and noticed you suggested I check for spark EVERYWHERE, and I only checked one plug wire.

I guess I'll have to check the other 7 in the morning since it is already dark outside.

I don't know how to check fuel pressure or for trouble codes, but I'll do a search for instructions.

[2000CAYukon]

Take off the air cleaner and have a friend try to start it and see if the injectors are spraying fuel.

A few months ago, I have an ignition module go bad on my 90 K1500. Even though the ignition module was bad, the injectors were spraying fuel.

There is no service port on the TBI fuel lines so you need a special tool to check the fuel pressure.

//2000CAYukon

[whoaskew]

Ok, I'll check the injectors in the morning.

I took off the ingnition control module yesterday, thinking it was the cause of my problem. I took it to Autozone tested it, and it failed every test, I think there were 7 or 8 tests in all.

I bought the new one for $42 and put it on last night, but the truck still died on me after 20 minutes of driving - the exact same problem, so replacing the control module didn't fix it.

[jdl]

The autostores sells a TBI fuel pressure gage, you just tee into the supply line. Sometimes it is easier for me to tee in at the fuel filter. Years ago, when my oldest boy got his first car, it was tbi, I made a fuel pressure gage to tee into his system. It worked fine, still have it. To check for codes, you place jumper wire between A & B terminals of datalink connector. Turn the key just till the dash lites come on, no further. The mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

[whoaskew]

Originally Posted by jdl

To check for codes, you place jumper wire between A & B terminals of datalink connector. Turn the key just till the dash lites come on, no further. The mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

It gave me a code 12 - so I guess no problems there.

[Scrapper]

have you tryed putting a new picup coil in dist? or maybe your cat's pluged?

[whoaskew]

When it died, I cranked the engine and the injectors were still squirting fuel just like before. I don't have a pressure gauge, but it seems like the pump is working.

I checked the wires on the drivers side when it died and they all sparked but I still need to check the passenger side.

Funny thing is it is taking less time to start up after it dies, maybe weather related since it is 70 degrees today and it has been in the 30-40 degree range for the last few months.

I am starting to think the problem might not be a lack of fuel or lack of spark but maybe too much fuel- meaning the engine is getting flooded. Is that a possibility?

[whoaskew]

The passenger's side wires have spark too. I did notice that the passenger side valve cover has an opening in it where something obviously is supposed to be sticking in there. Would that be for the pcv valve? Could that be related to the engine dying on me?

[2000CAYukon]

The Engine Coolant Temp Sensor (located in the intake manifold near the tstat) tells the ECM what temp the engine is so that the ECM can control the amount of fuel to the engine.

With the engine warm, it should read around 100 ohms. If it is telling the ECM that your engine is cold but it is really warm, it can cause it to run poorly.

Usually, if the ECT sensor was bad, the truck would restart after the engine cooled down.

I wonder if the cat is plugged. You should remove the 02 sensor from the exhaust manifold and try to start it.

You may have some kind of heat soak issue. Is the spark a good blue spark?

//2000CAYukon

[whoaskew]

Originally Posted by Scrapper

have you tryed putting a new picup coil in dist? or maybe your cat's pluged?

No, I haven't tried the pickup coil

[whoaskew]

Originally Posted by 2000CAYukon

The Engine Coolant Temp Sensor (located in the intake manifold near the tstat) tells the ECM what temp the engine is so that the ECM can control the amount of fuel to the engine.

With the engine warm, it should read around 100 ohms. If it is telling the ECM that your engine is cold but it is really warm, it can cause it to run poorly.

Usually, if the ECT sensor was bad, the truck would restart after the engine cooled down.

I wonder if the cat is plugged. You should remove the 02 sensor from the exhaust manifold and try to start it.

You may have some kind of heat soak issue. Is the spark a good blue spark?

//2000CAYukon

This is my first time doing this so I don't know what a good spark would look like, but I did expect the spark to be bigger.

Can I just unplug the 02 sensor or do I have to actually remove it?

[2000CAYukon]

If the cat is plugged, it will usually run if you remove the 02 sensor. Just unplugging won't help.

//2000CAYukon

[2000CAYukon]

Since it runs for 20 minutes, see what the spark looks like in the morning and compare to what it looks like when it does not run.

//2000CAYukon