89 C1500 running problem - Looking for ideas

Looking for ideas on the problem I am having with my '89 C1500. I've had it since new and now it shows like 306K miles. it is a TBI 350.

It has been sitting for about 18 months and I've decided I need to get it going again.

It is getting good gas pressure and good spark and starts well. But after about 8 - 10 minutes it shuts off. Let it cool down for 4-5 hours and it will repeat the process.

Codes? We don't get no stinking codes! I'm thinking now that maybe it is the temp coolant sensor. There are two of them. One on the manifold and one on the left head. Any ideas which one might be the culprit if it is indeed the sensor?

Anyone care to throw some ideas what to go to next?

TIA

Check your ignition module (ICM). Take off the distributor cap, carefully pull of the rotor and remove the ICM, take it to advance-o-zone and have them test it and go from there. Usually when they fail it's once the truck is up to operating tempature so it may test good at the parts store. If you have a known good ICM to swap out it's a quick and easy way to check if it's the problem, swap in a good one and if it doesn't stall than that was the culprit. When they fail they will not throw a code. Some other parts in the chain (bad MAF, bad TPS, it's not really much to deal with) will throw a code.

Temp sensor in head is gauge only. I have similar issue with my tbi 350 roadmonster, next step for me is ignition module. It also sat a long time.

In reply to patgizz and 06HHR Thanks for the ideas. Still stumped and no codes.

The original coil was shorting out against the steel braided fuel line. It had been rubbing against it for who knows how long. I got a new coil from O'Reilly. I put in the new coil and the new Ignition module I got from Rock Auto and it wouldn't start at all. I put the original ignition module back in and it ran -for 10 minutes or so - until temp came up.

Bought a new ignition module from O'reillys today and it ran for about 10 minutes. Same story - ran until it got up to temp.

How do you feel about maybe the temp sensor? Anything else?

Thanks

Only reason I don't think it's the temp sensor is when those quit, the result is usually black smoke out the exhaust and your MPG takes a nosedive into single digits. My understanding is that signal is used to adjust the fuel delivery by the injectors. They rarely cause a shutdown/no-start condition with an OBD0 or OBD1 vehicle in my experience, which isn't much (not a professional wrench and didn't sleep in a Holiday Inn last night). I've seen a bad MAP sensor cause that condition, but that usually throws a code. Could be a fuel issue, fuel pump relay going out or a bad injector driver in the ECM but all of those are WAGs at this point. When is the last time you changed the fuel filter BTW? I've seen that cause problems as well

My 90 did the same thing with a plugged fuel filter.

How did you verify the fuel pressure? Mine did this and it was a bad fuel pump. Would run on the richer trim in open loop, then die when closed loop kicked in.

second guess is bad O2 sensor. unplug it and see what happens.

Thank you all for the suggestions. It finally threw a code - 15 -CTS.
Beginning of March I had stuck a hose with an electric fuel pump and sucked as much of the old gas out of it as I could. I put in fresh gas and changed the fuel filter 3 weeks ago. To verify the fuel pressure I did what every other serious shade tree mechanic would do - 'Hey look! Gas is coming out of the injectors!" The spray is a nice cone shape. I don't have a pressure gauge.

Thanks for the suggestions. I replaced the CTS and it idled for 25 minutes. Then I drove it around the block and it didn't cut off. May be fixed!

Glad to hear!