Stumped

[mjdanico]

Good day folks, I have a 1988 GMC 3500 with a 350 TBI, a couple of months ago it would give trouble starting only when I wanted to come home at night ( blamed the boss) then it died a couple times on the road,threw a code for the TPS so changed it switched the fuel pump relay,cleaned TB checked fuel flow when it ran it ran fantastic finally changed the ignition module and it was cured for about 6 weeks then last weekend while at the dump it died had everything still in the back so started swaping out parts,found that if started at about 1/2 throtle it would stay running unplugged TPS and drove it home,can't get it to do it again and don't dare to drive it for fear of getting stranded,when it wouldn't run it had fire and fuel to the TB wondering if the new module went bad or there is another problem it has me scratching my head because you never know when or if it is going to quit,I was reading something about the magnet loosing it's charge could that be the problem? I don't know for sure but it could have as much a 300,000 miles on it different motor but same distributor......HELP ! in need it fixed because I will have to put up my 67 Impala soon for the winter.

[GMstrong]

Start by doing a full tune up plugs,wires,cap,rotor,coil.timing could be off alittle.

[mjdanico]

Start by doing a full tune up plugs,wires,cap,rotor,coil.timing could be off alittle.

Sorry it took so long Irene threw a wrench in to the works but have done all that and more completely rebuilt the distributor and checked values of sensors and it still starts great but stalls in 5 -9 seconds starts right back up and does it again I have by- passed the fuel pump relay and the oil pressure sensor to no avail, and the computer is still throwing a 12 code, my next step when time allows is to pull the computer and check for corrosion and continuity from the module plug

[GMstrong]

Did you replace the IAC valve yet?or the TPS?

[mjdanico]

Did you replace the IAC valve yet?or the TPS?

 

Yes with others I knew worked but still just the same it didn't change a thing so I have sort of ruled them out I have also tried it without the TPS pluged in and the IAC works when it runs long enough to go down to Idle before it quits,I have beat myself up over this because it has to be something simple I have even re-done grounds cleaned everything to the point where you could eat of it.

[GMstrong]

If its non of teh sensors uptop and the fuel injectors are spraying goodthe CTS sensor could do this to or a vacuum leak from the map sensor to the TB.Its either the ECM,crank position sensor.

[mjdanico]

If its non of teh sensors uptop and the fuel injectors are spraying goodthe CTS sensor could do this to or a vacuum leak from the map sensor to the TB.Its either the ECM,crank position sensor.

Hi, I think I have finally ruled out the electronics,it is hard to have something start and Stall while run around the door to try to see what is happening, after my nieghbor showed up and was able to watch a little better and also probed everthing for voltage and grounds again I dumped a little gas down her throat and it ran til it was gone then hot wired the fuel pump and it started and ran for a bit longer so I took the TBI apart and checked it out didn't find anything out of place or dirty but gave the regulator spring a little tug and lo and be hold it started and ran just as it used to I set the timing and let it warm up,then it began to rain so I shut it off and haven't tried it again yet but it is the first time it has run and stayed running in 3 weeks so I hope I have found the problem and the codes where being set as it would die out not because anything was bad but the engine was running out of gas and causing the computer to search for things. I want to thank you for your input and time and I hope this nightmare is over, Thanx again

[Mojavered]

Not sure if you ever got this licked or not, but did you try cleaning the TB? I had a similar problem on my 03. It would get all gummed up (maybe from the K&N oil on the filter?) and die. Good luck.