90 GMC starts and dies.

[74sundance]

Hey guy's I just had my truck in for an e-test and it failed, so I brought it home and set the timing to 0 deg and it passed like a new truck and runs perfect!...The next morning I went out to start the truck and it kept trying to start and then eventually did start but would die about 3-5 seconds later..It did this over and over.I finally got it running and made it to the gas station and pumped in $30.00 of fuel just in case my gas gauge had messed up and I was empty...The truck seemed to be fine but started acting up again while driving later that day.It acted as though it was out of fuel. I had to flutter the gas pedal to keep it running or it would bog and chug and try to die.Then suddenly it was fine again....Now today it would start and die again so I had some parts kicking around and started swapping but it made no difference.... Long story short, the truck will now run but only with the timing wire unplugged (The one you unplug when setting the timing) I took it for a drive and other than the engine light and smelly exhaust it seems fine.But once I plug the computer timing wire back in it starts and dies like before.Any one care to shed some light on this?

 

[cudajunction]

From my experiance working for GM in that era its either the ecm prom or the ecm itself when it does that.

 

[74sundance]

Got it, it was the Idle air control.Runs like a top now.Thank's though

 

[74sundance]

CRAP!! Don't got it lol...I went out today to start the truck to go buy a rototiller and it started and died.I guess I just got lucky yesterday when it started and ran.

 

[70rr-brian]

Does the computer tell you anything? Or does it even have one? Thing have fuel pressure? Possible fuel filter?

 

[65DODGE]

egr valve?

 

[74sundance]

I'm in the middle of pulling the EGR rite now...I'll let you know.I should add it will keep running if I spray carb cleaner in it,and that's odd because the fuel sprays the whole time rite until it dies.

 

[74sundance]

EGR is good....I thought I'd hit the intake again with carb cleaner and this time the prick kept running.I stuck a vac gauge on the intake when hot and got a steady 19 at idle and 17 in gear break on.When it was really hot I got a slight flutter in the needle.I'm not low on any fluids and they are not mixing and no white smoke and now every time I soak the back pass side corner of the intake down and then go and start it it will run fine until I shut it off and let it cool then I have to give it another blast to start it and run and drive all day lol

 

[74sundance]

Does the computer tell you anything? Or does it even have one? Thing have fuel pressure? Possible fuel filter?

No codes/lights it starts up perfect runs perfect and then just dies,no chugging no bogging.It's just like you turned the key off.

 

[Ron 73]

You said the exhaust smelled bad sundance, like rotton eggs?

Think i better explain the question, until a while back i thought someone was actually pulling my leg, I went thru everything like your doing now, couldn't find the solution, i was told it WAS, not could be the cat-converter, believe this or not took it off and bought new one after driving it and finding the guy was not pulling my leg. sound goofy, well i thought the same, but i do believe it now. the converter wasn't that old but it must have been faulty..

 

[74sundance]

You said the exhaust smelled bad sundance, like rotton eggs?

Think i better explain the question, until a while back i thought someone was actually pulling my leg, I went thru everything like your doing now, couldn't find the solution, i was told it WAS, not could be the cat-converter, believe this or not took it off and bought new one after driving it and finding the guy was not pulling my leg. sound goofy, well i thought the same, but i do believe it now. the converter wasn't that old but it must have been faulty..

Oh sorry Ron I forgot to say it only smelled bad when I had the timing wire unhooked...It smells like normal 1990's exhaust now lol....But your rite a cat will cause that smell.

 

[Ron 73]

Ok, i debated with myself as to put that in, Wife's 2001 Malibu and your pickup must be related with a lot of the problems were having, It sounds almost like a vacuum leak but only when its hot, could you have a problem with the intake, after it cools down your spraying it to get it running, wouldn't it have to be sucking air? The only other thing working on hers i can think of is the ignition, something getting hot and shutting it down, but if that you wouldn't have to spray the intake... Im just guessing here with this, working on hers is a challenge enough, its to late to call a buddy of mine up that works on these but if the problems still here in the AM ill see if i can get some information for you. Good luck.

 

[Ron 73]

Well sundance hear is 3 things to check, one he said you have already done the EGR the second is the fuel pressure, the third is he said the distributors are known to ware out look for play in it and theres supposed to be 2 wires under the pick up module that the coating likes to break on them and short out, sometimes it will run good then it wont. If you spray the carb cleaner back there and it will run i cant see how all this could be, but i guess you could check on it, he said sometimes when the timing is reset unplugging whatever wires start the problems with it. i have no idea if this will help, maybe someone else hear can help. I do wish you luck i see your having one of those Murphy law weeks.. Hope this helps.

 

[74sundance]

Well sundance hear is 3 things to check, one he said you have already done the EGR the second is the fuel pressure, the third is he said the distributors are known to ware out look for play in it and theres supposed to be 2 wires under the pick up module that the coating likes to break on them and short out, sometimes it will run good then it wont. If you spray the carb cleaner back there and it will run i cant see how all this could be, but i guess you could check on it, he said sometimes when the timing is reset unplugging whatever wires start the problems with it. i have no idea if this will help, maybe someone else hear can help. I do wish you luck i see your having one of those Murphy law weeks.. Hope this helps.

I replaced the distributor when I did my e-test.The next morning all this started so I put the old one back in lol.I changed out the module in the back of the distributor still no luck.

 

[74sundance]

Ok, i debated with myself as to put that in, Wife's 2001 Malibu and your pickup must be related with a lot of the problems were having, It sounds almost like a vacuum leak but only when its hot, could you have a problem with the intake, after it cools down your spraying it to get it running, wouldn't it have to be sucking air? The only other thing working on hers i can think of is the ignition, something getting hot and shutting it down, but if that you wouldn't have to spray the intake... Im just guessing here with this, working on hers is a challenge enough, its to late to call a buddy of mine up that works on these but if the problems still here in the AM ill see if i can get some information for you. Good luck.

Hey Ron, if your wife's car dies when hot change your temp sensor, it's telling the computer your over heating and it shuts the car down.Be care full it might have a temp sensor and a temp sending unit(controls the gauge in the car)....If you can't tell them apart go to the parts store and buy the "temp sensor" and match it up with the 1 you have and change it.

 

[74sundance]

If it wasn't for the fact that I changed the IAC I'd say it was the problem with my truck...Arggg lol

Start and Stall
Most IAC failures manifest themselves as a start-and-stall condition. Generally speaking, the engine will catch and run for a second or two, stutter and die. IAC-related start-and-stop conditions can be easily differentiated from fuel-related issues; during IAC-related stalling, applying throttle in light pulses may prolong engine failure, but will not prevent it. Applying throttle while facing fuel-related failure will result in immediate stalling.
That is my problem to a capital "T"

 

[69rtse4spd]

Is this a T.B.I. motor, my 88 had one of the wires on one of the T.B.I.s getting pinched, would not send a fuel signal to it. Also on the tilt wheel, the wirering was getting pinched & shorted (white wire) do not remember what it caused but they do not give you much wire to work with. Also the temp. sender on the front of the intake, the two wires came lose inside the connector. This told the computer the motor was running hot, which leaned out the A/F so much trucked died, cooled down, started back up. Do not know if any of this helps but who knows. Work at the Ft. Wayne Truck & Bus plant, might have built your truck here.

 

[74sundance]

Is this a T.B.I. motor, my 88 had one of the wires on one of the T.B.I.s getting pinched, would not send a fuel signal to it. Also on the tilt wheel, the wirering was getting pinched & shorted (white wire) do not remember what it caused but they do not give you much wire to work with. Also the temp. sender on the front of the intake, the two wires came lose inside the connector. This told the computer the motor was running hot, which leaned out the A/F so much trucked died, cooled down, started back up. Do not know if any of this helps but who knows. Work at the Ft. Wayne Truck & Bus plant, might have built your truck here.

SO it's your fault!!!

lol Just kidding....Still no luck with the truck but I will check out the column and the ecm tomorrow.It is TBI.

 

[74sundance]

This is an old one but,,,,,,,I got 2 faulty fuel pumps from the bone yard that's what was wrong with the old girl.I finally cracked and put a new unit in and all is good.

 

[snakeyes]

didn`t notice this post before was going to suggest fuel pump I had the same thing happen on my old 91 chev. truck ,mine happened just after I left the dam echeck place,had it flat bedded home pulled the bed back and changed in a dam snow storm ,:angry1: