'93 5.7 Starts And Stalls

pym · June 22, 2008

I have a '93 GMC van 3500 with a 5.7 engine. When I start my truck, it will start and stall after a few (2 to 5) seconds. It will do this several (10 - 20) times before finally starting for good, then I'm good for the day.

The problem does not seem to be fuel, more likely ignition... But i'm not sure where to look first ?

I have an other problem that 'might' be related... When the truck is running and I turn on the headlights, everything cuts out... Engine, radio.... If the engine was at idle, it will most likely stall, if it's reved up than it will studder and keep going...

Any ideas ?!?

Thanks

PYM

merlin5577 · June 22, 2008

With the information you have given the first thing I would check is the throttle position sensor. If the TPS is faulty the engine doesnt know how much air is going in so it cant accurately add a correct amount of fuel. On the newer trucks the mass air sensor would compensate for this but on your TBI truck no such luck.

As for your electrical issue my guess would be the alternator is not putting out enough power for all your needs. When you turn the lights on your pulling more electricity then is available so the engine stalls. Again this is only a guess.

kuhl_530 · June 22, 2008

now wait, before you go out and get a new altenator, check your battery terminals for corossion and clean accordingly. Next check your engine ground strap (the one that runs from the engine to the body of the vehicle) to make sure it's secure. Then if that doesn't solve it, I'd look at the altenator.

merlin5577 · June 22, 2008

If the truck starts repeatedly that would pretty much rule out the battery cables. You might be on to something kuhl with the ground strap but I doubt it if it only happens when the headlights come on.

pym · June 23, 2008

i'm running 2 batteries on this truck. One is grounded to the engine, the other grounded to the chassis. I doubt that my problem is caused by lack of electrical power.. BUT I will check the ground strap... we never know!

for my main problem... if the TPS was bad wouldn't the check engine light turn on ? And once the track runs, I can drive it without any problems...

PYM

merlin5577 · June 23, 2008

The TPS is probably not faulty. It is probably just worn out and takes longer then normal to report an accurate signal to the trucks PCM. But as I said before this is just an educated guess. Without looking at the truck myself I cant give you a definate answer.

Your electrical problem is caused by a lack of power. The problem is, where is the electricity going? The batteries in a vehicle are only there to start the vehicle and occasionally take up the slack from the alternator it is isnt putting enough power out. My guess is that the power is going to a ground (short) instead of going where it is needed. The best advice I can give you PYM is get a good voltometer (if you do your own electrical work) and figure out where the electricity is going when the lights are on. Or take it to a shop that specializes in electrical problems and let them take care of it. Good luck.