My 2002 GMC Savanah van's 5.7 L engine stalls with no warning when operating. Techs can't find problem. Help ?

Question

The problem does not happen every time I drive the van, never know when it will act up. If I let it sit for awhile, it starts up again.
This has happened at the service center but they are still unable to find anything with diagnostics.

Answer 1

Sounds like the "techs" aren't trying very hard, or else they're clueless. An intermittent problem like yours is admittedly much harder than usual to solve, but still needs to be approached in a logical step by step manner. If all they're doing is looking for codes, then I sure hope you didn't give them any money. If you see anyone at that place with a MODIS or Vantage Pro, go and talk to them right away. Just using the Tech II isn't gonna get it done. Use the low amp probe on the fuel pump relay, that's AMP not volts, display that trace (channel 1) with the fuel pressure (channel 2) and go for a test drive. Look for jagged commutator spikes consistent with pressure fluctuations. This will give you an idea of pump condition, and on the off chance the failure occurs on the test drive, the evidence will be right in front of you. Also, note that the check engine light (MIL) doesn't come on. Use channel 3 with the KV probe and graph the coil output. It could take some time, but waiting for the computer to figure it out instead of using any intelligence or training is just a crime. I never understand how these clowns call themselves "technicians" yet consistently fail to check the basics. Oh, and the quick and dirty way to monitor fuel press is just hook it to the rail, run the hose out of the hood, and zip tie the gauge to the wiper. Not pretty, but will show if you do have a major fuel issue. As for the ignition, use a see-thru tester that lights up. Can get them for 5 bucks, stick 2 of them on adjacent cylinders, then if the engine quits, have someone crank it while you look for the lights. Easy. Lemme know what happens. And as far as "jeep"'s answer, yes that could be a possibility with your vehicle, or a ground strap, or maybe not. If your engine quits with or without a drop in fuel presure, it will at least give you a place to start.

Answer 2

Wow this could be a tricky one to diag out, yet i will provide you some sturdy prevalent thought's the place to start up at. lots of the time if that's stalling out, does it do it after it has ran for awhile or merely every time. it this is doing it after it has ran for awhile i could suspect something interior the ignitions device getting heat, gasoline pump getting heat or the ecm internals over heating. in spite of if this is something that happens merely any ole time i could seek for grounds that are unfastened or cord connections that are no longer totally linked. some different issues i could additionally seek for in view that this could be a van could be adequate air bypass to the engine bay throughout the time of operation. in spite of if it is not getting adequate air bypass the engine bay to help the cooling ability of all of the neat little factors that are deliver at the same time on the engine and firewalls, it ought to reason a difficulty with overheating of those factors, which in turn ought to reason stalling, tough run circumstances and so on. different possibilities must be relays that grow to be overheated. like the gasoline pump relay.... desire this facilitates you out merely a sprint and sturdy success.

Answer 3

i m a tech at a gm dealership, and i m not trying to diagnos your van but this past week we had a 01 van with a similar problem and what i found was a faulty connection in the connector just before the fuel tank under the van. this caused the fuel pump to stop operating . hope this info helps.

Answer 4

take it to Hambone,he should be able to find it in no time! Good luck