h6294443

Help!!! I bought a 97 Blazer 4x4 three weeks ago. Nothing but trouble.
After having it for 2 hours, the power brake booster went out. Well, I replaced it myself. Then I had to replace the battery. After that, one of the big starter bolts broke off in the block, because the other one had worked itself loose. At this point, I had it towed back to the dealer and told them to fix it. That was 22 hours after I bought it. They replaced the starter, and they had to replace the flexplate too. After they were done, my wife picked it up and made it three blocks before having it towed back to the dealer. Well, turns out they damaged the coil wire, so they fixed that. Since then (about three weeks ago), the vehicle drives fine, except.....
Every weekend, while driving in city traffic, the engine will stall. Out of nowhere, the engine is dead. All the lights come on. The radio never goes out, so it is not the "run" wire from the ignition, I figure. I suspect something electrical. Seems to happen when underhood temperature is hot, but that is only a guess. The computer does not set a troublecode. After it dies, it is hard to start. I need to wait 5 to 10 seconds, then it will start. It only happens on the weekend, after a bit of driving. And once it happens, it happens every two minutes, with the frequency increasing the more it happens. If I let it sit for half hour or more, it will be fine (for a while anyway). Any ideas out there?

GMMerlin

When the engine dies. does it spin and not start or just wont spin over?
If it spins and doesn't start.
You could have a coil or module going open when they get hot. Check for spark. Also pay close attention to the small wires going into the coil. They will break inside the insulation and cause an intermittant problem.
Also I have seen some fuel pumps causing problems like this. Check fuel pressure.
Also I have seen some ignition switches causing some intermittant stall/no start problems.

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h6294443

Thanks for your reply. The engine turns over just fine when I try to start it after it dies. It just doesn't start, like there is no spark. I checked the wire run under the black cover above the break booster. When I disconnect the big pastic connector that's in there, I get the same result. Everything has power, engine turns over, but it does not start. So I put some di-electric grease on the connector. I will drive it for a while and see if it helped. I will let you know.

h6294443

Yeah, one more thing I forgot: I have jiggled the control wires for the coil and the coil driver while the engine is running, no effect. So I assume those wires are fine. I have done resistance checks on the coil and compared them to a brand new coil at schucks. Those readings were identical.

GMMerlin

Next thing to do is check for the presence of spark and fuel pressure.

__________________
Why do you never have enough time or money to do the job right the first time, but enough time and money to do it again?
Got all the certifications
25 years ASE Certified Master Technician
GM WCT
Yea..I work at a DEALERSHIP....got a problem with that?

Want to diagnose cars like the Pros? FOR SALE: OTC Perception 2 channel Labscope (badged as a Matco Reality)
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h6294443

I will go ahead and check the fuel pressure. But....since this happens so rarely, and only for 5 to 10 seconds, would checking for spark do any good? Or fuel pressure, for that matter?

GMMerlin

Since your window of opprotunity is limited, I would check both. Spark would be easier because you can pull a plug wire or the coil wire off rather quickly and then spin the engine over.

At the shop (dealer and home) I'll drive a vehicle like that with a fuel pressure gage taped to the winshield and all my test equipment in the front seat ready to go.

__________________
Why do you never have enough time or money to do the job right the first time, but enough time and money to do it again?
Got all the certifications
25 years ASE Certified Master Technician
GM WCT
Yea..I work at a DEALERSHIP....got a problem with that?

Want to diagnose cars like the Pros? FOR SALE: OTC Perception 2 channel Labscope (badged as a Matco Reality)
This is my personal labscope that I use to diagnose waveforms, like new, comes with leads and training video
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h6294443

Alright, I think I may have it fixed.
I noticed yesterday that the stalling would occur after a bit of driving, in hot weather. I read a previous post about adding cold gas to the hot tank. So I did that. And guess what? No more stalling. Until the tank warmed up again. Now, I admit that it may not be the gas temperature but rather the amount of gas of tank and the positive head on the pump. Either way, the pump had to go. Here came the ridiculuous part: 381 dollars. Oh well. That tank was a pain to get out, and a pain to get back in. I drove it, and couldn't believe it. The truck seems to have twice as much power as it did before. And the old pump had some bad looking contacts on the connectors inside the tank. So I assume my problem is fixed. Until next time that is.