[Jayce Gravdahl]

Hello All,

My '93 Suburban (5.7) dies randomly while I'm driving. It will be running just fine, and then the RPM will just drop to zero. No stuttering, all the lights stay on, it's like nothing happened. I'll coast off the road, sit a minute or two and it will start right up again. If I try to start it immediately after it dies it will just spin over. Truck only has 120k and has been the least reliable vehicle I have ever experienced, leaving me stranded multiple places multiple times.

I've replaced the ignition control module, ignition coil, pickup coil, fuel pump, fuel pump relay and nothing seems to have permanently fixed it.

It died completely on me and wouldn't start back up again a while back, this is when I replaced the pickup coil and got that problem fixed. The symptoms are the exact same now as when the pickup coil went out on me, driving along, engine kills, everything still running, except it will start back up for me this time.

I've read multiple threads describing similar issues, however all seem to be solved with parts that I've already replaced. Any new insights/perspectives are much appreciated. Thanks in advance!

 

[geo1]

Ok,what are you losing? Fuel or spark,can you hear pump running when issue happens?

 

[Jayce Gravdahl]

Can't hear the pump but that's only because it dies driving down the road when I wouldn't be able to hear the pump anyways. There's absolutely no stumbling when it dies and fuel system components are all new which leads me to believe it's spark but I may be missing something.

 

[geo1]

So every time it starts right back up?how does body side of connection at fuel pump relay look, clean?what about injector connections?and grounds on motor?

 

[Jayce Gravdahl]

Yes, like clockwork. Relay connection super clean, will check injector connections and grounds this afternoon. Thanks for the responses, will update in a few hours..

 

[geo1]

One more, while it's idling, wiggle harness,by starter ,maybe a fusable link down there is failing? green fungus at either end is a possibility

 

[Jayce Gravdahl]

Never heard of that one... new insights are great. Thanks geo.

 

[thegawd]

you replaced all those expensive parts but what about the cheap or free ones... ground straps? theres 3, one from neg on battery to fender, one from the frame to passanger side back of the engine block and same point on the frame to the firewall. if 2/3 are really bad or nonexistent you my get some functions but not all... bad grounds do strange things.

Al

 

[Sawfish]

Could be vapor lock if you are running in hot weather. Mine did the same think and it was the water pump going bad.

 

[RayVoy]

We can do a lot of guessing here, my guess is the ignition switch.

Note: the OP doesn't care, last time on was the day after the first post.

@Jayce Gravdahl get this fixed?

 

[Jayce Gravdahl]

@RayVoy Think so.

Grounds were good, replaced the ignition switch, still kept dying.

Replaced the Ignition Control Module for the 4th time in a couple years and it seems to have been solved. Lesson learned, don't buy the cheap chinese ICMs that melt down in a couple thousand miles.

 

[Cowboytrukr]

Thanks for posting back, Jayce. Just to confirm, you applied heat sink conductive grease on the ICM, right?

 

[RayVoy]

Hey Jayce, glad your back, glad you got it fixed.

Hang around, lots of good people on here!

 

[Jayce Gravdahl]

@Cowboytrukr yes, but I would usually just use the little bit that came in the package... barely enough to even get a full layer on it. This time I went and bought a big tube of dielectric grease and caked it on.

@RayVoy will do! Sorry for not posting the update earlier, hadn't driven it enough to be confident that it was truly fixed.

Cheers!

 

[Cowboytrukr]

Jayce, I’m not sure you caught what I was saying. There’s a distinct difference between dielectric grease and heat sink grease. One is conductive and one is insulating.

Dielectric is insulating.
The ICM needs heat sink grease.