Randomly shuts off, then restarts after it sits for an hour or 2?

[letitsnow]

Am on a vacation trip, pulling camper. Stopped at a gas station and filled up. Drove into the back lot to eat lunch and the truck dies while idling, would crank but not start. After sitting for an hour or 2 it started back up and seemed fine. We start driving down the freeway, all seems normal, driving along and the truck acts like you just shut it off. I coast to the side of the road and stop.

I hook up my scanner and there are no trouble codes. The engine temp reading makes sense. The tps reacts to the pedal moving. The motor never got hot. It was running awesome until it just stopped. The motor cranks over, but no start...

-I changed the icm, no difference.
-I changed distributor cap and rotor, no difference.
-I changed ecm, no difference.
-fuel pressure is still 60 with key on, 56+ while running (same as it always has been).

After sitting for a couple hours, waiting for the tow truck it fires up. I drove (pulling the camper) to the next rv park and checked in.

Any ideas on what to check next?

 

[Frank Enstein]

Fuel filter and/or fuel pump?

My guess is maybe a bad batch of fuel. If there is water in the fuel and it got to the injectors it will stall.

Remove the filter and shake it out on a non porous surface. Any water will bead up. If so some dry gas may help. Try to get the kind that contains isopropanol.

 

[SUBURBAN5]

You have a 5.7 vortec right?

 

[letitsnow]

You have a 5.7 vortec right?

Yes

 

[letitsnow]

Fuel filter and/or fuel pump?

My guess is maybe a bad batch of fuel. If there is water in the fuel and it got to the injectors it will stall.

Remove the filter and shake it out on a non porous surface. Any water will bead up. If so some dry gas may help. Try to get the kind that contains isopropanol.

Wouldn't it chug or hesitate (at least a little), if it was bad gas? This just shut off like you had turned the key/ignition off.

 

[letitsnow]

While this is a pain in the butt, I have nowhere to be for the next month, and am comfortable here. I am also traveling with some tools and spare parts.

I have a new coil with, but some wonderful gm engineer thought it best to rivet the coil on.... I do have a grinder with, but haven't done that job yet. Still looking for an engineer to punch first, then I will feel better haha.

 

[letitsnow]

^^^ With that said - the next truck that I build will be a manual fuel pump, carbed 454 with hei and manual valve body 4l80.

 

[stutaeng]

Well, fuel delivery I think you can rule out with the fuel pressure you have. The fuel pressure did hold steady, right? It should hold within 1-2 psi of initial pressure for about 15 minutes.


I think I would be checking to see if you have spark next with those little adjustable gap spark tester. But I can't see why you would have spark one time and then lose it the next time. How old is your distributor?

 

[letitsnow]

Well, fuel delivery I think you can rule out with the fuel pressure you have. The fuel pressure did hold steady, right? It should hold within 1-2 psi of initial pressure for about 15 minutes.


I think I would be checking to see if you have spark next with those little adjustable gap spark tester. But I can't see why you would have spark one time and then lose it the next time. How old is your distributor?

The fuel pressure held the same as it always has. I typically check stuff like this while at home every month or two - that way I know what this trucks normal is.

The distributor is probably the original, with 234,000 miles on the truck. When I grab the rotor (with dist cap off, there doesn't seem to be any excessive play.

 

[letitsnow]

I don't have a spark tester. I will buy one now though.