Intermittent start

[oldgeeezer]

I have a 1998 Silverado, 5.7L Z71 4X4. It has intermittent start problems.I changed out the fuel pump, and still had the problem. No codes showed up at any time.

I did the usual troubleshooting and found nothing. I then had a local service station check it, and they found nothing. We scraped the frame and cleaned the ground connections, changed out the fuel filter and by this time the truck was still intermittently starting, with no indication of what it was, or why at times it would start.

I started messing with the fuse/relay box checking everything. After messing with it, the truck started. I replaced the fuel pump relay, problem still exists. Next day I pulled the fuel pump relay, plugged it back in, and it started. I drove it for a while, parked it. Next morning it wouldn't start again.......

 

Any ideas what it might be?

 

I thought maybe next things to buy/look at, pressure regulator( saw 50-55 psi ) or maybe distributor?

 

I would appreciate any ideas, thanks....

[scooby5121]

Not quite sure but the older model distributor has an electronic modual that would do what you mention.

In the Ford's it was famous. Located under the Distributor cap on the base.

 

Its been a while.

Scooby

[Doug_Scott]

You need to step back and take a logical step by step approach. Tossing parts at it rarely works. You need three things for an engine to run. Do you have those three things? Since the truck does run, you can be fairly certain you have compression. Compression is the one component that is not variable. It is either there, or not.

Do you have spark? Spark can be something that is not always there. Too many components involved to start just throwing parts. Check for spark, then test the module, coil, pick up coil, plugs, cap, rotor, wires etc. Test does not mean replace.

Fuel is the easiest to test. Is there fuel pressure when cranking engine over? Are the injectors working?

Intermittent no start in your description is also very vague. Does it crank over, but not fire? Does it not crank over? Does it matter if engine hot or cold? Raining?

[oldgeeezer]

The truck cranks just fine, intermittently doesn't fire. There was 50-55 psi on the fuel when cranked. It was getting spark. No codes.