1996 k1500 5.7l 150000 miles ecm1 fuse blows

[Tiny Tony]

The ecm1 fuse blows randomly. No stored codes. The backstory is I replaced intake gaskets, cap & rotor, spider injector. I've been running it for a month and it runs great. the other morning I start to go to work and a couple blocks from the house the truck shuts off like turning the key off. I had the wife come and we pulled it home. The next weekend I hooked up my fuel pressure gauge and no pressure. I hooked up the scanner and no com. looked at the fuse box and ecm1 fuse popped. Put a good fuse in started right up. Checked diagrams, crank sensor, fuel injectors, coil, and ign module are on the circuit. With a good fuse in and key on went around and wiggled all the wires looking for a short to ground. no short found. Started it up and idled for an hour and drove around the neighborhood for an hour. Ran fine. Next morning go to work ran great no issues. I start work at 8 and at 1030 I go out crank it and it coughed and cranked no start ECM1 Fuse blown. I wired up a 12v lamp in the fuse slot turn on the key and the light is on. start moving wires wires and found nothing. wiggled the large injector connector light shut off, and it sounded like the fuel pump primed. took the large injector connector apart and can't find a short to ground. My question is can the amazon bought spider injector short to ground?

 

[Silverado1994]

Hang tight. Got a couple of schematics......

 

[Tiny Tony]

If memory serves me correctly the fuel pump is on that circuit.

no fuel pump on that circuit

 

[Silverado1994]

no fuel pump on that circuit

You're right. I was in the middle of editing that so I didn't stick my foot in my mouth. Too late. Looking now....

 

[stutaeng]

You have either have a short in the wiring harness or something is drawing a load larger than what the fuse is rated for.

This is one of those problems that is going to be a real challenge to find. What else is on that circuit? Can you post diagram? How's the rust on your truck? If it's crusty, I'd probably just peel the loom on the harness and take a look at the wiring integrity one by one.

Edit: Since you seem to suspect injectors as potential culprit, check the resistance of each. On the later trucks the injectors check out around 12k ohms? I'm sure you can find specs for the spiders.

 

[Silverado1994]

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[Silverado1994]

Could be an internal short in the on the spider side connector. I've also seen bad connections at spade terminals do the same thing with excess resistance but that's a long shot.

 

[Tiny Tony]

You have either have a short in the wiring harness or something is drawing a load larger than what the fuse is rated for.

This is one of those problems that is going to be a real challenge to find. What else is on that circuit? Can you post diagram? How's the rust on your truck? If it's crusty, I'd probably just peel the loom on the harness and take a look at the wiring integrity one by one.

Edit: Since you seem to suspect injectors as potential culprit, check the resistance of each. On the later trucks the injectors check out around 12k ohms? I'm sure you can find specs for the spiders.

Yup she is a crusty one I have started to do just that.

You have either have a short in the wiring harness or something is drawing a load larger than what the fuse is rated for.

This is one of those problems that is going to be a real challenge to find. What else is on that circuit? Can you post diagram? How's the rust on your truck? If it's crusty, I'd probably just peel the loom on the harness and take a look at the wiring integrity one by one.

Edit: Since you seem to suspect injectors as potential culprit, check the resistance of each. On the later trucks the injectors check out around 12k ohms? I'm sure you can find specs for the spiders.

I will check the injectors one at a time. Thanks

 

[Tiny Tony]

You must be registered for see images attach

yup thats her

 

[stutaeng]

I was going to say,... there's a lot of pink wires that have potential to ground out...

At least you didn't run out and change your fuel pump! I'm joking!