ECM 1 Fuse keeps blowing

[John Moore]

Hey guys,

For the first time in 5 years of owning my Tahoe, it has finally left me stranded! The ECM 1 fuse instantly pops every time I turn the ignition on... I was hoping for a wire on an exhaust manifold grounded out...sadly, that was not the case. I unplugged the computer and it still popped the fuse...I unplugged a few sensors on that circuit and it still popped the fuse...

Last, I unplugged the main injector harness directly on top of the engine...the fuse would not blow with that harness unplugged. Is my injector assembly bad...? I replaced it a few years ago with the upgraded Delphi MFI version...

It's weird, I drove it to a friends house...it sat for about an hour, then it wouldn't start when I tried leaving.

Any help is greatly appreciated!

 

[Schurkey]

2000 Tahoe, Vortec 5.7L???

I'd be inspecting that injector harness with an ohmmeter, or a specialized injector tester.

I have never done this, but that main injector harness connector should allow you to test the resistance of each individual injector, along with testing each injector to ground. (They do fire the injectors sequentially--not batch-fire...right?) I expect you'll find a failed injector, or the harness has abraded insulation so the conductor inside is grounding to some engine part.

Worst case--remove intake manifold so you can visually inspect harness for cuts/abrasions; and unplug each injector to perform a resistance check. If you have the specialized tools, you should be able to fire each injector using the tool; combined with a fuel pressure gauge you'd know which injector(s) are still working, and which aren't.

 

[mrksc83]

If you remove your injectors i believe you can check the solenoid operation with a 9v battery, you can also run wires with aligator clips staight off the battery to the injector