I need some help with blowing ECM fuse in my 87

[AustinBelair]

I was taking my dad to the cruise-in last night and the truck died while doing 45mph. I swear I heard a noise before it died. A pop, a clank, something. I pulled into the auto parts store parking lot. It will crank but no fire. It's an 87 with the 4.3L V6 TBI and dual tank. I swapped fuel pump relays and same result. I bought the truck a year ago and never tried to use the driver side tank, only the Pass.

I flipped the switch to the Driver side and same result. I poured a gallon of gas in the main tank I've been using. Nothing. I laid under the truck and had my father key the ignition. I didn't HEAR the pump prime but we were on a busy road so I couldn't hear it real well if it did prime. It's like both pumps quit working.

Is there a fuse for the tank selector valve or for the fuel pumps that I am not seeing? I find it odd that both pumps quit UNLESS the drivers side never worked and I didn't know and the pass side died last night. Not sure where to start. Maybe the fuel pump relays on the firewall are dead?

Replaced the pass side tank, pump, tank selector valve, fuel pump relay and still no start.

I just replaced the ignition module in the distributor and the oil pressure switch and it was still not starting. I looked and no fuel at injectors. I noticed when I turn the key on, the pump will not prime but when I kill the key, I can hear the pump run for 2-3 seconds. Still no start. I looked at the fuse box and the ECM fuse is blown. I replaced it and BAM it fires right up and idles beautifully, better than it ever has. Unfortunately, when I turn the ignition off, the ECM fuse blows again. WTH

[AussieinNC]

Change the ECM there is a short to ground issue blowing the fuse....

There is also a bad connector issue corrosion issue with these vehicles...this link shows a V8 Vortec but yours is similar loom and issue...

https://www.youtube.com/watch?v=721A_rKyLIA

[AustinBelair]

Wow, I started tracing wires and BAM! I found the white injector wire was pinched/chaffed under the ring that goes around the top of the throttle body. It was grounding out against the the TB. I re-positioned it, taped it and made sure it was out of the way. Done. Fires right up now

[AustinBelair]

Got both all new tanks/pumps etc installed with new selector valve and dash switch. Pass side works perfectly. Drivers pump will prime but just cranks and will not fire. I've checked everything.

I did find a kill switch from the previous owner. They cut the power wire from the dash switch and installed an on/off toggle to kill both pumps.

I deleted it and tied both wires together to complete the circuit. Still nothing.

If I lay under the truck and have someone key the ignition I don't hear the selector valve switching tanks (not sure if you're supposed to) but the pumps do prime.

Any ideas?

[AustinBelair]

Bump