ECM B fuse blowing

[yeager1]

I keep blowing my ECM-b fuse in my 87 K-30 (350 TBI) and I am not sure why. I know that the fuel pump is on that fuse but I don't think the pump is the problem, but the wiring could be. What else is on that fuse? I have a manual, but it's not a factory one and the wiring diagrams are not very good. Any thoughts as to what wires/components are on the ECM B fuse? Does anybody know where I can download a good wiring diagram?

 

[k20]

I had that problem when I had a fuel pump lockup, thats all I can tell you.

 

[southernspeed]

This has been covered a lot recently. It would be worth doing a search.

 

[k5floyd]

try unplugging the connector to the fuel pump and then turning the key to run with it unconnected. itll be on the inside of the drivers side frame rail near the tank. if the fuse doesnt blow, try replacing the fuel pump relay, like 8$. the relay should be on the passenger side of the firewall at the top. also, look for any pinched and/or bare wires going to the fuel pump, relay, injectors, etc.

 

[K5MONSTERCHEV]

What gets power through the B fuse?

 

[dirtwarrior17]

check all your sensor wires especially the cps ( cranshaft position sensor). I blew my ecm b fuse when i did a swap... i was extending the wires to fit the 355 and touched the two bare cps wires that i was extending together, they sparked and it blew. If you have exposed wires anywhere on that circuit the fuse can blow.

 

[yeager1]

Thanks for the info! I'll give it a try and get back to you.

 

[yeager1]

I checked the wiring to the fuel pump and it looked marginal, so I replaced the wiring all the way from the tank to the fuse block (there was no relay- goes directly from tank to fuse panel. The pump works and runs fine, but the ECM B fuse still blows- I guess the fuel pump is on a different fuse.
Anyway- The ecm b (10a) fuse still blows and the truck won't start- I disconnected all the wiring to the coil and distributor and the fuse still blew. Tommorrow I am going to pull all the wiring out of the harness and check wire by wire for any shorts. Any other suggestions? Without a decent wiring diagram I am kind of at a loss.

 

[dirtwarrior17]

Might be a good idea to pick up a manual with the vacuum/wiring diagrams. I can't think of any other reason that fuse would blow besides a bad circuit meaning shouted wires somewhere on the fuse circuit. I am positive the pump is on the ecm b fuse. All i can tell you .... good luck

 

[yeild2me]

Try un plugging the ECM and seeing if it still blows.... If it doesnt, bad computer, if it still does, bad wiring. I hooked my battery up wrong and fried my ecm and it was doing the same things as you are saying.

Hope this Helps.ROB

 

[yeager1]

The ECM was bad- replaced it and it started right up. Thanks for the info.