Electrical issues Help PLEASE

[Gadget_guy_1984]

I have an 87 S10 pickup with a 2.8R throttle body. I thought I had it diagnosed down to a fuel pump. Friday I was driving and it just shut off. I still have spark, jumped the fuel pump relay and nothing spray gas in the throttle body and it starts. So I put a new fuel pump in, but apparently I have an electrical nightmare on my hands. EVEN WITHOUT THE KEY EVEN IN THE IGNITION the ECM-B fuse blows. According to the scimatics a shop gave me; on that fuse is, Fuel Pump, Fuel Pump Relay, Oil Pressure Switch and the ECM. Except for the ECM have unplugged all of those and traced every wire that I physically could. All the wires look to be in good shape, nothing is brittle, cracked, chaffed or otherwise damaged. can someone please help me.

Thanks
Eric

[lt1s10onair]

its hard to pinpoint without seeing, but ur first step would be to start unplugging items on that circuit (one by one), and after each one is unplugged, check if it still blows the fuse..... when u unplug the faulty part of the circuit, the fuse wont blow out..... theres a starting point at least..... goodluck, and if you need schematics or whatver, pm me, i run a shop and have access to whatever

[Gadget_guy_1984]

I already unplugged one by one and with all of them unplugged it still blows I do have schematics that a local shop gave me I believe that since the truck was running PERFECT almost too good right before it shut off it almost has to be in the computer.

Quote: Originally Posted by lt1s10onair

its hard to pinpoint without seeing, but ur first step would be to start unplugging items on that circuit (one by one), and after each one is unplugged, check if it still blows the fuse..... when u unplug the faulty part of the circuit, the fuse wont blow out..... theres a starting point at least..... goodluck, and if you need schematics or whatver, pm me, i run a shop and have access to whatever

[MadMikeZ28]

Quote: Originally Posted by Gadget_guy_1984

I already unplugged one by one and with all of them unplugged it still blows I do have schematics that a local shop gave me I believe that since the truck was running PERFECT almost too good right before it shut off it almost has to be in the computer.

It must be a short in a wire some where if you had them all unplugged. Check for continuity to ground on each.

[DarkKnite2009]

do you have any buddy's that live near buy with the same truck that you might be able to use there ECM. if you unplugged everything but the ECM then that would be the first thing you should probably rule out.

[Gadget_guy_1984]

Quote: Originally Posted by MadMikeZ28

It must be a short in a wire some where if you had them all unplugged. Check for continuity to ground on each.

Done that
and checked resistance

[Gadget_guy_1984]

Quote: Originally Posted by DarkKnite2009

do you have any buddy's that live near buy with the same truck that you might be able to use there ECM. if you unplugged everything but the ECM then that would be the first thing you should probably rule out.

will one from a blazer work?

[MadMikeZ28]

One from a blazer should work as long as it of the same powertrain. But if you had it unplugged and the fuse still blew then it would be something else.

[hyenad]

There is a wire that goes from your firewall to your starter. That wire has been burned through because it touched the manifold. check that wire. it happened to me a year ago

[Gadget_guy_1984]

I haven't had the time to pull the computer to unplugged it to check

Quote: Originally Posted by MadMikeZ28

One from a blazer should work as long as it of the same powertrain. But if you had it unplugged and the fuse still blew then it would be something else.

[Gadget_guy_1984]

Like I said before the truck was running perfect without ANY problems of any kind and than out of nowhere it just shutoff and the only circuit I have problems with is that one circuit.

Quote: Originally Posted by hyenad

There is a wire that goes from your firewall to your starter. That wire has been burned through because it touched the manifold. check that wire. it happened to me a year ago

[Gadget_guy_1984]

I unplugged the computer and now it isn't blowing fuses. I just didn't have time to do that yet; I work weird hours. The good news is I work for Advance Auto Parts and the new compute will only be about $80

[neo71665]

Quote: Originally Posted by Gadget_guy_1984

will one from a blazer work?

If you test it with another computer it must be one from a 1987 truck/suv. 86/87 two years are the start of the computer controlled crap and GM had the ECM only for one year on the 2 model years. Other computers can work but the pin out on the connector must be changed

[Web-Foot Freak]

I had the same problem not too long ago... Was on my way to work, turned a corner, and my truck just shut off... I blew 4 fuses unplugging stuff, and then it started working all of a sudden again... never had an issue again...