88 1 ton wiring vs 88 1/2, 3/4 ton

[smdk2500]

So I'm trying to help a buddys stepdad with his 88 chevy 1 ton. The 1 tons where still square bodys. How much difference is there in the wiring for the engine. He is blowing one of the fuses for the ECM. I don't know which one at this time. He just put another engine in it drove it roughly 100 miles and it started acting up. So if anyone has a idea if the engine side of things are the same please let me know.

 

[b454rat]

IIRC they were the same in those years....

 

[PlayingWithTBI]

^^^X2 from 87 - 89 they should have the 1227747 ECM and TBI, I think. IF so, it looks like wire #439 feeds the ECM. These diagrams are from and 88.

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Check your grounds too.

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[smdk2500]

Thank you. Yes it is a TBI. Up untill a few months ago this was the newest truck he has ever owned. Its on the 3rd engine that I know of. He would love to get a newer rig but to do that would need big bucks to do it. Hopefully we can get something figured out this weekend.

 

[someotherguy]

Long shot here but check the injector wiring where it gets close to the TBI spacer ring. It can get brittle and rub against the metal ring and short out. Memory vague here but I believe I've seen others report blowing ECM fuses for this reason.

Richard

 

[smdk2500]

I knew that the injectors ran off one of the ecm fuses. I wish I could get out of him which one it is popping make life a little easier at least i could have a game plan for it.

 

[PlayingWithTBI]

It can get brittle and rub against the metal ring and short out. Memory vague here but I believe I've seen others report blowing ECM fuses for this reason.

That's a good possibility.

Keep in mind when the ECM fires the injectors, it grounds out the negative side, they are fed 12VDC constantly when bulb test, start, and run.

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[PlayingWithTBI]

I knew that the injectors ran off one of the ecm fuses. I wish I could get out of him which one

According to the diagram above, it's a separate fuse feeding the injectors. It'd be nice to know which one is blowing (as you said).

 

[smdk2500]

Well I didn't get a chance to look at it but he said he found a rubbed wire somewhere that was doing it. Again wish I knew what one but guess atleast he got it fixed and can start making money again.