1988 Crew Cab Dually ECM B Problem.

[Novadiecast]

Hello all. I am new to the forum and need your help.

I have an 1988 C30 454 FI Auto trans that has a problem. It will not start. The ECM B fuse blows as soon as you touch a fuse to the fuse block.

What I have checked so far.

Disconnected computer behind glove box. still blows fuse.
Disconnected injectors. Still Blows fuse.

What could cause this??? Thanks in advance for any and all help.

[Novadiecast]

I also unpluged the fuel pump relay. Still Blows the fuse!!!

[Captkaos]

If you apply voltage to the test lead going to the pump does it come on?  This will bypass the ECM/relay.

[Novadiecast]

Do you mean the test lead at the relay??? It does have dual tanks.

[Captkaos]

yes the one at the relay. 
Is the switch operating properly?

[Novadiecast]

OK, when I power the test lead at the relay I does not run. In fact when I touch that wire to the battery it gives a little spark like there is an immediate draw.

 If I pour gas down the throttle body it fires right off a run perfect till that gas is gone.

[Novadiecast]

Maybe I should say what led up to all of this. I was driving down the road and it died at a left hand turn. I never made the turn. Just before this happened about 5 miles before, the check engine light came on and then went out. Then it died in the highway waiting to turn. Gas in both tanks etc. It just died. Was running great before this. Now my truck has been dead for almost two weeks.

[VileZambonie]

Is this truck a C30 (new body style) or an R30 (73-87 body style)?

Unplug the oil pressure switch and see if it still blows.

[Novadiecast]

Its an R old style-the only ones with style.

I will try the oil pressure switch in the morning.

[Novadiecast]

OK it was not the oil pressure switch.

It was the power wire to the coil. It was fraid by the distributor clamp. repaired the wire and TADA!!!!

No more problems, runs like a top and no blown fuse anymore.

Thank you 73-87chevytrucks.com

[Captkaos]

Excellent.  I am envious that was a pretty simple fix.

[Novadiecast]

Yes and I am glad I did not want to get into a computer thing problem or tracking down miles of wires. My old 78 was way more simpler than this one but I still like it .