I have been trying to figure out why I keep blowing the ECMB fuse on my sons 1990 G20 van. It blows as soon as it is replaced. I checked all wires for shorts. I can't find any. I replaced the fuel pump, fuel filter and fuel pump relay. The fuel pump does run when the key is on. I tried pulling the connectors off of the FP relay and the oil pressure switch. Still blows. Pulled connectors off of other sensors. Still blows. Removed the connectors from the computer. Fuse doesn't blow. The computer was just laying along side the drivers seat. Could a bad computer blow theECMB fuse? Or is it just a problem within the fuel pump circuit?The vans wires for the towing lights are pretty messed up by the hitch. I didn't think this would effect that circuit. Please help.

 

Im having the same problem in a 1989 K30 pickup. Im stumped also !

 

i've seen a few times where the orange wire goin to the oil pressure sender is shorted out against the doghouse on Gvans. try checking that wire.