Ecmb Fuse

[outdorcrazy]

I have a 1990 GMC Jimmy and the fuel pump and ECM have been changed.
But the ECMB 10amp fuse keeps blowing as soon as the key is turned on.
Any ideas?

 

[colbystephens]

I am having this problem on my '90 K5 as well, though intermittently. One thing that has been suggested to me is the oil pressure switch. I haven't changed mine out yet, though I have one in a box on the shelf. But, since my problem is intermittent, it makes it much harder to find.

So, check that and see what you come up with. If I recall right, it's under the distributor on the driver's side on the back of the engine.

 

[dyeager535]

Are the injectors on the ECMB fuse?

If they are, I would check the wires where they tend to get pinched (and brittle) at the air cleaner.

I can't say that components don't cause shorts, but more often than not it's the wiring itself. If the problem is consistent, it is very easy to find. You get a diagram of all circuits on that fuse, and use a multimeter set to continuity to find your 12V wire that is shorted to ground.

 

[snowdriver]

had this same problem wiyh my 1990 blazer,turned out to be a pinched wire back behind the distributer,on top of the bell housing,close to the firewall that was shorting out,hell of a spot,but repaired the wire,added some protective sheathing to it,problem solved

 

[Russell]

Are the injectors on the ECMB fuse?

If they are, I would check the wires where they tend to get pinched (and brittle) at the air cleaner.

I can't say that components don't cause shorts, but more often than not it's the wiring itself. If the problem is consistent, it is very easy to find. You get a diagram of all circuits on that fuse, and use a multimeter set to continuity to find your 12V wire that is shorted to ground.

Nope, ECMB = hot at all times for the ECM and feeds both the fuel pump relay and the oil pressure switch. 90% of the time it is an issue with the wiring to the pressure switch.

 

[1970worthog]

I know its not a K5 but just had this problem in my 91 s10.
Traced it down to an injector wire that was grounding out on the air cleaner housing. Changed the fuel pump relays while I was at it and havent had any problems so far.
Was about to change out the oil pressure switch but didnt need to go that far.