ecm fuse blows, any ideas please...

[schamp]

Just had my emc fuse blow. Actually it was the ecm-b fuse. Put in another 20 amp fuse and suburban started then quit. Fuse blown again. Put in a 30 amp fuse (I know) engine started and made it to the house. Ran pretty well. No DTC or light came on except for when fuse was blown the Wait to Start light did not come on. Any ideas. Stats are 211 thousand miles on suburban. Pump was changed out around 100 thousand. When it quit engine was idling and ac on. Had been sitting about 5 minutes. Engine temp (dash) ok, about 180. Engine bay temp unknown. Suburban has no history of throwing codes. Thanks in advance for any ideas from the support group. schamp,

[schamp]

I should have included that it is a 1997 Suburban 2500 HD. Thanks, schamp

[More Power]

Pull your fuel lift-pump relay, then see if it still draws too much current. The relay is under the hood in the fuse/relay panel.

If it still draws too much current, pull the electrical connector off the oil pressure switch.

If either suggestions above solves the problem, reconnect the relay and oil pressure switch connector, then disconnect the fuel-lift pump electrical connector, and try it again.

My guess is one of the above is causing the problem (either a bad relay, oil pressure switch or lift pump).

Because the engine ran with a 30 amp fuse, I doubt you have a computer problem. The ECM-B fuse powers the lift pump circuit in both start and run mode, in addition to the computer.

MP

[schamp]

Thanks MP, I will do as you suggest. With 211K on the clock it may be just as well to replace both. Then go back to the 20 amp fuse and see what happens. Will let you know. Thanks, schamp

[Uncle Wally]

I had the same thing happen with a 90 gasser. The culprit was a loose connection on the terminal blocks right above the heater/A/C unit under the hood. There's 3 plastic nuts that are easy to take off with yer fingers. Pull the plastic off and there are 5 or 6 14mm nuts that distribute power for the truck.

Waldo