98 Yukon ECM fuse blew

[redchevy914x4]

Any help is greatly appreciated. Yesterday I was roughly 8 miles down a wash boarded dirt road outside town. Not too rough of road but rougher than pavement. Made it to our destination but right when we went to head back to the main road, my Yukon died and would not fire. It was cranking but not starting. checked for spark and had it. checked for fuel and it seemed weak out of the pressure port when I pushed on the shrader valve. Figured it was the fuel pump. changed the fuel filter in the dirt with no result. Got it towed back to town where I have been looking at it today. No CEL on, but would crank but not fire. checked all fuse and found the ECM-B 20a fuse blown under the hood. Replaced it and it fired right up. Has anyone seen this before? Could this have been caused by the bumpy road? Could it be a sign the fuel pump is getting weak or it got hot?

 

[Breakdown]

sounds more like you have a loose wire somewhere, or a wire bumped up against the exhaust and shorted out for a few seconds...

 

[redchevy914x4]

I haven't got a chance to drive it but I am going to start driving it again today. I am going to carry some extra 20a fuses just in case the fuse blows again. I am also going to check my fuel pressure to see where it is at.

 

[redchevy914x4]

well the Yukon has been parked not running for 2 weeks. I have not had time to look at it but every time I try to crank it to start it, the ECM-B fuse blows. After research, I think it is the fuel pump because that fuse is for the fuel system circuit. The fuel gauge also reads way past full. When I get some free time, I am going to drop the tank and disconnect the fuel pump/fuel pump harness and try to start it, if it doesn't blow the fuse, it is either the harness or the pump which will be replaced at the same time. If it does blow the fuse, I have a bigger issue.

Today I was messing around with it and I can pull the fuel pump relay and try to start it with the ECM-B fuse installed and it does not blow the fuse. I can also just barely put the fuse in without the relay installed and I hear a clicking noise that sounds like its coming from the top of the engine somewhere. Anyone have any ideas?

 

[redchevy914x4]

update - found out the oil pressure sensor/sender is on the same circuit. so is the VCM and the fuel pump. I unplugged the oil pressure sensor and it starts. My assumption is the sensor is faulty and needs to be replaced. Anyone have any input? If so please let me know and thanks in advance.

 

[redchevy914x4]

Replaced the oil sender yesterday. still blows the ecm-b fuse when I try to start it. Can unplug the sensor and it will not blow the fuse. Now the trick is to get the timing set good enough so it will start so I can get it to a shop with a scanner to set it correctly. Once it starts and runs, I think I am just going to take this to a shop. I have spent to much time on it so far and need it running so I can drive it.

 

[Black_cirrus]

I would bet money on a fuel pump issue, I fact I should take a pic of the fuel pump connector take out today and it went just like yours. Pop fuse, oil pressure switch was good for a week. Then popped fuse, recheck wiring, then pull the pump and the fuel pump wires were shorting together at the pump.

 

[redchevy914x4]

I can hear the fuel pump running constantly when the key is on with the oil sender unplugged and the fuse does not blow. Would it be running even if it was the issue? with the oil sender unplugged, of course the oil pressure does not read but the fuel reads correctly. With it plugged in, the fuel level reads way over full.

 

[Black_cirrus]

Maxed out fuel gauge is usually an open in the circuit, fyi. It sucks that you have to drop the tank to check. This is the fuel pump connector found on the s10 mentioned above.

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[redchevy914x4]

Looks like that may be the issue. I am going to look at it a little this afternoon after work to see whats going on. Does the fuel pump and the oil sender run off the same wiring? It is weird that it will start and run with the oil sender unplugged.