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Intermittent Electric Fuel Pump

N

Nick Leonard

Member
I have had an on-going issue with the standard electric fuel pump with 500 hours on it. The symptoms are that it won't always run when the engine is cold. This occurs only in about 1 in 15 starts and it always seems to operate while the engine is running (verified by increased fuel pressure). I don't recall having the problem when the engine was warm but I can't say absolutely. Outside air temperature doesn't seem to be relevant. The problem does not seem to be getting worse.

I have checked the wiring for a poor connection but nothing obvious. I have pulled the pump and bench tested it without getting it to fail. Is replacing the $500 pump the best option at this point?

Anyone else had this problem?
 
If you make the assumption the pump works, then look elsewhere. Some thoughts:
- Verify the terminals tight on the pump breaker and/or pump control switch.
- If you are using a switch breaker, swap it out with a new one.
- If you are using a switch and a breaker, swap each one out separately.
- Verify the pump ground is sound.

Carl
 
Just a thought.

Nick Leonard said:
I have had an on-going issue with the standard electric fuel pump with 500 hours on it. The symptoms are that it won't always run when the engine is cold. This occurs only in about 1 in 15 starts and it always seems to operate while the engine is running (verified by increased fuel pressure). I don't recall having the problem when the engine was warm but I can't say absolutely. Outside air temperature doesn't seem to be relevant. The problem does not seem to be getting worse.

I have checked the wiring for a poor connection but nothing obvious. I have pulled the pump and bench tested it without getting it to fail. Is replacing the $500 pump the best option at this point?

Anyone else had this problem?
Click to expand...

Nick, you have surmised the issue is either the power or the pump. I know it is a pain to get to it, but you might take a sheathed pair of wires and connect to the pump posts and run to either a volt meter or a small light bulb. Then when the failure occurs, you can tell if it is the power or pump. It would save trying the dozens of connections, and components upstream. It would be a positive and definite indicator if it is the pump. Tracking the electrical could come if there were no power.

I hate replacing parts in hopes they were bad then waiting for the intermittent results to occur again. Trying, hoping, and waiting is for fishing, not repairing airplanes. ;)
 
BillL said:
...you might take a sheathed pair of wires and connect to the pump posts and run to either a volt meter or a small light bulb. Then when the failure occurs, you can tell if it is the power or pump.
Click to expand...

That Bill, he smart guy!
 
BillL said:
Nick, you have surmised the issue is either the power or the pump. I know it is a pain to get to it, but you might take a sheathed pair of wires and connect to the pump posts and run to either a volt meter or a small light bulb. Then when the failure occurs, you can tell if it is the power or pump. It would save trying the dozens of connections, and components upstream. It would be a positive and definite indicator if it is the pump. Tracking the electrical could come if there were no power.

I hate replacing parts in hopes they were bad then waiting for the intermittent results to occur again. Trying, hoping, and waiting is for fishing, not repairing airplanes. ;)
Click to expand...

Bill, You're right. I need to narrow it down somehow. Thanks for a great suggestion, even though it will be a pain in the butt to get into the tunnel twice.

Just curious as to whether I'm the only one that has had to chase this kind of problem recently. I recall all the old discussion about the pumps leaking grease into the contacts. Has that issue been resolved?
 
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