Electric fuel boost pump

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noahfong

Pre-takeoff checklist
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Aug 20, 2013
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Noah
I had a belly drain fuel leak repaired which required the fuel tanks to be drained as there is no shut off between the tanks and the belly drains, where the leak was. After the repair, I found the electric boost pump sounding hushed and not providing a boost in pressure. This is odd to me because I bought the pump new (Aero Performance 4140-00-17CJ) in May of 2022 (just last year). The airplane has only flown around 25 hours since then. (I fly it at least every two weeks - just not very long). I only use the pump to prime the engine. It worked fine when I brought the airplane to the shop back in July. Just picked it up earlier this week on Monday.

The only thing I could think of is that the pump was dry for almost 2 months (maybe).

What is the likelihood of this failing the pump?

Or, is it just a coincidence?

Does anywhere re-furbish these pumps?

Thanks!
 
aeromotorsllc.com is the goto place to get fuel pumps overhauled.
 
Those pumps do not like being run dry, and are damaged by doing so (there is a BIG sticker on the pump stating that). Perhaps someone ran it dry and damaged the vanes. Your pump was made by CJ aviation (that's why it has the CJ suffix) http://cjaviation.com/ I've had really good luck with them in the past. If the pump really is bad and it's not some sort of electrical issue (supply wise), and it wasn't run dry, that pump should still be under warranty.
 
Bell206 said:
What aircraft? Did they use the pump to drain the fuel tanks?
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I just went to the shop and asked. The mechanic said absolutely not. He is aware that these pumps are not meant to be on continuously and that would severely limit their life. He is baffled himself.
 
Ryan Klems said:
Those pumps do not like being run dry, and are damaged by doing so (there is a BIG sticker on the pump stating that). Perhaps someone ran it dry and damaged the vanes. Your pump was made by CJ aviation (that's why it has the CJ suffix) http://cjaviation.com/ I've had really good luck with them in the past. If the pump really is bad and it's not some sort of electrical issue (supply wise), and it wasn't run dry, that pump should still be under warranty.
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Yes...you are most correct on all counts. I called the CJ number on the pump and they said they are MacFarlane, now. I told the girl all the shop told me and my experience with it and that I bought it new in May 2022. She said she will inquire as to the policy and get back to me. So, I'm keeping my fingers crossed.

Thanks.
 
Make sure that the pump isn't dead because of some electrical supply issue. Too often the mechanic pulls the wire off the pump and finds 12 volts there and thinks the system is OK. But the meter can see 12 volts even when there's a bad switch or breaker or connector somewhere, because it only takes a few microamps to satisfy the meter, but several amps to run the pump. Ohm's Law tells us that a large resistance will not drop the voltage much for a small current, but will cause a big drop for a large current.

The voltage needs to be checked at the pump while it is still connected and switched on. That will tell you whether the pump or something else is busted. Overhauling a perfectly good pump is a great way to get rid of money.
 
noahfong said:
He is baffled himself.
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Without knowing the aircraft type cant offer much more. However, its quite possible with the defuel and subsequent work some old or new trash in the tank may have partially clogged a pump filter or port? Maybe perform a flow test for the pump output and see what you have.
 
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