Electric Fuel Boost Pump for M20K Issue...

[MooneyShine252]

I have a M20K (25-1187) and had the electric fuel boost pump overhauled within the last two months.  I sent it in for overhaul because it was leaking a little fuel, and during descents I could smell fuel in the cockpit...it got more prevalent with the landing gear in the down position.  My A&P found evidence of the pump leaking fuel.  Although it was a small amount of fuel it was time to send it out...it was the original pump that has never been overhauled according to the engine logbooks. Before I sent it for overhaul, all of my fuel boost switches worked fine (Low Boost, High Boost, and Prime switch).  After I got it back from overhaul and installed the pump, all Fuel switches work except for the Low Boost Switch??? All three Boost Pump Switches (LOW, HIGH and PRIME use the same electric fuel pump I had overhauled) I'm looking for help to resolve this issue.  Any thoughts on this would be more than welcomed!!! Thank you.

[Z W]

I would check the wiring at the pump that was removed.  Sounds like the wire running to the low boost pump switch may not have been reinstalled correctly.

[Fly Boomer]

12 hours ago, MooneyShine252 said:

Any thoughts on this would be more than welcomed!!!

Z W has the answer.  "Low Boost" is just circuitry to run the one-and-only pump at a reduced voltage.  The wiring for that reduced voltage circuit has been disturbed.  If the pump runs on high, the pump is fine.  The SMM makes it clear that if the pump is changed, the low boost voltage should be adjusted to provide 8 PSI or less.

 

[MooneyShine252]

Thank you for the information, this will be very helpful. I appreciate it greatly!