I have a Wren 75 that has been out of service for about a year. Installed it in another plane recently and went to start it but the fuel pump will not pump fuel. When tested with prime on, voltage goes to the motor and it does get warm, but no fuel is pumped. I think the fuel may have thickened up inside the gear pump preventing the gears and motor from turning. Anyone have any ideas on how to get this pump working again?


Terry

Disconnect it from the ECU & intermittently connect it (just a stab) with something
like a 4.8 - 6v receiver pack.

Watch it doesn't spit at you!

If it doesn't start to run you may have to put a little jet fuel in a container just
deep enough to submerge the pump itself (not the motor) when stood on it's
end & leave it to soak for a while to try to dissolve the gummy oil.
for a while. Then use the battery again.

Were you using 2 stroke oil? - John.

Once you free it up you could put some tubing on it & run it on, say, 2 volts pumping the fuel
out of a container, through the pump then back to the container in a continuous loop just to
flush the goop out. Then run it from clean fuel to waste for a final flush.

Probably a good idea to check & clean/flush fuel lines & filters too. - John.

Not using 2 stroke oil. Using Mobile turbine oil. I have pushed some fresh kero through it by blowing on the vent line to the fuel tank and bypassing the solenoid. Maybe this will loosen it up enough to turn over. I'll keep trying it for the next few days and see if I can get it to work. I don't want to have to take it apart. I'll try the higher voltage from a receiver pack as you suggest. See what happens.

Terry

Was able to free it up with a 6V receiver battery as you suggested. Worked great. Had to hit it a few times back and forth reversing polarity. Once it freed up, it seems to run smoothly now. Thanks for the tip!

Terry

And there goes another happy RCU customer.

Nice that you got that one resolved within a few hours, I have a pump that went bad, I had it for years but with very little use.

Good news!

Don't forget to thoroughly flush it out to remove any manky
oil that may be in it. If any gets into the fuel tubes in your
engine it will give you grief. - John.