Electric fuel pump internally shorted

[thompsonbr87]

All packed up for Oshkosh and ready to go. Aaaaand electric boost pump appears to be shot. Power lead is shorted to ground. Besides discovering that the boost pump circuit is not protected (will be remedied), I need a new boost pump. This is new territory for me. Is it as simple as finding something that is 14V, ~30psi, and up to 15gph? What sort of options do I have? Is it possible (economical/feasible) to just replace the motor? Looks like this company might do that?

Weldon 8850-5
IO-320-C1A

[10builder]

Originally Posted by thompsonbr87

All packed up for Oshkosh and ready to go. Aaaaand electric boost pump appears to be shot. Power lead is shorted to ground. Besides discovering that the boost pump circuit is not protected (will be remedied), I need a new boost pump. This is new territory for me. Is it as simple as finding something that is 14V, ~30psi, and up to 15gph? What sort of options do I have?

Can you provide a few more details on your installation? Possibly someone @ MQY may have a spare and we could reach out to EAA162.

[Hartstoc]

I strongly recommend that you read through this three part series of VAF threads. The link below is to part 3, which will provide you with a lead to a pump that will fit your needs perfectly and draw a fraction of the current that most pumps do. It has served well up to 230HP with fuel injection. -Otis

http://www.vansairforce.com/communit...d.php?t=168793

Links to parts 1 and 2 are included at the bottom of the post this will take you to.

[thompsonbr87]

Originally Posted by Hartstoc

I strongly recommend that you read through this three part series of VAF threads. The link below is to part 3, which will provide you with a lead to a pump that will fit your needs perfectly and draw a fraction of the current that most pumps do. It has served well up to 230HP with fuel injection. -Otis

http://www.vansairforce.com/communit...d.php?t=168793

Links to parts 1 and 2 are included at the bottom of the post this will take you to.

Perfect! Wasn't really sure where to start learning about these things. Thanks!

Originally Posted by 10builder

Can you provide a few more details on your installation? What type of pump?

Weldon pump. It's marked 8850-5, but it looks like that may just the p/n for the electric motor portion of the assembly. Although that may be all that I need...

[skylor]

Originally Posted by thompsonbr87

Perfect! Wasn't really sure where to start learning about these things. Thanks!



Weldon pump. It's marked 8850-5, but it looks like that may just the p/n for the electric motor portion of the assembly. Although that may be all that I need...

You can purchase replacement motors for Weldon pumps:

https://www.aircraftspruce.com/catal...ldon-motor.php

Are you sure it's actually shorted internally and isn't stuck from FOD or internal impeller failure?

Skylor

[thompsonbr87]

Originally Posted by skylor

You can purchase replacement motors for Weldon pumps:

https://www.aircraftspruce.com/catal...ldon-motor.php

Are you sure it's actually shorted internally and isn't stuck from FOD or internal impeller failure?

Skylor

Pretty sure. Power lead to ground shows no resistance.

[flyinga]

Basic question; if the power lead is shorted to ground how do you know pump is shot?

[thompsonbr87]

The pump itself may be fine. I think it's just the motor. That was just my initial reaction to flipping the switch and not getting any (desirable) reaction.

[thompsonbr87]

Originally Posted by thompsonbr87

The pump itself may be fine. I think it's just the motor.

Glad to report that this was indeed the case. I talked with several people at Oshkosh, including Charlie Duffie with CJ Aviation who helped clear up my understanding of electric motors and also encouraged me to pull the motor off the pump and check a few things on it myself rather than sell me a whole new assembly. I spent a little more time after getting home learning about electric DC motors. I remembered a bit of the theory about electricity and magnetic fields from school but had never really used that in any practical application. It was surprisingly simple, really. Cleaned up the commutator, reassembled the motor, and voila! Yet again, I'm discovering that the wizard behind the curtain isn't quite as intimidating as I had once thought. Giving that little tag in my signature some exercise!