What does it mean when the fuel pump impeller feels 'magnetized"?

[lelandEOD]

I have begun the process of trying to start my newly purchased M109. First problem: the fuel pump was getting 25v but wasn't turning. We discovered a burned fuse so I replaced it. = zap; immediately burnt the second fuse.

I pulled the pump assembly (not an easy task with the 109 box in place) and drained 40 gallons of 8 year old diesel fuel from the tank. The screens on the pump were partially clogged so I soaked it in a solvent tank and blew it out with compressed air. Before reassembling it, a buddy told me we should check the impeller for free movement so I tapped out the bottom plate and sure enough, it doesn't spin easily. Oddly enough, it will rotate but feels magnetized. Like, when you turn the impeller, it feels like you are trying to prop-start a rotary aircraft engine. Weird! My only guess is that perhaps voltage was left on while the motor was stuck and that somehow created a magnetic field around the armature?

Anyway, I pulled another pump off a parts truck and found a good running pump motor so I should be GTG there.

Since there was a lot of crud in the bottom of the tank, I opted to pull it and am going to have a radiator shop boil it and epoxy line it for good measure.

More to come!

 

[m16ty]

I suspect a bad motor or a short in the wiring.

The impeller is supposed to be magnetized. That's how it works. There is no hard connection between the motor and impeller, it is driven by magnetic force. I would assume it is this way to keep fuel out of the motor and not have to worry about a shaft seal going bad.

 

[Tracer]

Smart to remove the fuel tank and have it cleaned. Keep us posted, I would like to see how your fuel tank turns out.

 

[Jeepsinker]

The way that impeller feels is fine. They should feel that way. Since you cleaned the screens and all out, plug it in and see if it runs now. Sometimes the crud just jams them up.