MFI Fuel pump - bench test & trouble shoot - what am I missing?

[911kiwi]

Hi,
Hoping Mark Jung or others experienced in this can help me out here.
Dismantled my 001 fuel pump that stopped working to discover a wire required resoldering - phew that was easy, I thought! NOT!
The pump is a rebuild from Pacific Injection, only 5 years. All the windings and brushes look like new. There is continuity between the +ve and -ve terminals.
When I connect them to 12v, nothing. What am I missing? Or is there something else I could be checking.
I assume that spinning the motor for a couple of seconds without fuel surrounding it will have no detrimental effect.
Look forward to any advice that may help me solve the puzzle,
Cheers
Gary

[2.5MFI]

What wire needed the resolder in side? If you have an ohm meter, check to see what the impedance is. Should be 1.3 to 1.5 Ohms across the + & - terminals. When you tested the pump with your 12 volts, was it on the car or on your bench?

[304065]

How many amps is your power source? Try it from the battery. Don't burn anything down.

[911kiwi]

Thanks for the replies. Mark, the loose wire was the coiled copper one which connects on top to one of the brushes. Just checked the impedance - zero! Test performed on bench. 304065, power source was the battery.
Any suggestions?

[911kiwi]

Well, just bench-tested again and it spun this time ... for a 1sec or 2. Then emitted a puff of smoke! :-( I figure that was the reason the wire had become unsoldered in the first place - guessing a short in the winding caused an overheat and melted the solder. So I'm back to square one - but now I know I have a required re-wind as well. Thanks for your help guys - I'll check back when I find out how much rewinding the armature costs.

[2.5MFI]

Sorry to hear, but at least it was on your bench and not on the car when it smoked!

[911kiwi]

Yes, I agree Mark! Plus the hassle of having connected everything up, clamped the pump in, scraped my knuckles, bumped my head, then have to take it all apart again. Thanks again for your help - I'll keep you posted and hopefully report back with better news.

[911kiwi]

OK - I'm back with better news! I guess it pays to be stubborn. Revealed as much of the armature as I could and gave it a thorough clean. Resoldered the wire. Connected it to the battery one last time. Now my pump works
again. Ran it for 4 bursts of 3 secs and no issues. So figure that I should bench-test it with fluids to ensure there are no leaks before putting it back under the car. My concerns are these: since the pump is full of fuel normally and the arcing takes place safely underneath that fuel, should I somehow prime the pump to prevent any air pockets and possible fuel vapour? I thought about test-running it with kerosene first, but eventually I'll have fuel pumping through it when the fuel lines are reconnected. Am I safe or are there some precautions I should be taking. Don't want to be putting a "bomb" under my Porsche, setting my 911 alight, along with the 356 and 912 parked beside it!
I'm itching to get this finished, but cautiously hesitant at the same time.
I won't make a move until I hear back from the experts!

[neilk]

I don't have anything to add, but do you have any pictures you can post of the internals.

Thanks

[911kiwi]

Hi Neil,
I'll take some of the other disassembled pump and post them later in the day.