6V Fuel Pump issue

[crelledge]

Hi guys! Thanks again for all the help with the accelerator linkage a while back, I think we’ve got something approaching workable going on that front!

Well, after a rebuild of the mechanical fuel pump, it started vibrating really strongly and visibly when the car was running and eventually broke off at the flange on the engine. Still not sure what that was all about, whether it was seated incorrectly on the cam or the rubber diaphragm was too stiff or what, but in the meantime we’ve decided to run a little 6V fuel pump instead, similar to one of those little canister-shaped AirTex models.

Problem is, when we hook it up near the tank and turn on the switch, the pump jumps once, then sits and does nothing but get hot. Turn it off and on, and it will jump again, then stay still. You can actually see the fuel moving in the clear plastic fuel filter we have, but only when it first gets power, then nothing.

So I took it off and made a bench set up consisting of: Lawnmower gas tank > pump > catch can. I primed the pump, and same deal: the pump will move gas, but only when it first comes on. So if I take the ground and put it on a battery on the bench and take the tan wire and stick it on and remove it, stick it on and remove it, etc. from the positive battery post... it will move fuel.

So what’s the deal? This is the second pump we’ve gotten from the manufacturer, thinking the first one may be defective, but no dice. I also thought maybe it wasn’t working because of the length of wire required to get all the way from the battery to the fuel tank where we put the pump made resistance too high, but the bench test disproved that.

Any advice?

[Russ T. Fender]

I used to run an electric fuel pump and it would click once which was an indication that it reached pressure.  Once that occurred it would no longer click until fuel was consumed and the pressure needed to be restored.  I can't say for sure that what you are experiencing is the normal function of an electric fuel pump but in any event the pump will stop once the pressure it is set for is achieved.  When you start the car does it run out of gas or does it keep running?  If the latter, the pump is probably fine but it should not be getting very hot, for obvious reasons.

[chetbrz]

I am not familiar with the type of pump you are using  but could 6v polarity have anything to do with the problem.   The car is positive ground.

My 2 cents.

[crelledge]

Well it seems the manufacturer we were getting from was just no good- got a 6V fuel pump off the shelf from our local vintage parts store and it works like a charm. Go figure!

[chetbrz]

Great,

Nothing worst than having to troubleshoot new parts that don't work.   

[Articifer Tom]

May want to go over your mechanical pump and make sure it has correct arm on it . Many were rebuild and some after market companies bought old stock and refurbed for newer motors . Also any chance you got it on wrong side of cam ? 

[crelledge]

It's possible that's what happened, that it got on the wrong side of the cam- unfortunately now the pump cracked at both bolt holes on the flange so it's totally unusable now, probably couldn't even use it as a core. Ah well, live and learn. At least I got a working electric one now!

[Articifer Tom]

I have a couple extra pumps . If you get me a pic and the three part number top , bottom and arm . i check my stock .