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fuel pump

Posted: Sat Oct 09, 2021 7:37 am
by B@fink
Does anyone know if the pinto mechanical fuel pump should have non return valves in it? I swapped to a shiny new one during the rebuilding as a matter of course because old shrivelled pump diaphragms aren't a wise idea but it seems to bleed the fuel back to the tank now. I don't recall having issues in the before times but the petrol seems to be bleeding back to the tank within very little time and as it stands around for some time I'm having to crank it to get it to come back. Is this new pump just bobbins and needs replacing? Do they not have none return valves and the carb solenoid is the bobbins option? Should I just inline a petcock and that'll stop it draining away? I've tried an aluminium non return valve that is still letting it flow back, but it now hangs around for a week slowly getting to the tank. Thoughts anyone.......

Re: fuel pump

Posted: Sat Oct 09, 2021 2:32 pm
by stevemarl
They all have to have non return valves, that`s how they work. Diaphragm goes up, sucks in, through inlet valve . Diaphragm goes down, inlet valve closes, 2nd, outlet valve allows fuel out. Repeat. Some, like the genuine Ford AC ones have rubber seals around valve which work better: the Pierburg for example uses spring steel plates which work fine at pumping but won`t be so effective at preventing leakage back.
(The carb solenoid is just to cut off the idle circuit when you stop, to prevent `running on`)

Re: fuel pump

Posted: Sun Oct 10, 2021 2:48 pm
by B@fink
Well both of them don’t work so good then :xd: :xd: might be worth trying another new pump I suppose. Wasn’t a cheapo no make neither, ah well, some you win, some you lose.

Re: fuel pump

Posted: Sun Oct 10, 2021 6:45 pm
by Mc Tool
Lektrik solve a few issues :D and not hard to do

Re: fuel pump

Posted: Mon Oct 11, 2021 9:33 am
by Bug
Have you tried taking the petrol cap off and listening for a hiss?
It is possible that the tank vent is blocked and creating a partial vacuum to pull the fuel back through.

Re: fuel pump

Posted: Mon Oct 11, 2021 9:43 am
by stevemarl
Bug wrote: Mon Oct 11, 2021 9:33 am Have you tried taking the petrol cap off and listening for a hiss?
It is possible that the tank vent is blocked and creating a partial vacuum to pull the fuel back through.
Excellent!!!! I would never have thought of that: see how important it is that people such as yourself Martin, continue contributing.

Re: fuel pump

Posted: Mon Oct 11, 2021 1:22 pm
by Bug
stevemarl wrote: Mon Oct 11, 2021 9:43 am
Bug wrote: Mon Oct 11, 2021 9:33 am Have you tried taking the petrol cap off and listening for a hiss?
It is possible that the tank vent is blocked and creating a partial vacuum to pull the fuel back through.
Excellent!!!! I would never have thought of that: see how important it is that people such as yourself Martin, continue contributing.
Aw shucks. Pretty unlikely to be honest. But once in a while I get the answer right. Got to keep an eye on you lot, even though now I'm tinkering with BMW straight-six motors in Z4s. :?

Re: fuel pump

Posted: Mon Oct 11, 2021 4:31 pm
by B@fink
Brand spanking new tank. And did it with the old one that had turned into a teabag. I think that will be ok. But I’ll try owt once!

Re: fuel pump

Posted: Mon Oct 11, 2021 5:23 pm
by pbar
stevemarl wrote: Mon Oct 11, 2021 9:43 am how important it is that people such as yourself Martin, continue contributing.
Certainly agree with that, definintely. Well said.

Re: fuel pump

Posted: Mon Oct 11, 2021 6:02 pm
by Mc Tool
dont worry , Im not going anywhere :xd: