Fuel Pump Mystery

[John912]

About two years ago I finished restoring a 65.5 911. It included a new Facet fuel pump, but it stop running a few months afterwards. I replaced it with a similar pump I had in inventory for my next resto. The same thing happened, it stopped running after a while. As part of the resto project I had the fuel tank coated with the red stuff, and installed a screen filter before the pump. I have a third Facet pump I use to transfer fuel when needed around the shop, and installed that one – but same thing happened. The pump starts to run quiet, then comes back to life (sometimes) when you tap it. Same thing happens with the other pumps. I tested the ground from the pump to the body stud, and it’s solid. The filter screen before the pump is clean. I examined the filter in at least one of the pumps, and it’s clean. I replaced the terminals in the positive Y connector supplying power to the pump and tested that I have power. I’m baffled!

[NeunElf]

I have an actual Bendix pump in my '65--I'm guessing that you have the "Bendix continuation" Facet fuel pump.

or

Is it possible that nothing is wrong?

My Bendix pump slows down when the float chambers in the manifolds fill up and the needle valves close. In fact, part of my starting routine is to wait until the fuel pump's ticking slows down.

Some of the Facets are billed as "electronic." Maybe they'll just shut down when they reach full pressure.

Is it's possible that this is what's happening? To verify this, you might try running a hose from the outlet on the bottom of a float chamber to a safe container so the float chamber can't fill. If the pump runs continuously you're good to go.

[John912]

Yrs Jim, all three pumps are Continuation version. And yes something is wrong because the car stops running. When it does I could hear a faint or no sound from the pump (with key on). I usually get it going again by tapping on the pump.

[ejboyd5]

Do all three pumps run correctly when you are transferring fluids in your shop? Do they malfunction only when installed in the car?

[NeunElf]

Yrs Jim, all three pumps are Continuation version. And yes something is wrong because the car stops running. When it does I could hear a faint or no sound from the pump (with key on). I usually get it going again by tapping on the pump.

That's not good.

Maybe it's fuel contamination, maybe it's low voltage, maybe a combination. Or something else.


A while back I searched the web for Bendix Pump advice and saved Bendix_Pump.pdf if it's some help. I also found this diagram (which mightn't apply to an "electronic" Facet):

[chris_seven]

Dry joint on the pump?

These Facet-Puralator pumps don't have the best reputation for reliable operation.

The original Bendix pump was a Silver Top with relatively low pressure.

Some of the 'cheap' Chinese copies are not too bad now, and look correct. The max pressure can be reduced by changing the spring.

You can buy one from Australia with correct style, the M12 Unions and a Bendix sticker on EBay from Australia and they seem OK

https://www.ebay.co.uk/itm/Porsche-9...gAAOSwHjNWCKuA

[John912]

Do all three pumps run correctly when you are transferring fluids in your shop? Do they malfunction only when installed in the car?

Thanks, I ran it for 30 min as shop transfer pump as test with no issues, but then again I can also run it in the car for several 30-minute drives with absolutely no issues. Last time I went to start it after a successful drive it was dead, until I tapped it with a wrench and it started back up.

[Merv]

My pump! 4 years no problems.

[Will 1967]

How did this end up?
I have now 2 failed Facet Silver tops (lower pressure version i.e. 4-5psi and correct pressure at carbs) in 2 days, same thing happened to first one that it started to be very quiet so nothing came out, hit it few times with wrench and it came back alive for few mins. Exactly same symptoms as with OP.
Total running time maybe 3 hours for the first pump.
Decided to change that one for a new one, that failed after 30mins and not coming alive. Both make very quiet ticking noise after fail, like 75% less noise vs when running normally and nothing comes out. And then yet again works ok with another new pump. Tank is new and cleaned, tank screen new and cleaned etc.

Totally fed up with these now, I would like to avoid pressure regulator but probably will hide RELIABLE pump hidden in front behind suspension protection plate and leave Facet (Bendix) just for show and as filter. Or take the risk and mount one new Facet at original location and one Facet behing protection plate (edit: where it won't fit so have to be in smugglers box) so there would be back-up pump. You can "suck" fuel through Facets but not sure about Pierburg etc aftermarket ones. Only good thing about Facet in engine compartment is that its quick to change after fail (which seems to be needed every few hours )

Any suggestion for low pressure reliable fuel pump? (Don’t care what it costs, not cheap to go through Facet pumps nor funny at the roadside)

Everything in car is new or restored, and these are original Facet pumps for sure.

[Haasman]

Could it be a venting problem with the tank? The pumps work "on the bench" but fail in the car, could it be a venting to the tank?

Has anyone tried running without the fuel filler cap to test for a venting issue?