So my car's stopped firing. The pump still runs with some humming noise. Fuel pressure between the pump and the regulator is about 20psi only and zero after it.

Please PM me if you have a good one hopefully at reasonable $$.

Thanks for looking

Is your FP in the engine bay or up front?

You might want to first check both: the Regulator (since it's 20# on one side & 0# the other); & then if the pump is cavitating due to air/vapor bubbles in the gas lines when hot (notorious 914 vapor lock problem & makes FP hum) - before you replace the pump!?

Vapor lock is notorious in the rear mounted fuel pumps due to the engine's heat, which is why Porsche moved them to the front trunk in 75-76 MY, & why many of us moved them forward on earlier models!

Tom
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PS - If it has "stopped firing" - then you have an ignition problem too or instead -
... or was that just a general form for not running?

Thanks for the advise.

On my car the Fuel Pump is located in the engine bay and this is happening on a cold engine. I don't see fuel on the return line just after the #3 injector.

Oh, I've just replaced the fuel lines in the engine compartment so I am pretty sure there is an air in the both lines but they must not be pressurized.

I've cleaned the electrical contact of Fuel Pump and checked the hoses if they are kinked or pinched but they seem fine.

I've read somewhere that D-jet Fuel Pump should produce 50psi if not regulated.

That is why I am looking for a replacement. What else should I look?

thanks!

A dirty sock in the tank. No fuel supply = noise and low pressure. Either way, with 20 out the pump, you should have 20 out the regulator. I would double check your fuel line routing. Did it happen when you changed the lines?

Mr.underthetire,

You're absolutely right. And I was totally wrong about the direction of fuel flow. The supply and return lines were connected wrong. It is now corrected and the engine runs just fine with 29psi fuel pressure.

Thanks for leading me to the right direction.

I guess I do not need a new pump right now.

Well, I'll bet your happy about that!!!!

It always helps to check the simple s**t first, & any work you've just done or had done (I didn't catch initially that you'd replumbed you lines).

Do still check the "sock" in the tank (fuel outlet line filter screen) if you haven't already as "under" suggested. If it's torn, holed or corroded - you can save yourself future grief of debris getting in & fouling injectors, etc. by replacing it. Replacement socks sold at AA, PP, Peli, etc.

If you ever have hot weather running problems - say when you go inland from Bay Area coolness, then you can get a fuel pump relocation kit at AA & maybe others too, for when you're feeling ambitious to work on something again!

Here's why - back in the day (late 70's) I got stuck in Blythe on the way to the River (Colo) to water ski & had to cool my heels at the Denny's for a couple of hours until things cooled down and the vacuum lock relieved & it started again 2-3 hours later! So I asked my German 914 expert mechanic & he hit the FP problem & relocated it up under the steering rack cover on the floor pan behind the ZF rack - & nary a problem since!

Cheers!
Tom T
Orange CA
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