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> Fuel pump help, Please
rhodyguy
post May 20 2018, 04:12 PM
Post #21


Chimp Sanctuary NW. Check it out.
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After the FP reg the fuel SHOULD flow unrestricted back to the return, as opposed to the supply spigot on the fuel tank. You should not be overthinking the 'Y' thing.

Where are you pulling the pump power from?
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ndfrigi
post May 20 2018, 04:13 PM
Post #22


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QUOTE(gster @ May 20 2018, 02:07 PM) *

QUOTE(Dave_Darling @ May 20 2018, 12:25 PM) *

Let's summarize things a little bit here.

- The original pump had three ports. One was intended to dump extra fuel from the pump back into the fuel tank. They later figured out this wasn't really needed, which is why pretty much all fuel pumps are now two-port pumps.

- The 914's fuel system works by the pump pressurizing the fuel, and the pressure regulator acting as a flow restriction or blockage, like putting your thumb over the end of a garden hose. Any excess fuel that gets through or past the restriction is dumped back to the tank. That's what the return line is for.

- If you split the outlet of the pump and run one leg of that back to the tank, the majority of your fuel will take the easy way and wind up being dumped back into the tank. You will have very very low fuel pressure.

- If you take the outlet of the fuel pressure regulator and hook it back into the outlet of the pump, excess fuel will go straight back into the high-pressure loop of the fuel system and the pressure will build until the pump cannot push any more. You will have very very high pressure.

In this situation, you should get rid of all of the "T" and "Y" fittings in the fuel line except for those at the fuel rails. (The fuel rails, more or less, are complicated T fittings.) Run your lines from the tank, to the filter, to the pump, to the fuel rails, to the pressure regulator, and back to the tank.

--DD


Thanks
That's a most consice explanation.

I'll have to find that T in the return line and eliminate it.
Any idea where it might be?
For the sake of discussion, would the return line not
be under very low pressure?
I.E
The pressure regulator maintains @ 35 +/-
and the excess is returned at 5 +/- to the tank and
this extra line I've cobbled together.
Also, I appreciate everyone's concern over the lines.
Braided lines are original and new pieces are
SAE 30R7 50 PSI
I do have a fire extinguisher in the car as well.


I think the T or Y split is under the fuel tank unless if the previous owner installed 3 fuel lines inside the tunnel lines from engine compartment all the way to fuel tank area.

I think also the FI fuel pressure should only be between 28 to 32. 35 psi can be too high. Fuel pressure regulator can be adjusted to lower it.
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TheCabinetmaker
post May 20 2018, 04:36 PM
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Why do you need to "find the T" when you just posted a pic of it? Are you here just to waste our time?
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porschetub
post May 20 2018, 05:02 PM
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Surprised it ran @ all with that contra flow ,I agree it needs to be checked for pressure,I've experienced 2 types of carbs pumps that made more than there rated pressure.
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