My VW (81 Rabbit Pickup, Caddy) had an auxiliary fuel lift pump installed in the past. I presume the fuel pump in the IP is no longer working. My auxiliary pump started not giving enough pressure to push the fuel through the fuel filter, even with a new filter.
I installed a Holley auxiliary fuel pump. It seemed like a good idea at the time. But now I see there are some mixed reviews on it. Time will tell how long it lasts.
Anyway, I thought I would try it without a pressure regulator.
That is a very bad idea for the classic VW injection pumps...
The front shaft seal on the IP pump started leaking like a sieve (fuel pouring out of the front of the engine).
Anyway, the Holley Lift pump came with a Holley Pressure Regulator.
I've now installed the pressure regulator downstream from the fuel filter, but upstream from the IP at the lowest setting possible, about 3 PSI.
I also replaced the fuel line from the fuel pump to the engine with translucent 3/8" PEX.
The IP seems to be holding.
The fuel filter isn't leaking.
I should get a spare IP seal in stock soon... in case I blow the seal again, but for now it is fine with the original seal. Other than timing issues, it should be easy enough to replace the shaft seal in the future. Perhaps I'll replace the timing belt and the shaft seal together in the near future.
I don't think the VW IP needs a lot of pressure so personally I'd like to drop it down a bit further, perhaps to 1-2 PSI, but that will be a future project once I find an appropriate pressure regulator (or learn how to modify the Holley for lower pressures.
I suppose my idea now is that the increased pressure from the Holley fuel pump should help compensate if the fuel filter starts partly clogging again.
The 3/8" PEX is a little big, and tends to trap air bubbles, but they disappear once the engine is started. 1/4" or 5/16" might not trap the bubbles as badly. However, I was having troubles finding the correct hose barbs, crimps, and etc for the 3/8" tubing. Smaller tubing would be even more difficult to find. I ended up soldering a 3/8" barb onto my VW banjo joints. I found a crimper that fits in a vise that works well for crimping the pipe bands. However, I couldn't find any 3/8" crimps. I made some Crimps out of cutting about 3/8" long chunks out of the blue (thicker) 1/2" copper pipe, then cleaning the hacksaw burrs off. So far they are excellent. The hose slides onto the barbs best when dipped in hot water.
Anyway, it is all working, and I now have some practice that might come in handy with future projects.
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