I have a 1986 GTi Cabriolet which has killed 3 high pressure fuel pumps in the last 3 years. I’ve replaced the fuel tank, in tank lift pump, swirl pot, accumulator, fuel pump relay and fuel distribution diaphragm in multiple attempts to find the cause. The pumps never die when running the car, but after standing unused for a few weeks. Any thoughts?
My initial thought was ethanol, but I’ve always run the car on E5. 2 of the pumps were genuine (expensive) Bosch, one was an EBay £50 job.
how do they die exactly, no noise at all, or very loud noises, or just no pump output? have you tested the lift pump to ensure its delivering the correct volume of fuel: easiest way to jump the the pump is swap the fuel relay in slot 2 with the x-contact #17/18 relay in the slot below it, then pump will run all the time with ignition on
In tank pump is fine it seems. Main pumps either die completelely (2 of the 3) or deliver (current one) 5psi.
Good point by RJ. If the in tank one is struggling, the external one is working a lot harder than it's supposed to.
hmm. are you re-using the non-return valve (fitting on pump outlet) as mine broke on me cutting all fuel flow from the pump. doesnt explain the ones that are completely dead though... did you try jumping them from battery direct and also reversing the polarity as sometimes if they have debris caught inside this can dislodge it (again, why wait till switch off to do this?)
Yes, all the pumps I’ve fitted had the non return valve. Tried reversing polarity with the pump off the car - dead ones remain dead, 5 psi one doesn’t change.
Nnnnooooooooo……… Have you got a blockage upstream? My fuel pump struggled as I had a kink in the pipe (not a VW) and the pump sounded terrible. Freed up and less strain. Perhaps test your pressures/flow at the engine end?
