Is it possible for the fuel pump to be knackered and not have enough pressure to pump past the fuel pump check valve? Ive had it off and cleaned it out and with the pump running (relay bypassed) no fuel comes out of the outlet but it pumps the fuel back up the return pipe to the fuel distributor? My logic is that it doesnt have enough pressure to move the ball bearing i. The valve so it pumps it back to the return? but even that seems highly unlikely.
yes, but it could be the check valve itself is the problem I had the very same issue on my mk1 golf cabrio. I tried a MK2 check valve from a spare kjet pump I had lying about the place and sorted
Above the fuel pump whats that box above/on the side of the tank where the fuel line return from the engine bay connects and the inlet for the pipe? Seems weird that an inline pump can send fuel back up the line its drawing fuel from?
this is post-84 cabrio/scirocco then? if so thats the fuel reservoir/swirl pot, my guess is the pump has some kind of bypass valve built in so over-pressure can be sent back to the feed side?
Sorry it didnt add the rest of my first post its. 1985 cabby gti so 1.8 8v. yeah that makes sense just dunno how its possible to send it back down where its getting fuel from. Ive had check valve off and it moves freely with a blower down it. ill try a new one cant be expensive unlike the pump
No sorry its 1985 cabby gti so 1.8 8v. But it doesnt have a lift pump in the tank only has the sender unit under the seats. The fuel going back up the return isnt high pressure just like a tap flowing.
it should have a lift pump in the tank if its a post-84 cabrio, this is what fills up the swirl pot. if this is missing it would mean the main pump will struggle and eventually die. If its missing this would suggest someone has been silly in the past or else the car was originally a carb and not converted properly... a clue is the proper cabrio gti will have a 3rd wire to the lifter pump area for the lifter pump, a carby will only have 2 wires
i lifted the rear seats and all thats there is a panel under the os and under that the fuel sender. i read that lift pump is under passenger side but there isnt even a blank plate there
Aah right cheers. Could it be that pumping the low pressure fuel im gettin to the return then? What do think the chances of the chwck valve being ****ed are seeing as ive cleane it out an the spring and bb move freely?
could well be aye, disconnect one of the wires to the main pump and bypass your relay again to make sure the in-tank pump is running. an easy way to do this is swap a 17 or 18 relay into the pump socket this will make the pumps come on as soon as the ignition is on. iirc I could find nothing wrong with my check valve either, but put a new one on and all sorted! to test it i tried bypassing the relay again once the check valve was removed = loads of fuel came out. valve fitted = nothing! I cant see how it could fail really as its only a ball and a spring as you say, but oh well I wasn't going to waste time looking at it once the replacement valve solved the problem on some main pumps there is a wee mesh basket in the inlet pipe on the pump so its worth checking inside there for debris.
I found a replacement pump with a new valve so ill give that a bash as it wasnt too dear. cheers for the help mate ill report my findings
