Thread: Will a bung lift pump still prime fuel manually?

The 300Tdi should bleed itself when running. It sounds like you are getting air somewhere.

Manual priming the lift pump can lead to failure of the rubber diaphram. The rubber ages, and manual priming usually flexes it beyond it's normal working stroke. A split diaphram lets diesel fuel into the sump and can lead to engine problems from the contaminated oil.

Thanks bush65, i will leave the lift pump alone from now on.

I am almost at the point were i want to pull all the fuel hoses out to see were the problem is. Is that a good idea or a tough job?

From what i gather there are 2 main lines that run under the drivers side, 1 to the lift pump and the other to or from the injector pump. Good idea to pull them out or leave to a mechanic?

I think you are right, must be getting air from somewhere.

Thanks again

Should be one line from tank to lift pump to fuel filter to injector pump to engine. The second fuel line is the return line running unused fuel back to the tank.

Check filter under screw on top of lift pump, it can get clogged with gunk. Check connectors in and out of lift pump, on some Disco's the lines were too short and crack easily near the join. Change fuel filter if not done recently. Can't recall if there's another filter under the inlet on the injector pump.

Check fuel tank for blocked breather - tank sucks air when you remove filler cap after a drive.

Cheers
Simon

The filter is new, already replaced even though the original like the sedimeter was very clean. I haven't dropped the tank want to avoid that but found the hose that runs from it and it is not blocked and after blowing in it and sucking it (yuk!) i would think its not blocked at all.
Whats next?
I took another close look at fuel lines and couldn't find anything sus, they all look like they have never been touched.

If there is a leak it must be between the tank and the lift pump. Most likely between the filter and the lift pump. I have had a filter/sedimenter leak air when replaced.

If you have an air compressor, pressurise the tank slightly with the engine shut off. You should be able to see where the leak is then.

The car has had this problem from when i got it, doing the sedimenter, filter and other various checks have done nothing to fix the prob. There are no obvious leaks apart from the one i fixed on the return line.

Good idea about the compressor, only problem is i dont have 1. I do have a bicycle pump

What ever i do i have only have 1 day left before i go back to work. I can hear the fuel running through the pipes in the engine bay and injector pump after i turn the engine off.

Steve

Don't know if this is useful but recently noticed drips under defer on garage floor-initally thought just a small oil leak .Then observed that spots on the floor didn't look like oil.Mentioned it to my mech who when up on the hoist traced it back to lift pump.It was being blown back and was dripping in the front of the transfer to the floor-was leaking from the pump around pump lever.Hadn't affected performance but new pump solved the problem
Cheers,
Mary

Wow thats making me think.
I recently replaced the seal at the front of the transfer case because it was leaking badly, but when i got under there today i noticed a small drop of fluid i thought it was some TC fluid, hopefully it's diesel. I noticed a bit of the black stuff on the block just under lift pump. Hope the leak is there.