Hi , I have a 1994 Fiat Ducato 1.9td with a strange problem, it won't maintain fuel pressure.
I am using a hand primer because I cannot find any sign of a primer on the lift pump or the filter housing.
When I do get the bleed hole full with the hand primer the system loses pressure over a few hours.
Have checked for leaks using the propane and carb cleaner method and found nothing.
Could it be a lift pump diaphragm fault?

Does anyone with a Ducato 10 know what this rubber plug is for on the pump, it's in the right place for a primer handle?

Mine used to drain back overnight when the leak off pipes had perished.
A lot of cranking and eventually it would splutter into life.
Not always a sign of leaking externally though.

I probably have to change them every year or two.
Just something about this one vehicle, others I have never touched.

Hi Mikey,thanks for the reply I was beginning to give up hope of an answer.
It's a strange problem,using a hand pump I tested the low pressure side up to the pump by capping off the supply pipe and it has no leaks, but when I reconnect the pipe to the injector pump and pumped the hand pump again there is air in the system.
It seems to be sucking air from the high pressure side which I didn't think possible.
Really scratching my head here.
Will look at the leak back pipes again although they are quite new.