Help intermittent fuel problem

[stanleeds]

Hi everyone - I have 2.5 diesel automatic. For the last 6 months I have been struggling with an intermittent fuel problem. The Bongo drives fine but when idling in traffic for any period of time the fuel pressure seems to drop (the rev counter dips) it will eventually cut out. It does start again and but with some difficulty and will eventually clear itself. My garage have explored a lot of possibilities but are pretty convinced it is a fuel transfer problem. I have had a new fuel pressure regulator fitted and everything was hunky dory for a few weeks and it started happening again. They have now fitted a an electric pump to ensure that there is a constant fuel transfer - but this does not explain why there was a drop in pressure in the first place!! they said that worse case scenario it may need a new mechanical pump but this may be expensive.
In short it loses fuel pressure only when hot (idling in traffic)
Difficulties starting again but will eventually clear it self
Fine on long stretches

Also any idea what a new pump would cost?

Any ideas on this would be gratefully received. I have agreed a sale on this but I am not convinced that the electric pump is the answer. The prospective buyers know about this1

[wonkanoby]

try it without the fuel cap

as breather may be blocked

[missfixit70]

Have you changed the fuel filter? If so are the sealing rings in the right place?
Have you checked/cleaned the banjo filter on the forward end of the top of the fuel pump?
Is there any sign of fuel leakage around the fuel pump? common issue for the seals to leak, they can be replaced in situ.
All these issues are covered by factsheets in the members area or by doing a search on the forum.
Also worth checking the fuel hoses aren't leaking, supposed to be replaced every 4 years.

[dandemann8]

Bloody hell Lord Lucan's back, O sorry I mean missfixit70 , where you been hiding

[321Away]

If your front seal has gone in your fuel pump, putting an electric pump in line will force diesel past he seal and into your sump!! so make sure you keep a close eye on sump levels.

Try replacing the fuel return pipe with a clear pipe and check to see if you have bubbles in the fuel, if so its your front seal.
Julian