Early Ford pumps used the pressure in the pump to retard the timing to nominal(on a diesel you advance the injection to start).If air is getting into the system it can cause the timing to change and the engine to surge.This type of pump required the throttle pushed to the floor to start so you got maximum advance and fuel;later ones with mechanical advance(cable from solenoid or directly by electrical connection to the pump) required the foot to be left off the accelerator.

Yes you seem to be pointing at what I was thinking.

In fact I had already replaced all the diesel pipework inside the engine compartment except the ones linking the injectors and the return which goes directly to tank if I am not mistaken, therefore shouldn't influence. Also fuel filters have been replaced around a million times to no avail.

This problem had arisen when sometime back I had found the manual pump bellow above the fuel filter had burst.

The mechanic had told me that I had to replace the whole fuel filter module. We did that and installed a clear glass type one (make = Lucas????).

But from then onwards the engine developed this strange behaviour and every now and then just increases the revs and I control it by engaging a gear and genty apply brakes to help it die down. At this point I also replaced the pipework as stated and have observed tiny bubbles coming out of the fuel pump but never coming in.

After that, recently I had found that the replacement manual fuel pump bellow developed a leak and was leaking fuel and therefore presumably leaking air in when in suction. I replaced again the top part of the fuel part including all the seals even the one below the glass bit, but I am still observing the tiny bubbles coming out of the fuel filter.

I know that maybe I am getting paranoid, but I had also observed tiny bubbles coming up from the bottom of that metal tube inside the glass compartment of the fuel filter. Obviously air will go up. Is it possible that it is gradually accumulating forming a bigger bubble and then suddenly this gets sucked in?

Is it possible that this type of fuel filter arrangement has a manufacturing defect?

Well I might have mislead you. The actual filter is a normal one made of that paper like material.

The glass is just the container it is installed in. I am not referring to those small oes made of glass mate.

The original one was the can type that you screwed in directly but now this requires only the interior to be replaced.

Edited by JDog on 07/12/2010 at 12:14

problem seems to have been solved by diesel pump service. crossing fingers :)