2.5td 19j strange fault

My 2.5TD has developed a wierd fault. It will only start if I open the bleed screw on top of the Injection pump and close it when it starts. It runs well at tick-over and at higher revs, but when I stop the engine, even when its warm, it won't start unless I open the bleed screw again and it starts instantlyand runs normally. I've replaced fuel delivery and return pipes from tank to lift pump,filter, injection pump and back to filter. New copper washers everywhere, new boost diaphragm. Bled system manually,and using engine. Plunger removed from solenoid. Still won't start without opening the bleed screw on pump. Can anyone help?

I also have a problem starting. when cold I need to turn on ignition to prime injectors several times befit it will start. Then it was starting OK but now it is hard to start even with this. I have recently replaced the pump because it was the original with 240000 k on the clock and it was "singing" when in use. Now the new one does the same after 1000 k. A diesel mechanic suggested maybe a non return valve could be the problem but I don't know. any suggestions????

msomers said:

My 2.5TD has developed a wierd fault. It will only start if I open the bleed screw on top of the Injection pump and close it when it starts. It runs well at tick-over and at higher revs, but when I stop the engine, even when its warm, it won't start unless I open the bleed screw again and it starts instantlyand runs normally. I've replaced fuel delivery and return pipes from tank to lift pump,filter, injection pump and back to filter. New copper washers everywhere, new boost diaphragm. Bled system manually,and using engine. Plunger removed from solenoid. Still won't start without opening the bleed screw on pump. Can anyone help?

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On top of the filter housing is the bleed pipe connected with a banjo and a bolt, in the bolt is a very small hole which allows LOTS of air to exit the top of the filter but not a hell of a lot diesel. Poke this little hole through with a strand of wire and make sure it isn't blocked.

The Lucas CAV pump cannot deal with any air, that is why the filter has this system in place.

It sounds to me like there is air getting into the system that is being pushed into the injection pump.

Once you have bled it and got the engine running it will cope because of the flow of diesel through it carrying the air out, when you switch it off it will all gather and as you have found will stop you from starting it until it has been bled.

I would look for iffy connections, corroded unions on the tank etc.

If you are sure there is NO air getting in between the filter and the injection pump, and the filter head air bleed system is working it should all work fine.