The Fordson Tractor Pages Forum

I am working on a International B275 diesel fitted with a CAV rotaty pump, which i have had overhauled, also the injectors have new nozzles on and the timing is set (i think) I have fitted new piston rings the problems I am getting are misfire on a 1 if not 2 cylinders and also 2 cylinders are getting way to much diesel, also the engine stops when the tank gets to just under half empty and refuses to restart until more fuel is added. it ran briefly yesterday with no trouble sounding lovely only to start misfiring yet again

Any help would be grateful

I had a somewhat similar problem with my Super Dexta quitting when the tank was half empty. The fuel filter/water separator housing was made of plastic which had very small, fine cracks and this was allowing air into the system. All would be well until the fuel in the tank got down to the level of the fuel filter, at that point the injection pump would suck air though the cracks. The filter did not leak.
Check your fuel supply line very carefully to make sure no air can be drawn in.
The other problems you describe are beyond me, sorry.
Terry

The DPA will meter the same amount of fuel to each injector so you should not have different amounts to each injector, the pump should have been tested and the delivery amounts measured on the rig.

Wonder if you have problems with the pre heat coils or even the injectors themselves.

There should be a lift pump on the B250, you might have the valves in the pump sticking. If this pump is faulty and not keeping the correct pressure to the injection pump it could cause a misfire on random cylinders. I once had a DPA like that on a Claas combine with a 6.354 Perkins. In that case I took the gasket off the lift pump mountig and replaced it with instant gasket to cure the problem, but that one had a different lift pump drive.

I shall expect a credit in your next article if I am right!

Brian wrote:The DPA will meter the same amount of fuel to each injector so you should not have different amounts to each injector, the pump should have been tested and the delivery amounts measured on the rig.

Wonder if you have problems with the pre heat coils or even the injectors themselves.

There should be a lift pump on the B250, you might have the valves in the pump sticking. If this pump is faulty and not keeping the correct pressure to the injection pump it could cause a misfire on random cylinders. I once had a DPA like that on a Claas combine with a 6.354 Perkins. In that case I took the gasket off the lift pump mountig and replaced it with instant gasket to cure the problem, but that one had a different lift pump drive.

I shall expect a credit in your next article if I am right!

Hi Brian

I will certainly put in a mention for you and the site in my next article, My thoughts had turned to the lift pump I have stripped it down and found loads of c##p inside and the 5-6 flat head bolts that held the unit togther were loose so ?? will let you know how I get on.

IMHO I think it would be down to a poorly performing lift pump where the 'head' of diesel when the tank was full was making it easy for the lift pump to pump to the FIP. As the fuel went down the fuel pressure from the tank to the lift pump reduced and so less fuel got to the FIP.