BMC 1.5 Thornycroft t90 problem with fuel system

[CAPTAIN FANTASTIC]

I changed the main filter (Delphi 296) and then run the engine for about half an hour; no issues. Next day, I started the engine and it run for about 5 minutes and then stopped; it does not start. Never had issues before, so I presume the problem is due to the change of the filter.

The Filter is full of fuel, no air. I slackened the nut of the pipe that feeds fuel from the main filter to the lift pump; there is fuel coming out. (The fuel level in the tank is above the filters, lift pump and injection pump.) There is fuel going into the fuel lift pump and coming out.

The pipe from the lift pump to the secondary filter (secondary filter is mounted on the engine) is full of fuel, but when I prime the lift pump (using the pump hand lever), very little fuel squirts out and no pressure. Even when I crank the engine with the starter motor, very little fuel comes out from the pipe; so it appears that there is no fuel from the secondary filter to the fuel injection pump. I have slackened the air bleed screw, but, no fuel comes out when I try to prime the system using the hand lever on the lift pump; even, cranking the engine makes no deference.

Am I correct to assume that there is problem with the lift pump?. Easy to get a replacement; £30 from asap.

 

[CAPTAIN FANTASTIC]

This is the my engine, showing the filter etc

 

[rogerthebodger]

That's where I would look, It could be just some muck in the exit valve or the valve is faulty or the strainer in the pump is blocked.

 

[QBhoy]

Keep pumping with the bleed open before the rail it should come through eventually. Then of you need to, crack open the injector fittings slightly but not completely. Have someone turn her over and get ready to tighten them as you see pulses or she fires.
or you are drawing air at the filter you changed.

 

[QBhoy]

Did you change the seals on the filter like for like or as it was ? Sometimes get a seal in the box for a different application that’s not required.

 

[CAPTAIN FANTASTIC]

I have checked the filter to ensure that it sits properly, top and bottom ; I used the new rubber seals of the same size. The problem is that I can not use the lift pump to bleed the engine; the lift pump doesn't seem to be able to pump fuel; its hard to tell, but perhaps, I should replace the lift pump as it appears to be the original!!.

 

[QBhoy]

The lift pump will struggle to pump of its dry. Not good for it either without the diesel lubricating it. Is there no manual priming hand pump in the line ?

 

[guernseyman]

Have you considered that the engine-stop solenoid may have failed? I believe it is spring loaded, and the default is stop.

 

[colind3782]

If the lift pump diaphragm has failed you will probably be getting fuel in the oil. Check the dipstick. Does it smell of diesel? Are you "making oil". Is there resistance when you use the lever on the lift pump?

 

[CAPTAIN FANTASTIC]

Thanks for all the replies and suggestions;