Massey 240 Fuel Issue

[MasseyPerkins]

Tractor died. I was low on fuel but only just touching the red.
Filled up with diesel and no fuel coming out of pump bleed.
No fuel coming out of filter housings after filters removed.
Fuel coming out of fuel tank drain tap.
Blew out air in tube coming from lift pump to filter, no blockage.
Fuel coming out fine from tank to lift pump, but no fuel coming out of lift pump exit.
Took off lift pump, soaked in petrol. Blew air into inlet, diesel blow out from lift pump exit.
Put inlet line back into lift pump, just a few drips coming out of lift pump exit.
Put lift pump back on, connected all lines and tried to use lift pump to send fuel to filters but only a few drips at filter housings.

Don't understand if I can easily blow air/diesel through lift pump, why gravity fed fuel is not getting through. Lift pump was replaced a few years ago and was genuine Perkins.
Thanks

 

[showcrop]

I opened up a lift pump once and found it full of mud. There isn't much to them. They don't cost a lot either.

 

[MasseyPerkins]

I think I've worked it out. Once the fuel from the tank reaches the lift pump, it gets atomised under pressure. This explains why the fuel coming out of the lift pump by gravity, is much slower than the flow going in except when I used compressed air.
To confirm this, I went and checked the glass bowl on the filter and sure enough it was full of diesel albeit that it had filled over a few hours. This explains why the lift pump needs the manual pump lever to force fuel under pressure when bleeding the system.
I did find some bits of plastic blocking the lift pump exit port when I cleaned it out...looked like the remains of the plastic pipe seal. I think I may have fixed the issue. Won't know until I bleed the system using the lift pump lever.

 

[Bob NY]

I think I've worked it out. Once the fuel from the tank reaches the lift pump, it gets atomised under pressure. This explains why the fuel coming out of the lift pump by gravity, is much slower than the flow going in except when I used compressed air.
To confirm this, I went and checked the glass bowl on the filter and sure enough it was full of diesel albeit that it had filled over a few hours. This explains why the lift pump needs the manual pump lever to force fuel under pressure when bleeding the system.
I did find some bits of plastic blocking the lift pump exit port when I cleaned it out...looked like the remains of the plastic pipe seal. I think I may have fixed the issue. Won't know until I bleed the system using the lift pump lever.

The lift pump does NOT atomize the fuel. It should send out a stream of fuel. The lift pump is actuated by a lobe on the the camshaft. If that lobe isn't in the right position, the pump won't do anything. Try turning the engine over a little and then try the lift pump again.

 

[MasseyPerkins]

The lift pump does NOT atomize the fuel. It should send out a stream of fuel. The lift pump is actuated by a lobe on the the camshaft. If that lobe isn't in the right position, the pump won't do anything. Try turning the engine over a little and then try the lift pump again.

Would you expect the gravity fed flow of diesel out of the lift pump to be about the same as the flow going into it or does the internal mechanism slow that flow without any foreign matter being present. I'm trying to find out if the slower flow out is normal (without engine running) or if there is still a blockage inside the lift pump.

 

[Bob NY]

The output of the lift pump will be pulses of fuel. The pump consists of 2 check valves and a diaphragm. I don't think there would be a steady flow thru it when the engine isn't running. Many years ago I had a diesel lift pump that wasn't "putting out". I took it apart and found that was full of something that looked and felt like vasoline. I cleaned it out and put it back together. It would shoot a stream fuel 4 feet after that.

 

[Bob NY]

Try cranking the engine with the output line disconnected from the lift pump. That will tell you if the pump is working or not.

 

[showcrop]

Would you expect the gravity fed flow of diesel out of the lift pump to be about the same as the flow going into it or does the internal mechanism slow that flow without any foreign matter being present. I'm trying to find out if the slower flow out is normal (without engine running) or if there is still a blockage inside the lift pump.

The output of the lift pump is EXACTLY the same as what is coming into it. EXACTLY! The difference is that the flow from the tank will be even while the output will be in pulses. The pulses get evened out in the filter.