Diesel fuel supply

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boyfleming
Posts: 2
Joined: 29 May 2005, 19:10

Diesel fuel supply

Post by boyfleming » 29 May 2005, 19:27

Hi. My 1.9 diesel was running fine. Yesterday morning it started first time, ran for a couple of seconds and then died and would not restart.
It has a Rotodiesel fuel filter housing with a manual pump that is just a 1" black button, rather than the unscrew shaft type.
First I though I had a fuel airlock and then I changed the fuel filter. In both cases I went through the priming procedure, first pumping and bleeding and then pumping with the solenoid activated (ignition on to light the glow plugs).
The engine will start when primed as above but still only runs for a few seconds (until the primed fuel runs out?). Once it stops, if I open the bleed screw, there is air again in the fuel filter housing.
I can think of 3 causes and wonder what your thoughts are?
1) Fuel pump has failed and is not pumping fuel - although it seems strange it would happen to fail while the car was parked and not have shown a fault when driving the previous day.
2) The priming pump button is letting in air - when I pump the button to the point fuel is pumping past, fuel leaks around the button, so surely is letting air in?
3) The fuel solenoid is stuck shut, only opening and allowing fuel past when I open it for the final priming (with the the ignition to glow plugs) - but does the solenoid not close at final prming and open when de-energised?

JohnD
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Post by JohnD » 30 May 2005, 00:11

You've obviously got a massive airleak. The solenoid opens when the ignition is turned on and should stay open until turned off. If it didn't open, you wouldn't be able to start. Check the hose from the tank - the rubber one which goes from the top of the tank down to the hard pipework. Get to it under the back seat. If it needs replacing, tie a string to it before pulling it out. Also check any other rubber hoses. If you suspect the priming button is leaking, smother it with grease )temporarily)

boyfleming
Posts: 2
Joined: 29 May 2005, 19:10

Post by boyfleming » 01 Jun 2005, 01:38

Hi John.
You were right about the air leak which must have been somewhere in the fuel filter housing. I replaced it today and the engine runs.
I think the rubber diaphragm under the Roto-diesel priming button must have sprung a leak. I am not sure if this is a design weakness - my replacement has reverted to the old screw in pump type.
I think the diaphragm was due to me not replacing the fuel filter for the last 25k miles causing higher pressure to pump the fuel.
Cheers,
Andrew.