Bleeding Fuel System (Take That How You Like)

[pw8757]

I'm just putting the final touches to an engine out clutch replacement.

The engine won't start. The shut-off solenoid is connected and clicking when the ignition is on. The engine turns over.

I've followed the Haynes on bleeding the fuel system, but it's the first time I've done this. (it's my first diesel car)

I'm operating the priming lever - should this need to be pumped for minutes at a time? Is it like bleeding brakes, ie you have to close the bleed nipple after each pressure stroke?

Is there (I sincerely hope so) a shortcut tip some wise owl on here might know?

[Snagger]

As long as you're sure the unions are all tight, the easy way is to open the bleed and spin the engine on the starter for a few seconds at a time, letting the starter cool 30s between each spin. After five spins, let the starter cool for five minutes, then have a few more goes. Once the engine fires, let it idle with a rag around the filter to catch the spillage while you let the bleed weep until clear of bubbles, then nip it up.

If you can't get the engine to start after five cycles of five, then you have a more fundamental fuel feed problem. You might want to have a battery charger available before doing this.

[pw8757]

Thanks.....will give this a go!

[C18RCH]

Even if the fuel solenoid is clicking, it does not mean it is working correctly when you are turning it over. Mine was working fine when I tested it by applying voltage, but wasn't receiving any voltage when turning over as a result of me connecting it to the wrong pin on the back of the ignition.

[Snagger]

Even if the fuel solenoid is clicking, it does not mean it is working correctly when you are turning it over. Mine was working fine when I tested it by applying voltage, but wasn't receiving any voltage when turning over as a result of me connecting it to the wrong pin on the back of the ignition.

I got the impression there is a lack of fuel supply to the filter, rather than the injectors. Certainly, a faulty solenoid or blocked fuel passage could prevent fuel flow like you say, but if the filter bleed is not producing fuel on priming activation, then it points to a problem further back.

The first thing to check is that the fuel lift pump itself is working. If the engine is stopped with the pump cam in the "wrong" position, it prevents the pump from being hand primed. Turning the engine over one turn on the crank shaft will eliminate that issue, but the easy way is to crank the engine on the starter to see if fuel eventually emerges.

If no fuel does emerge, then fuel is not getting to the lift pump. That has to be due to:

1) Air leaks in the feed line, allowing the pump to suck air instead of the heavier fuel. This could be a split of chafed hose, a leaking union or joint, or a corroded pick-up pipe inside the tank:

2) Blockage in the pipe or the pick-up pipe gauze strainer in the tank (disconnecting the feed pipe from the lift pump and blowing back through should indicate if this is the case);

3) Failed lift pump, through a split diaphragm or failed non-return valves, which can be checked by smelling the sump oil and looking for raised oil levels on the dipstick (a split diaphragm will cause fuel to leak into the engine crank case and sump) and by disconnecting both pipes from the lift pump and priming the pump by hand, feeling for suction or pressure on the respective ports with a finger pressed over said port.

[C18RCH]

Yeah, agree with all above but the hand pump is worse than useless. I could not get mine to get the fuel through the filter. In the end I made up a clear pipe which fitted the fuel line and sucked it through. This was of course because the main fuel pump would not pull the fuel through because the solenoid wasn't working under cranking.

If it is, as you said above, the easiest way is to crank the engine a few times.

[Tanuki]

How long did your clutch-change take? I've known the valves in the lift-pump to stick if they've been left 'dry' for a more than week or so with no actual fuel in the pipes.

If you're not getting a positive-pressure supply of diesel from the lift-pump with a good flow, you're unlikely to get the engine to start. The injection-pump behaves very badly if at all if it's expected to 'suck' diesel into itself rather than being fed a steady supply of diesel under pressure from the lift-pump.

[pw8757]

Thanks all!........I've been "under the radar" this week, so haven't been able to do the courtesy of saying how much I appreciated the advice received.

Engine cranking until fuel flowed worked - bubbles, then flowing diesel - I totally agree about the hand pump.................

Perhaps next time Mr Haynes is updating his manual, he might change the advice in his paragraph..... :-)