Misfuelled XUD engine

[bertiewhite]

HI everyone, I've recently put petrol in my XUD engined 2002 Partner. I believe the engine was from a Berlingo but it's an XUD engine with a Lucas pump in any case. I still had about 10 litres of diesel when I put 20 litres of petrol in and drove for 8 miles before the engine stopped.

I drained the petrol using the priming bulb until just air was coming through, replaced with about 25 litres of diesel (is that enough?) and have primed the system as far as I can - the bulb goes fairly stiff but not rock hard. I tried a cycle of prime/crank the engine/prime and the engine seemed to be more willing to start with each cycle but doesn't actually start.

The engine WILL start & run briefly with cold start but then dies again so I'm wondering if I've destroyed the fuel pump? In order to help bleed the system I undid the injector pipe unions at the pump and expected to see fuel coming out whilst the engine is cranked over but there is none. Could it just be that there is still air in the system and the fuel won't come out of the pump without being compressed or should I still see some? I did whip the top off the fuel pump to see if there was anything obvious but that's provided no clue whatsoever except confirm there's plenty of fuel in it so I quickly put it back on.

So in summary - do I need to put more diesel in to increase the concentration? Should I persist with bleeding the system? Should I try a new pump?

How easy is it to change a pump?

Thanks in advance, Bertie

[spider]

Try using the primer bulb with the ignition on and seeing if any fuel comes back out of the fuel return pipe on the pump. I think it should still circulate through the pump.

On a Lucas pump there's a slight chance of shearing the driving cam / dog off if its starved of lubrication, this would scrap the pump (as a replacement would be easier and cheaper to get than to fix!) , you can tell if its this as the sprocket will not have much resistance although you'd have to take the timing belt off to check.

You may just have air locks. Tighten the unions at the pump (ensure the 'adaptors' they screw into are tight) counterhold them as you do not want them coming loose.

Slacken the pipes at the injectors by about a turn and put some rag around them. Ignition on and prime it. If its no better examine the fuel filter, make sure its actually full of fuel.

A vacuum bleeder can be helpful for this as you can "suck" the fuel up to the pump if not from its outlet.


Regarding changing it, its not difficult the only annoyance is one of the bolts I think on the bracket and may need to make a puller to get the sprocket off. If its marked where it is and the replacement is the same (avoid immobilised models) it should be near enough to run if you put it back where the old one was and a small tweak if needed for improved running.

[bertiewhite]

Hi Spider, thanks for your reply. I've been trying to bleed the system again and have noticed that no fuel is passed through the injector pump with both the solenoid energised and the throttle open when I squeeze the primer bulb. Should it be flowing through the injector pipes? As no fuel is apparent either when the engine is cranked or when it's primed maybe it is indeed pointing to an airlock or have I misunderstood how the pump works? Fuel filter is full and I've got fuel in the return pipe as well as the leak off pipes.

[spider]

The primer bulb will not pass fuel to the injectors all that does is force fuel to the pump which may then just return down the return pipe.

The leakoff pipes will tend to stay fullish anyway unless you pull them off. This is normal, do not worry about them as long as they are connected. You'll have running or starting problems (but not actual fuel "supply to injectors" problems) if there's a problem with the leakoff piping.

Throttle will not have that much effect really it will only increase the amount of fuel potentially being sent to the pipes.

Disconnect return pipe from pump, put it somewhere sensible and wrap a rag around it. Ensure its stopped dripping etc. Crank engine for about 5 seconds (no longer) then return and examine it for fuel being 'returned' down it.

If there's a full filter and the pump is full and fuel is present (it may not return if the pump drivedog is damaged) then it does point towards the pump being faulty as although it takes a bit to compress the air out of the higher pressure lines, there is usually some signs of 'life' ie the odd drop of fluid even after a few seconds cranking.

Be aware the primer bulbs can fail and the one way valve inside can collapse so fuel can run away and the filter seals can cause air ingress too however if you are sure the pump is full of fuel at this stage personally I'd have the timing belt off the pump to rotate the sprocket by hand to feel for any 'life' in it, usually you can feel it as they have a "springy" feel to them, if it spins freely then the drivedog has broken and its time for a replacement.

I thought about a failed solenoid but its very rare they fail closed if they are going to die they fail open in about 95% of the time. I think I've only ever seen one fail 'shut' compared to a few dozen that fail open.

I'd hold off for one of the others to post though, we have some highly skilled people here a lot higher than me at least ( ! ) for their thoughts.

[Peter.N.]

In addition to the above, try slackening off a couple of injector pipes, preferably on the injectors but if difficult the pump end will do, turn the engine over and see if you have any fuel coming out.

Peter

[bertiewhite]

Thanks for your replies - the van now lives!! There is a saying we use a lot at work, "Don't assume, check". I had to replace the solenoid a few weeks ago as the engine wouldn't cut off without me stalling it. Just to satisfy myself that I was actually getting fuel through the pump I decided to take the plunger out and refit the solenoid without it. At the same time I briefly clamped the return pipe (it's been replaced with a more pliable type of hose) which meant I was able to get the primer bulb to go stiffer and maybe move some air round the system. I've yet to fit the solenoid again to confirm if it is faulty but the van's running again now as if nothing's happened

At least I know my way round the fuel system now - it's my first diesel and I never realised what effect air would have on it.

[spider]

Excellent news.