Citroen ZX 1.9TD - need to prime fuel before starting

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Thu 20 May 2010 17:25
Citroen ZX 1.9TD - need to prime fuel before starting - eldublu

Had this problem a while. So far have changed all pipework in engine bay, leak off pipes, priming bulb and O rings on fuel filter housing. Even so, after about 4-5 hours standing it needs to be primed before it will start. When priming I can hear the fuel filter housing refilling with diesel. Can anyone give me any pointers on this one?

Cheers

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Thu 20 May 2010 17:33
Citroen ZX 1.9TD - need to prime fuel before starting - Peter.N.

Mmm, if its a Bosch pump I would have said leak off pipes. It doesn't have a fuel heater on the end of the head does it? The XM with the 2.1 XUD does and it goes pourous, most of them have been bypassed by now. The only thing I can suggest is that you pump hard and keep the pressure up for a few minutes and watch for leaks, alternativly, park it on a steep downward slope so the tank is above the engine and again, watch for leaks.

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Thu 20 May 2010 18:53
Citroen ZX 1.9TD - need to prime fuel before starting - eldublu

Cheers Peter.

There is a heater on the head, when you say bypass do you mean fitting an aftermarket filter housing. If so, how is the fuel warmed?

I've been out and carried on priming, there is some fuel leaking past the no4 cylinder leak off connection (where the rubber bung blocks the final connector). As this is blanked off I would have thought this was likely to happen once the pressure in the fuel lines got high enough, or am I way off the mark (not the first time)?

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Sun 31 Oct 2010 13:25
Citroen ZX 1.9TD - need to prime fuel before starting - koootzz
Ok, I have been making do with this problem for some time hoping that the cause of the problem would get worse and show some evidence. It looks like this is the case now. On the furthest injector from the pump there appears to evidence of diesel leaking, at the moment I can't tell if this is from the blanking plug on the leak off or from the injector itself. Couple of questions...
Is it common for diesel to force past the blanking plug, can this be caused by a faulty injector?
If not the injector, is there a fix to stop this happening ( apart from another new blanking plug)?

Thanks
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Sun 31 Oct 2010 14:01
Citroen ZX 1.9TD - need to prime fuel before starting - Collos25

Diesel leaking from an injector will not stop it starting,If you have no visible leaks then more than certain you have a problem with the pump it needs removing and testing on a proper pressure measuring equipment.Until you have aleviated this as problem you cannot move forward.

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Sun 31 Oct 2010 14:13
Citroen ZX 1.9TD - need to prime fuel before starting - Peter.N.

Leakage from the injector leak off's will indeed cause air ingress on the Bosch system, as in their wisdom they have connected it to the flow rather than return pipe. If you have a fuel leak when running this can turn in to an air leak when stationary.

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Sun 31 Oct 2010 14:21
Citroen ZX 1.9TD - need to prime fuel before starting - Collos25

But not stop it starting.

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Sun 31 Oct 2010 14:30
Citroen ZX 1.9TD - need to prime fuel before starting - tdc

Does your car ever stop or falter when you are driving?

My trusty old BX 1.9td only let me down on one day and that was during a rush-hour drive through the centre of Leicester,conking out several times including at the head of traffic-light queues!Each time I lifted the bonnet and bled the system.When I got home(eventually)I took it upon myself to replace all rubber fuel lines between engine bay and fuel tank.Following that it never faltered again in my remaining two years of ownership.

Must have been a pin-prick of a hole(that`s all it takes) somewhere in one of the hoses but never did find it...no leaking fuel,just obviously drawing in air.

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Sun 31 Oct 2010 15:10
Citroen ZX 1.9TD - need to prime fuel before starting - koootzz

Thanks for the quick replies.

The car never misses a beat once it is running and will always start easily once the system has been primed, but it will chug for a second or so once started.

So, if the Bosch leak off pipes are fed back to the flow side when the engine stops this air ingress will allow the diesel to be drawn back towards the tank?

The leak off pipes and blanking plugs were replaced earlier in the year, after closer inspection there is a black gum around the port that the blanking plug attaches to so the plug has been/is obviously leaking but there is also fresh diesel around the injector itself so maybe this has developed a leak too. Time for a new injector? Is there a way to seal the blanking plug to elimate that first (don't think I can get a jubilee clip small enough).

Cheers

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Sun 31 Oct 2010 20:08
Citroen ZX 1.9TD - need to prime fuel before starting - Gregory II
"most of them have been bypassed by now"
Can someone clarify as to what is meant by bypassing? I have wondered about this and why this has been done. I presume it is related to starting problems?
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Sun 31 Oct 2010 20:41
Citroen ZX 1.9TD - need to prime fuel before starting - Peter.N.

Probably referring to the fuel heater on the gearbox end of the cylinder head, if yours has one that could be the problem, just remove the pipes and join them together, or you may find that one is long enough to reach the filter. Yes, if air leaks into the injector leak off circuit it will allow the fuel to drain back to the tank - as will a leaky fuel heater.

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Sun 31 Oct 2010 23:01
Citroen ZX 1.9TD - need to prime fuel before starting - 659FBE
Vehicles fitted with Bosch VE rotary pumps have the injector leakoff pipes connected to the fuel return and not to the flow.

Leakage at this point is critical and will prevent the engine from starting because air introduced at this point allows the rest of the LP fuel system to drain back into the tank by venting it. When the system is operating correctly, the entire pump remains full of fuel (and the transfer pump within it fully primed) allowing good starting.

The LP fuel hose used by PSA at that time becomes hard and brittle with age, leading to leaks after many years of engine vibration and thermal cycling. As these engines usually last well, the fault shows before the vehicle is scrapped.

All LP hoses are suspect, including the cap on the end injector leakoff nipple.

659.
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Mon 1 Nov 2010 21:22
Citroen ZX 1.9TD - need to prime fuel before starting - tdc

Following on from the excellent advice above,if you find yourself without a clip small enough to secure the leak-back pipes in place?......what I`ve done many a time is snipped a piece off my roll of thin stainless-steel locking wire,wrapped it around pipe twice and tightened.Obviously don`t overdo it or else you`ll cut through the pipe!

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