Annoying fuel problem

[nexarius]

Hi,

I have a Xantia (97 1.9TD) which takes a hell of a long time to start if you leave it for more than a couple of days without using it. It also takes a long time if its hot and you've left it for a while.

I have replaced the starter motor and the leakoff pipes so far and the problem is still there. It turns over a hell of a lot faster now but still has to do so for ages before it gets any diesel.

When it does eventually start, it runs smoothly immediately on all 4 cylinders, so I'm ruling out glow plugs. I'm almost certain it's a lack of fuel problem.

If you prime it with the "grenade", it starts immediately, but the grenade requires something like 10-20 pumps before it 'hardens'.

Obviously there is something wrong, but what should I be looking for that would cause such a considerable amount of diesel to be returning to the tank.

Also, I don't hear any fuel pumps running when I turn on the ignition. Is this normal? (I'd expect a priming pump sound like on our petrol Xantia)

Cheers.

[CitroJim]

You definitely have an air leak between the tank and fuel pump causing this. Favourite spots are the primer bulb (love your term "grenade", describes it well!!!) and the fuel filter housing. It can crack. The problem in finding the leak is that the whole fuel delivery system in under "suck" so will never leak fuel, only draw in air. Substitution is the only sure way to find the culprit. A good way of diagnosing is to replace the pipe runs between priming bulb, filter and pump with clear plastic ones. In this way, you'll see the air bubbles and lack of them when you've found it. My money is on the priming bulb. Do check the seal between the lid and body of the fuel filter as well.

The situation is made worse by the fact that the pump to lift fuel from the tank to the injection pump is in the injection pump itself. There is no pump in the tank, only a strainer. Any air leaks on the fuel supply side means the lift pump has to drag fuel and air all the way from the tank before it is 100% clear of air.

[nexarius]

Hi 'citrojim',

Sadly I'm off to university without the car in a couple of days, so I cant do any more "real" investigation until December.

I should have pointed out, though, that there's a strange whistle emitted from the injection pump when the engine has just been shut off. The whistle stops if you squeeze the 'grenade', then starts again. It sounds to me like air escaping, but it doesn't do it for very long.

I really hope your diagnosis is correct. I'm dreading that it's the pump that's leaking!

Cheers.

[CitroJim]

That is an air leak on the pump. Check the banjo union in the left-hand near corner of the head where the fuel supply line enters. A lot of TDs had clear pastic fuel lines between the filter and pump and these, over the years, go very hard and brittle. I'd not be surprised if the leak was not at the junction of this pipe and the banjo on the pump.

A leaky pump will leak diesel as once past the lift pump, the diesel is under pressure within the body of the pump and at a sufficient pressure to cause a fuel leak from the tiniest of gaps.

All the best for forthcoming university

[nexarius]

Excuse my ignorance, but I'm not entirelly sure where the fuel goes in.

It looks to me like it goes from the grenade into a square vertical long thing that has the oil dipstick on it and also the brown coolant temperature sender.

From there it all goes a bit like spaghetti and that thing has so many pipes coming out of it....

there is a small amount of noticeably leaked diesel near the bit that turns when you pull the throttle. I hope that's not related.

[CitroJim]

The fuel line runs from the grenade to the filter and then, from the top of the filter to a banjo union on top of the injection pump. It is in the vicinity of the throttle lever.

If you look straight down on the pump top, look in the bottom left-hand corner (nearest the cambelt and hydraulic pump) and you'll see a 17mm thin hex bolt head. This holds the fuel inlet banjo to the pump body. Look back from the banjo and you'll see the supply pipe running back to a right-angle and then a straight run adjacent to the injectors before making two more right-angled bends to meet with the top of the fuel filter.

Diesel leaking on the top of the pump or the sides can be a bad sign and it can cause your problem as when the engine is off it can draw air. Favourite spots for leaks are on the throttle spindle (sealed by one O ring) and the pump lid to body joint which is sealed by a shaped plastic gasket. Replacing these is not a trivial job, especially on an armour-plated anti-tamper pump.

Hopefully, it's the inlet banjo or the pipe leaking and not the pump. Give it a very good clean using a slovent and watch carefully.