S1 1.9TD Bosch Fuel Pump

Unread post by **Old-Guy** » 15 Nov 2010, 10:40

One for injector pump experts please.

Basic problem is fuel draining back into the tank from the engine. Aggravated by the car living on a sloping drive facing up-hill and often not used for days on end. This has gradually got worse in the 3½ years I've had the car.

Symptoms. More churning than should be necessary is needed when the car has been left (hot or cold). Does start instantly (hot or cold) if stalled or only left off for a few minutes. If fuel is pumped up manually, starts immediately even when left for some days. When pumping manually, I can feel when all the air has been expelled, but I can still squeeze fuel through. Even after I've got the fuel system well pressurised manually, I can't see a fuel leak anywhere.

The fuel filter element and seal has been replaced several times (services) and the housing cover has also been replaced (I snapped the outlet pipe off!).

The remaining leak-off pipes look good (I've replaced the more accessible ones including the blind end) as I had the kit. The two awkward ones look in good nick and show no signs of leaking.

Short of a complete pump rebuild with all new seals, are there any favourite places to look?

spider · Unread post by **spider** » 15 Nov 2010, 10:52

Inspect joins anywhere in fuel system (feed really mainly) , it could be anywhere that is taking air in.

Be aware it will probably not leak fuel out unless it is bad.

As a temporary 'fix' , consider this: obtain a non return valve or two and fit one just before the fuel filter and one just before the pump. I have done this to my 205 while attending to other issues and it fixed it, although I did change the main fuel pipes a while after that anyway.

You can get them from ebay, I do not think they were more than about £5 each.

The reason for two is the one before the filer will stop anything draining back towards the tank and the one just before the pump will ensure that anything cannot drain back out of the pump.

Xantidote · Unread post by **Xantidote** » 15 Nov 2010, 11:31

Many years ago, articles in the Diesel Car magasin recommended smearing grease over the joints in the feed lines, to locate the culprit, though I never tried this myself.

As well as checking the joints, it may be worth a close visual inspection, to check for old rubber perishing, including the squeeze bulb (which I assume you have) in the feed line. At least you know what the problem is, and know how to get round the problem to get the engine started

spider · Unread post by **spider** » 15 Nov 2010, 12:16

Grease does work yes, usually

The favourite is the primer bulb in most cases. I ended up (having a different layout) wrapping my filter assembly in a couple of tightly cable tied plastic bags, which improved the situation so I knew the filter head was the main problem in my case (but not your's as you will not have that type of housing) , still the grease principle applies.

The other one is the lines where they join the pipes under the car (either front or back) or less common at the fuel tank pickup point.

stevemc · Unread post by **stevemc** » 15 Nov 2010, 12:42

have you checked the fuel tank vent ,if thats blocked it causes the fuel to be sucked back into the tank

Unread post by **citroenxm** » 15 Nov 2010, 12:57

Fuel Return pipe or feed pipe down the back of the engine were it Curves!

Constant engine movment can cause these to split and let air in to drain..

Paul

Unread post by **Peter.N.** » 15 Nov 2010, 18:40

Leakage at the injector leak off pipes can also cause this problem. If you park your car facing down the slope you will probably see fuel leaking out.

Peter

Unread post by **Dommo** » 15 Nov 2010, 20:04

I had this problem last week, sorted by fitting a new priming bulb and the fuel line between the primer and the fuel filter housing.

spider · Unread post by **spider** » 15 Nov 2010, 20:07

stevemc wrote:have you checked the fuel tank vent ,if thats blocked it causes the fuel to be sucked back into the tank

I have heard of cases of the pump actually imploding (ie: sucking in) a plastic tank a bit due to pressure, although I've never seen this happen. Not sure what PSA vehicle though.

Unread post by **Old-Guy** » 16 Nov 2010, 16:15

Thanks everyone for all the suggestions. I forgot to say that a couple of months ago, an additional non-return valve was fitted in place of the standard plastic joiner between bulb and filter.

As even extended pressurising with the bulb won't persuade fuel to weep out anywhere (upstream of the injector pump), I guess it has to be air getting in from the leak-off pipes that allows the pump to drain down.

The weather forecast promises heavy rain tonight so I'll have to wait for the next dry night to park the car nose down - otherwise there's risk of soggy carpets.

It may be better to bite the bullet and replace the remaining leak-off pipes - that will at least eliminate this possibility.

spider · Unread post by **spider** » 16 Nov 2010, 16:27

Last time I purchased any leak off pipe, It came from the dealer (it was not expensive actually) and was just a length, plenty enough for the bit between the injectors and the return piece too.

EDIT... Don't overlook the 'cap' either on the end injector