MatraSport Forum

Each model => Espace => Topic started by: Anders Dinsen on June 15, 2011, 06:13:33 pm

Title: Fuel leak from in-tank pump assembly
Post by: Anders Dinsen on June 15, 2011, 06:13:33 pm
I've got a fuel leak from the pump assembly. It looks like it's from the pressure side. I lowered the tank just enough to get a peek there and take the photos below. Does anyone have a similar experience? To me it looks like it's the connector which is somehow not sealing anymore. I'm going to call my parts dealer to get his opinion on this problem (he has probably seen it before) before I remove the tank completely to fix the problem.


Title: Re: Fuel leak from in-tank pump assembly
Post by: jack daniels on June 15, 2011, 08:56:22 pm
could this be a push on style connector similar to the fuel filter connections?
 from the photo it looked like an aprox 75mm dia. screw-on plastic cap holding the pump assembly that's sweating a bit, perhaps in the summer heat?  the fuel tank breather tube or cap is not blocked is it?

Title: Re: Fuel leak from in-tank pump assembly
Post by: Anders Dinsen on June 18, 2011, 08:24:07 pm
Roy also noted the seeping fuel from the cap and suggested that the o-ring gasket around the pump assembly could be damaged. This is not an uncommon problem.

However, he also suggested that the pump may not be running and that might be why the car is difficult to start - this indeed appears to be true. I checked (and replaced) the pump relay today and it is clicking as it should, but 9 of 10 times when ignition is turned on, the pump does not run. Cranking the engine appears to be enough to kick it to start, and then it keeps running.

So it seems I have two problems - the fuel leak AND a dying pump  :-\


Title: Re: Fuel leak from in-tank pump assembly
Post by: jack daniels on June 19, 2011, 09:54:18 pm
... so I guess you'll have to do some driving first to empty the tank and make it easier to lower.

277 euro for a new bosch pump apparantly

Title: Re: Fuel leak from in-tank pump assembly
Post by: on June 20, 2011, 09:18:05 am
It is a common problem indeed.
Had same problem. The pressure pipe from the top of the pump assembly was cracked a little. From here comes the leak. The black ring that holds the pump assembly on tank was cracked too.

You can see here how the pressure pipe can be repaired, there is another solution, on the forum, with brass and some special epoxy glue, but for some reason I can't find it today.
Last minute edit: I have browsing the link above, and I don't recommend this. The inner diameter of pipe is reduced, so the flow of fuel is reduced also. This repair might not be as good as it seems.
Anyway, in this link, you have pictures with faulty pressure pipe.
... and I have found it
another here

Mine have same "click" connectors. I don't think they are faulty.
Personally I bought a new pump assembly and replaced the cracked one. It was a bargain, aprox 100 euro. That was happened exactly in mid of june last year. I kept the old pump assembly.
The black plastic ring is the same on certain models of Twingo. The pump assembly was fitted by Matra/Renault only on JE and Avantime.

( (

The phenomenon is quite complex... or simple?!?!?! . Roy can correct me, or anybody if I'm wrong.
When Loosen the cap from the tank to refill with gasoline at gas station, a lot of air came out of the tank.

A question here: Those with petrol engines. Do you have the same experience?
From here starts my hypothesis.

So, the tank is expanded almost all time. There is little room between top of the pump assembly and metal chassis of the car (1-3 cm). When pump starts, the tank is inflated, and this space is reduced to zero. I think ?!?!  :-\
The "click" connector of pressure pipe is bulky, and is the first, who reach the metal floor of the car when tank is inflated, with the "help" of nervure. The tension is passed to the pressure pipe, which has no reinforcement.
The protective cover of the pump assembly is made from flexible plastic, and playing no role in protection of the pump assembly pipes. On the contrary the plastic nervure put a lot of pressure on the "click" connector.

Bad design ?

Again I'm not working for FBI  ::) and I'm not a mechanical engineer. This are my pure suppositions. Anyone can correct me.  :D

Title: Re: Fuel leak from in-tank pump assembly
Post by: jack daniels on June 20, 2011, 08:38:27 pm
your hypothesis could be correct.
I have not experienced built up pressure in my tank when I loosen the filler cap, as far as I know there's no leak or sweating either. I have heard of leaks in other brands of car because an after market fuel filler cap is fitted which probably is not vented well enough. I think most vented caps have a kind of filter sponge material in them which may get blocked over time. Plastic tanks can certainly swell but there shouldn't really be too much build up in there.

 Leaving the filler cap loose while driving and then looking to see if there is still as much leakage as before may reveal if pressure build up is contributing.

Title: Re: Fuel leak from in-tank pump assembly
Post by: on June 20, 2011, 11:09:16 pm
To be clear.
I have no leaks from june 2010, when I have changed the pump assembly and black plastic ring.

Just that hiss noise when open the filler cap.

I do not ever fill the tank. I put in it only 20-25 liters. I do not know if this helps or if that is the cause of hiss ?!?!?

Title: Re: Fuel leak from in-tank pump assembly
Post by: jack daniels on June 21, 2011, 08:11:59 pm
I guess the more air there is  in the tank, the more expansion when it warms up. I keep mine 50-100% full if possible.

Title: Re: Fuel leak from in-tank pump assembly
Post by: Anders Dinsen on June 22, 2011, 08:44:07 am
I have had some very busy days lately, so I didn't see your posts until this morning. - This is very useful information. I regret not being able to follow Espace-freunde forums, but thanks for communicating this. I agree with you that the repair does not look optimal - and that the design is also not perfect. I have ordered a new pump from Madcom on eBay, it was less than half price what I have to pay from Renault. I have also ordered a new gasket and lock ring for the top of the tank, though - just to be on the safe side.


I'll keep you posted when I get the repair done. Probably sometime next week. Meanwhile the car is smelling a bit and sometimes plays up on me.


Title: Re: Fuel leak from in-tank pump assembly
Post by: on June 22, 2011, 09:46:00 am
Stay calm, especially if you keep the car in the parking lot outside, away from any source of fire!  ;D

 I drove the bomb more than 2000 km, and nothing happened. This way I bought it in Germany, but I did not realize until after I filled the tank, and there was a "lake" of gasoline on the asphalt. There was no way back. There a repair would cost me too much for the budget at that time. So I drove 2000 km home. I do not know how much gasoline I lost.

I will not do that again, I promise!  ::)

Anyway exhaust pipes are far, electrical socket of the pump is safe.
But electrostatic energy could create problems.

@Jack Daniels
Now begin to make sense. Thanks. I'll fill the tank and see.


Title: Re: Fuel leak from in-tank pump assembly
Post by: Anders Dinsen on June 23, 2011, 06:22:49 am
I'm not worried - petrol is actually not easily ignitable, only petrol fumes are. Even a large leak is not likely to cause a fire. And the leak on my car is very small, e.g. nothing is visible under the car, only the smell of petrol. A petrol explosion can only happen if there is air and petrol fumes in a container - like in a cylinder. The leak outside the tank is not dangerous.

It broke down on the way to Le Mans two weeks ago, so I've also done more than 2000 km with the leak  ;) I checked fuel consumption on the way - it was normal, so the leak is indeed very small.

And a new pump, seal and locking ring is on the way :)


Title: Re: Fuel leak from in-tank pump assembly
Post by: Anders Dinsen on July 15, 2011, 09:17:24 pm
I completed the fuel pump replacement last Sunday. The working position under the car is pretty awkward. If you need to do this job, I highly recommend you empty the tank completely as just 10 litres of fuel makes it pretty hard to manage without spilling fuel out of the inlet  ::)

To start with conclusion, the problem was correctly diagnosed by The outlet had cracked off the fuel pump assembly.   :-\

The stud broke off completely when I tried pulling the fuel hose off it, so I couldn't directly inspect the crack, but the black dirt markings on this photo of the stud shows how large it actually was:


Roy had suggested that the locking ring and the o-ring seal under between the pump assembly and the tank might have been damaged, so I had ordered new ones in case they were.

The ring was very difficult to remove eventually it split. With a new ring at hand this didn't worry me, but unfortunately, the new ring did not fit at all! The workshop manual warns that the tank should not be left without the ring for more than a short time or the opening can be distorted. I don't know if this was what had happened, but there was no way the new ring would fit  :-\

So I ended up reusing the old ring and fit a steel band around it to keep it tight. With the band on, I was able to tighten the old ring well over the pump, and I expect this work fine. I fitted the new o-ring seal of course. The old one appeared to be ok, but it had increased slightly in diameter indicating that replacing it was a good idea.


So the fuel leak is gone and the starting problem is completely cured now too. I'm actually quite impressed that the car ran as well as it did with the leak. The fuel pressure must have been far too low  ???

I have thought a bit about why the stud broke off. Is it really a design fault? Obvioulsy, the plastic stud can't take as much stress as a steel component, and the plastic seems to be pretty cheap, so the quality could certainly have been better. But this is a typical pump assembly for modern cars. And I couldn't see any indications that the stud would have been under any kind of pressure from the chassis and the cover over the pump. So what caused it to break? Vibrations? I think so, yes: If something is vibrating and pulling the fuel line, the stud may end up breaking. Note that the fuel lines aren't made of rubber. They are made of plastic and are quite inflexible.

And I think I know what caused it: If you take a look at this photo, you'll see that the fuel filter bracket on my car is actually broken and that my mechanic has used a cable tie to fit the filter to the tank. Note that since the filter is full of fuel, it's quite heav. Unless the filter is suspended correctly on the tank, vibrations will work through the fuel line and to the stud, eventually breaking it. I'm going to replace the bracket as soon as possible, of course!



Title: Re: Fuel leak from in-tank pump assembly
Post by: Alfistipohjoosesta on October 23, 2011, 06:32:19 pm
My Espace leak just same place. I drill hole, pump assembly, and remove plastic what on way. Modify copper pipe 90 decree curve. Inside is pump assembly what is rubber hose. I connector pipe in hose. Clue copper Plastic Paddin Leak clue in pump assembly cover. Remove plastic hose and use rubber hose in fuel filtter.  Works and not leak in 2 years. Cost 15e clue, hose ecs..