General Fuel leak

[tobywood13]

1993 Panda 1000, single point injection model, plastic fuel tank.

Hello all, I just filled up my Panda to the brim and came back after paying to see a significant puddle and a lot of dripping underneath the tank, I'd estimate two or three pints' worth ended up on the floor. The filler neck was dry along with where the neck joins to the tank. The drips were collecting at the lowest point of the tank with moisture all over the sides, seemingly the moisture coming mostly from towards the front of the car. I waited a few minutes until it stopped dripping, hosed the underside of the car off, then drove a few miles home without any incident. When I got home the tank hadn't leaked any more, there was petrol moisture underneath but not very much. It seemed to happen only when I brimmed it. Do Panda tanks have an overflow/purge valve in case of over-filling perhaps?

The fuel gauge on the drive back showed full or ever so slightly under full, so it isn't losing much fuel. This suggests the hole is somewhere at the top of the tank.

Are there common failure points to check? The fact it wasn't soaking wet after driving it a bit rules out the fuel lines, in my head at least. To me, it seems most likely that there is a split in the fuel tank near the top somewhere, and filling it all the way up caused the leak. If anyone has any further advice, I'd greatly appreciate suggestions! Also, if anyone knows where I can source a new tank for a 2WD Panda, that would also be helpful. Thanks!

 

[tobywood13]

I think I’ve located the source of the leak, it’s a hose on top of the tank. This is the only thing I can see that appears wet still, besides the residue at the very bottom.

Attached photo is looking from the left hand side (passenger/near side), just in front of the rear wheel. The hose runs over the top of the fuel tank, and is pressed up against the body work.

Why would this leak when filling up? Is this how it is supposed to be routed? It seems like it shouldn’t be squeezed between the tank and the body. Perhaps that has worn a hole in it.

 

[bugsymike]

1993 Panda 1000, single point injection model, plastic fuel tank.

Hello all, I just filled up my Panda to the brim and came back after paying to see a significant puddle and a lot of dripping underneath the tank, I'd estimate two or three pints' worth ended up on the floor. The filler neck was dry along with where the neck joins to the tank. The drips were collecting at the lowest point of the tank with moisture all over the sides, seemingly the moisture coming mostly from towards the front of the car. I waited a few minutes until it stopped dripping, hosed the underside of the car off, then drove a few miles home without any incident. When I got home the tank hadn't leaked any more, there was petrol moisture underneath but not very much. It seemed to happen only when I brimmed it. Do Panda tanks have an overflow/purge valve in case of over-filling perhaps?

The fuel gauge on the drive back showed full or ever so slightly under full, so it isn't losing much fuel. This suggests the hole is somewhere at the top of the tank.

Are there common failure points to check? The fact it wasn't soaking wet after driving it a bit rules out the fuel lines, in my head at least. To me, it seems most likely that there is a split in the fuel tank near the top somewhere, and filling it all the way up caused the leak. If anyone has any further advice, I'd greatly appreciate suggestions! Also, if anyone knows where I can source a new tank for a 2WD Panda, that would also be helpful. Thanks!

It may be the tank sender/pump unit seal at top of tank.
Often a cover screwed down under the rear seats will give access to it.
Plastic tanks themselves are usually trouble free.

 

[tobywood13]

Comparing my earlier photo to this diagram I found, is the circled bit the likely culprit? If so, how do I replace that hose only?

 

[tobywood13]

Comparing my earlier photo to this diagram I found, is the circled bit the likely culprit? If so, how do I replace that hose only?

Nope, these seem to be electrical wires. I’ve had the car running, been crawling around underneath it and can’t see any sign of leaks. Must just be when the car is filled. Any suggestions why it might be leaking when filled up, but not while running?

 

[bugsymike]

Nope, these seem to be electrical wires. I’ve had the car running, been crawling around underneath it and can’t see any sign of leaks. Must just be when the car is filled. Any suggestions why it might be leaking when filled up, but not while running?

Over the years I have seen fuel leaking from any places, the filler pipe whether metal or plastic, the breather pipe, some have metal pipes across the top of tank that are part of the metal tank on some Japanese vehicles, metal tanks that have rusted.etc.
However the most common with plastic tanks is often where the fuel sender unit sits in top of tank, so I would double check around there. Maybe get a fuel can and slowly fill up to where it started leaking before and check the areas I mentioned as level rises.
Beware of fire risks whilst testing.

 

[tobywood13]

Late update; finally got round to taking the rear seats out, opened the access flap, and filled up while looking in the back window to see it there were any leaks. Sure enough, the seal around the fuel sender is completely gone and a torrent of fuel came out the top before the pump clicked off.

I took the sender out and the seal was basically jelly. New seal ordered, hopefully that cures it.

 

[bugsymike]

I wonder if it is anything to do with E5 or E10 fuel, they say E10 affects older fuel systems.

 

[Dragon Man]

interesting.. i mean E5 will kill the seals too as it still contains ethanol. i have been running E10 in Talon well for years. no damage yet. besides already replace ebay fuel lines already cracking and replaced... again! (nylon pipe this time, lets see it eat through that!)
this gives me an idea...

 

[tobywood13]

Has anyone got the part number for the seal on the fuel sender? I ordered one from eBay that supposedly fit, but it was much too large (see picture).

 

[bugsymike]

Has anyone got the part number for the seal on the fuel sender? I ordered one from eBay that supposedly fit, but it was much too large (see picture). View attachment 462363

Totally wrong, did eBay photo show screw holes?

 

[porta]

That looks like the seal for the bolt down sender unit…yours is the later screw cap…if it helps they were common sizes across the range

 

[tobywood13]

I’ve managed to work out the part number using EPER, I think. 5888936.

Now, to track down one of these seals… might try my local FIAT dealer again.

 

[porta]

Failing that, which, knowing fiat dealers they will fail, measure the internal and external diameters and match them up on an internet search…there’s many a manufacturer car and parts, that shared seals and components, I seam to remember Renault, Peugeot, Citroen were vey similar

 

[tobywood13]

I’ve got a new seal, but now I can’t get the sender to sit properly! Is it as simple as putting the sender in and rotating clockwise a bit?

First photo is before I touched anything. The FIAT logo on the sender is in line with the ‘east-west’ axis. The second photo is with the new seal, taken upside down. I cant get it turn any further clockwise so that the logo lines up again. I think this is just because the new seal makes everything much tighter, but I don’t want to break any of the little plastic bits which I’m putting all my weight against. Any tips on how to get this to rotate a bit more?

 

[Dragon Man]

i cant say for fuel senders but i have had simular problems. usually its down to the new rubber seal being very.. grippy. try sticking a bit of engine oil on it both sides of the seal. it should really help when turning it into position.

 

[tobywood13]

i cant say for fuel senders but i have had simular problems. usually its down to the new rubber seal being very.. grippy. try sticking a bit of engine oil on it both sides of the seal. it should really help when turning it into position.

Good idea, I’ll try that tomorrow.

 

[tobywood13]

Well, I had a go at oiling the seal just now. Annoyingly it seems to have grown overnight. It’s no longer tightly attached to the fuel sender, and when placed on top of the tank there’s a good amount of excess poking out the side. Are these seals designed to expand when in contact with fuel?

The oil didn’t make a difference to my ability to turn the sender but I have a bigger issue now.

 

[ZaphodB]

Remove , and check size and shape is still original, check both mating surfaces for smoothness

 

[tobywood13]

Remove , and check size and shape is still original, check both mating surfaces for smoothness

Yesterday the new seal fit perfectly around the sender, today it’s stretched out. I cleaned up both surfaces yesterday and didn’t have any luck.