Petrol tank (small loss of fuel)

H

H3nrY

Well-Known Forum User
Hey all

I have a problem with my petrol tank. I took it out 2 weeks ago because of the sender unit not working properly. After reinstallation, I let it run for a couple of minutes, all seemed ok.

Now after a drive and hitting the accel pedal, I noticed that the right-bottom of the tank, and the right rears showed a small film of petrol. I used a new joint for the tank plug on the bottom. I checked the filler hose strapper and it seemed ok. The only thing I can think of is the sender unit itself. I took it out and reinstalled it, carefully placing the O-ring back to its place. But I still get that small film of petrol.. any ideas ?

I´m going to england in a few weeks time, and I do want this to be in order before setting off. Regards hendrik
 
Have you got under the car to see if you can pinpoint the souce? Check the fuel inlet and outlet pipes on the tank, leak could be coming from the base of one of those pipes or from a fuel clip not being on tight enough.
 
Mr.G said:
Have you got under the car to see if you can pinpoint the souce? Check the fuel inlet and outlet pipes on the tank, leak could be coming from the base of one of those pipes or from a fuel clip not being on tight enough.
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Hey Mr. G, thanks for the quick answer. I checked the inlet and outles nozzles and those are dry. I think it must have something to do with the sender unit. I first put the O-ring around the ring of the gastank, then the sender unit, and then the retaining clip. Maybe the O-ring did not stay in place
 
try using some sort of putty to pack in that small gap around the sender unit. See if the leak stops then. It's a bodge but may work.
 
What about the breather pipe at the top rear of the tank. It comes through a tube into the boot behind the rear trim panel.

Mine leaked there when I bought it. It's a tank out job though.
 
Rob Gaskin said:
What about the breather pipe at the top rear of the tank. It comes through a tube into the boot behind the rear trim panel.

Mine leaked there when I bought it. It's a tank out job though.
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Rob

Yes, I checked the 2 hoses behind the rear trim, seemed dry and clean. Ill try mattbibbey´s idea of using some tec7 around the sender unit gap and see if it stops.
 
I think that Matt has got the problem identified, Hendrik, but be careful what type of sealant you use to re-make the O-ring seal. It needs to be petrol resistant, which none of the Silicon based stuff is.

The only thing that will do the job that we are aware of is called Dirko - it's what BMW & Mercedes use in Engine assembly for minor water & oil outlets such as the Thermostat Housings, etc.
You might need to go to an Engine or Machine Shop to buy some - unles you can find an alternative make that states clearly that it is resistant to Petrol.
Also try to get a new O-ring from MJP before you try again, and clean up the faces of the metal clip & the face of the Fuel Tank itself - both need to be perfectly flat to get a good seal.
 
Hey Duncan,

Yes, I´ll ask a local garage if I can lend some of the stuff. I´ll put it around the hole where the O-ring goes and hope it keeps the petrol from coming out.

Also, I get a readout now from the sender on the dash, but it´s reading upside down. So its nearly full, but Im getting nearly empty. I already switched the position of the sender unit, but it remaines the same. Could the unit be broken?
 
Have you swaped the wires on the sender round? If you have and it still doesnt work then try removing the complete sender unit and inverting it - you may have the arm the wrong way around. A pain if you have it completely full with fuel as you will have to drain.
 
Mr.G said:
Have you swaped the wires on the sender round? If you have and it still doesnt work then try removing the complete sender unit and inverting it - you may have the arm the wrong way around. A pain if you have it completely full with fuel as you will have to drain.
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Good call, call me stupid, but didnt check on that ! I´ll give it go and see if it helps. As for draining..(i love the smell of petrol^^)
 
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