1990 cabby fuel leak

I just filled up my 1990 cabby with petrol, when I got home I noticed petrol was leaking on the floor at the rear of the car. So I rushed to put the car on the drive to jack it up to find the leak had stopped before I could get it in the air. Now there is no sign it even leaked but it left quite a large puddle where it was parked before putting it on the drive. I don't usually fill it up so this could have been an issue for quite a while.

Thoughts please

My 85 cabby was similar and was corroded fuel lines
Could be that once line gets de-pressurized due to leak the leak stops
Try turning on ignition on to check lines under fuel pump pressure

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The leak was coming from the very back of the car by the fuel tank. I turned the car back on after I put on the drive and pulled the choke out for a bit to raise the revs up but still nothing.

I had a similar problem with my 89 cabriolet, whenever I filled the fuel tank fully it would sporadically leak. It turned out to be the fuel sender. 

I had a similar problem this year with my 1.8GTI tintop and it was the gravity valve sticking causing the tank to pressurise. I was also getting a big whoosh of air when I removed the petrol cap. The pressure was causing fuel to be forced through the gravity valve and out through the trumpet looking breather that is attatched to the rear of the tank.

So today the leak got really bad same as before when the car wasn't moving the leak stopped. I jacked the car up to have a look and as soon as the car was tilted it started raining petrol. Looked like it was coming from the top of the petrol tank, can kind of see it in the pic

From the angle of the pic it's hard to tell where the fuel is coming from but the trumpet vent thingy is around that area. If you can get on your back righ under the car and look up you should see it. If it's coming from the vent then it's a breather issue, if not then it sounds like your tank is. I would definitely check your breathers first anyway as it's quite easy to do. The gravity valve is up by the filler neck and you have a pipe from the tank and a pipe to the trumpet thing. Check you can blow through both pipes and with the valve you should be able from the trumpet easily to allow air in as you use fuel but if you try to blow into the pipe from the tank you should have some resistance but still be able to blow through it. If the valve is upside down it should be blocked both ways.
Hope this helps.

The trumpet valve thing is on the other side of the tank. I did do a video and it was dripping from multiple places right up the top of the tank. I originally thought it was the filler neck but that is on the other side of the tank as well.
So it looks like I need a new tank then, anybody know how difficult this is to change over. I really want to do all the work on this car myself.
While I'm at it I might as well get all the new parts powder coated  

I fitted a new tank last year on my tintop and it's not a bad job to do but unless you have access to a ramp it's awkward as you have to do it all led on your back!
You have to drop the rear axle, watch you don't snap the bolts. You have to remove the brake flexi hoses to do this as well. I left my handbrake cables connected as didn't need to take the axle right out. Exhaust back box needs to come off. Disconnect the wires to the sender etc under the rear seat. Fuel pump etc needs to be disconnected (if it's fuel injected) drain the tank and undo the straps.
Allow at least a day, it might be worth cleaning backthe underside above the tank and treating it with something.

clean threads of axle bolts with wire brush, spray with pb-blaster   a couple days prior  air impact willlessen chance of shearing studs

I doubt it is the tank leaking from the top, more likely would be the sender unit o ring seal is leaking, it can be checked through the access panel under the rear seat

sporttrucker said

I doubt it is the tank leaking from the top, more likely would be the sender unit o ring seal is leaking, it can be checked through the access panel under the rear seat

I agree, take the base of the back seat out, undo the 3 screws holding the black cover on and remove, you will be able to see the top of the fuel tank, check for any leaks and check the rubber fuel lines.
Check simple things 1st before pulling out the fuel tank.

mark1gls said

sporttrucker said

I doubt it is the tank leaking from the top, more likely would be the sender unit o ring seal is leaking, it can be checked through the access panel under the rear seat

I agree, take the base of the back seat out, undo the 3 screws holding the black cover on and remove, you will be able to see the top of the fuel tank, check for any leaks and check the rubber fuel lines.
Check simple things 1st before pulling out the fuel tank.

I have to agree as well that it’s unlikely to leak from the top although I’d have thought the dripping fuel would be less localised if it was the sender. I would definitely check the sender seal first before dropping the tank.


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I will most definitely be checking this tomorrow. I'm glad I read this as I was about to place an order for all new fuel system  

Ok so I have just had a look through the inspection hole under the back seat. The top of tank looked dry but could really smell the petrol (it's been a week since it has last been used so might have dried up). I have a feeling the seal is knackered what do you think?

It looks like the seal is protruding in one place. Have you removed the sender to see what it looks like? I can’t imagine a seal being expensive so it would be worth replacing it anyway if it’s suspect.


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I haven't taken out the sender yet as I couldn't figure out how to take it out   I had the fuel tank cleaned out when I 1st got the car a year and half ago do you think the seal jus didn't go back in properly? I can get a new seal for £4.50 so will replace anyway

Yes you can see the seal sticking out so it may just be the seal needs replacing.
Unfortunately you have the plastic type sender which can be tricky to remove as you can't hit it with a bit of metal and a hammer. You need to make some sort of cross shaped key to fit into the 4 cut out, I've seen some made from wood, it's so you can turn the sender as it's like a bayonet fitting so only need to turn about 30 degrees to be lose.

They other problem you have is someone has used the wrong type of jubilee clip as it's best to use fuel hose jubilee clips as they squash the rubber hose all the way around when tightened them up, jubilee clips just tighten in 1 place. I would get 2 clips and replace both as the other clip is a use once clip and one it's removed it's scrap.

To remove the sender remove electrical connector, remove fuel hose but have the windows open and a cloth handy has petrol will come out, be very careful  not to lose the hoses or connector down the hole by the tank as it's a nightmare to get them out again and worse case is remove the fuel tank to get to them!

Is this the type of clip I should be getting and would you recommend me jus replacing the fuel sender unit?

No clips like this as you reuse them, ones in your link are again use once clips.

Shop around as 1st link I found. Most motor factors will sell them or you can pay over the top prices at Halfords if you don't have a local independent motor factors.   http://www.ebay.co.uk/itm/ASH-W4-Stainless-Steel-Mini-Metal-Nut-Bolt-Fuel-Hose-Clips-Petrol-Pipe-Clamps/201979592601?_trkparms=aid%3D555019%26algo%3DPL.BANDIT%26ao%3D1%26asc%3D20151016114640%26meid%3D7254bb073b084a688626a594e9662cf2%26pid%3D100507%26rk%3D1%26rkt%3D1%26&_trksid=p2045573.c100507.m3226

I would keep your fuel sender as they are expensive just be carful twisting it as the plastic can break.

I cant find an image but even a U shaped bit of wood may work, they are not that tight once they start to move, worse case but you may break bits of plastic is use a hard bit of wood and hammer to turn the sender but not the best way.
A bit like fig 8 in this link..
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