Fuel tank leak

One anomaly is the fuel gauges. I’ve never ever trusted them, but he said it should have registered some loss (in fact it actually shows more fuel in it than a month ago!)
Can you not dip the tank with a length of wood dowel and mark it, will be more accurate than fuel guages for seeing if the level drops.
 
Can you not dip the tank with a length of wood dowel and mark it, will be more accurate than fuel guages for seeing if the level drops.
I did already with a retractable steel tape measure, but it involves removing the sender unit, which takes half an hour !
 
I’m hoping (against hope) that it’s not the tank.....
Oh I'm sorry. I thought the thread title was "Fuel tank leak" and you have, I think, shut off the cock on the tank, and the amount leaked is more than would be accounted for by a leak from the piping and pumps. Or have I misread you?
 
I'm with kashurst here.
There is little point in "just monitoring" the leak.
You HAVE to isolate the tank completely and remove everything else.
Then, if it still leaks it has to be the tank.
Like everything that you diagnose, work your way back into the problem.
There's no point in just looking at it.
 
I'm with kashurst here.
There is little point in "just monitoring" the leak.
You HAVE to isolate the tank completely and remove everything else.
Then, if it still leaks it has to be the tank.
Like everything that you diagnose, work your way back into the problem.
There's no point in just looking at it.
No, that’s what I am going to do. I’ve been a little distracted assembling my car port.....?
 
I’m pumping out half a liter a day, consistently. In total I would guess 70 + liters. The fuel lines would hold a couple of cupfuls, I’d guess. And the engine and generator fuel filters are still full of fuel. With the tank stopcocks shut, I’m guessing that the fuel in the fuel lines and engine / generator has not lost a drop.
But it’s all speculation
7à litres is not coming from anywhere but the tank, if you had 70 litres in the bilge it would have stunk to high heaven plus it's appearing gradually and consistently that doesn't equate to coming from the bilge, far more more likely a leak, it's just a question of where. Are there any hidden connections?
 
Oh I'm sorry. I thought the thread title was "Fuel tank leak" and you have, I think, shut off the cock on the tank, and the amount leaked is more than would be accounted for by a leak from the piping and pumps. Or have I misread you?
Yes, a suspected tank leak......but a lot of people here say there is still a chance that it’s not...??????????
 
7à litres is not coming from anywhere but the tank, if you had 70 litres in the bilge it would have stunk to high heaven plus it's appearing gradually and consistently that doesn't equate to coming from the bilge, far more more likely a leak, it's just a question of where. Are there any hidden connections?
I will do what I can diagnostic wise, and can only hope for the best and save up for the worst. As for hidden connections, it’s all hidden, that is my problem. I can only see the top and front of the tank, that leaves four sides completely obscured.
The mechanic was looking for a way the fuel could get under the liner, he had his office send him photos of all the drain holes in the liner, none appeared to be in the right place to catch the oil and divert it. Just part of the mystery
 
I will do what I can diagnostic wise, and can only hope for the best and save up for the worst. As for hidden connections, it’s all hidden, that is my problem. I can only see the top and front of the tank, that leaves four sides completely obscured.
The mechanic was looking for a way the fuel could get under the liner, he had his office send him photos of all the drain holes in the liner, none appeared to be in the right place to catch the oil and divert it. Just part of the mystery
Perhaps a Depstech endoscope might be useful to you.

Only £37 from Amazon.

I have one and it is very good.
 
I'm with kashurst here.
There is little point in "just monitoring" the leak.
You HAVE to isolate the tank completely and remove everything else.
Then, if it still leaks it has to be the tank.
Like everything that you diagnose, work your way back into the problem.
There's no point in just looking at it.
Absolutely, it's the first step before checking the filler hose, spending time removing the sender, adding UV dye, pressure testing, dipping and so on.

I've said it before, if the leak stops once isolated then add some more fuel. If it doesn't start again then the tank isn't leaking but if it does leak again then it had simply reached the level of the leak in the tank.

The tank is the only large source of diesel and removing the hoses is a really simple job. Just seal all ends after disconnecting.

A hidden connection is possible but unlikely. All the outlets I've seen enter near the top of a tank. Drilling holes in the bottom isn't a great idea. The only things I've seen on the base of a tank have been welded sumps with drain points and they've always had a plug, not just a drain valve.

Simple step by step diagnosis of a fault, not just randomly checking things in the hope you will find something.
 
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