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-   -   On pressurizing fuel tank to find leaks. (http://www.peachparts.com/shopforum/diesel-discussion/408953-pressurizing-fuel-tank-find-leaks.html)

Shern 11-02-2020 10:59 AM
On pressurizing fuel tank to find leaks.
 
I suspect I have a pinhole leak somewhere in the fuel hard lines. Intend to unbolt them and check under the rubber but if it's a true pinhole, I don't suspect I'll see anything.

Remember reading someone suggesting pumping air into the tank.
I imagine clamping off the vent, the intake line and connecting the return line to a pump would be sufficient. What's a safe PSI to reach?

Or is this a bad idea in general?


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Jarod 11-02-2020 11:48 AM
I have heard the outlet from a wet dry vac directed into the fuel filler is enough pressure but won't damage anything.

I would hesitate to put a lot of pressure, but anything under about 5psi would be safe I think, as the aluminum pontoons on boats I work on tend to be pressurized to around 3-4psi for leak testing.

Hopefully someone with more experience chimes in, I'm curious about this too.

ILUVMILS 11-02-2020 12:00 PM
Smoke machine....

Shern 11-02-2020 12:31 PM
Figured I could use a motiv pressure bleeder pumped to a few psi.
Suppose it’s also possible to affix to the fuel neck -which now that I think about it makes a bit more sense- or via an old fuel cap.

Sugar Bear 11-02-2020 06:51 PM
Be careful to keep the pressure known, low and under control. A coworker put unregulated air pressure on a tank and didn't even have the filler neck sealed tightly; yet, it instantly ruptured the tank.

Good luck!!!

Diesel911 11-02-2020 08:00 PM
Quote:
Originally Posted by Shern (Post 4107133)
I suspect I have a pinhole leak somewhere in the fuel hard lines. Intend to unbolt them and check under the rubber but if it's a true pinhole, I don't suspect I'll see anything.

Remember reading someone suggesting pumping air into the tank.
I imagine clamping off the vent, the intake line and connecting the return line to a pump would be sufficient. What's a safe PSI to reach?

Or is this a bad idea in general?


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You might not locate the exact pin hole but since diesel fuel dos not evaporate in the manner gasoline does it is going to be wet and smell of fuel near the leak.
Degreasing the lines and then checking could work. It is likely under one of the camps (this happened to me). Either the Rubber wears out and the tubing rubs a hole in itself or it rusts under the clamps.

Shern 11-02-2020 08:11 PM
Quote:
Originally Posted by Diesel911 (Post 4107347)
You might not locate the exact pin hole but since diesel fuel dos not evaporate in the manner gasoline does it is going to be wet and smell of fuel near the leak.
Degreasing the lines and then checking could work. It is likely under one of the camps (this happened to me). Either the Rubber wears out and the tubing rubs a hole in itself or it rusts under the clamps.
Did you find wetness under the rubber or a visible hole?
As far as I can tell, I’m not leaking fuel. When I’m driving, it’s all suction.
After a full night and the suction has dissipated (and I lose a bit of prime), would be the only time it could conceivably leak any fluid.

gottarollwithit 11-02-2020 10:14 PM
How do you know that you're losing prime?

I'd probably just degrease everything, run it, then let it sit for a while. If not that, then use some dye in the tank and do the same

Shern 11-02-2020 11:25 PM
Quote:
Originally Posted by gottarollwithit (Post 4107386)
How do you know that you're losing prime?

I'd probably just degrease everything, run it, then let it sit for a while. If not that, then use some dye in the tank and do the same
Because I have air in the lines every morning. Visible, if I use the primer, audible by the nailing which lasts a minute or two until it's worked its way through.

This is a long running saga and literally the last thing to check...


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