Can't find the leak in my tank

[zopperman]

Hey guys,

I have a 22 gal. alum. tank and I've sealed every divet and pressure tested it about 10 times. I kept finding leaks, generally around the sending unit, but I've sealed it all off. I sprayed it with soapy water while it was at 5 psi, and no leaks anywhere. Let it sit overnight and now it's at 3 psi. the water isn't bubbling anywhere. I;ve checked all my seals, and nothing. any ideas?

Zak

 

[RogersJetboat454]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Hey guys,

I have a 22 gal. alum. tank and I've sealed every divet and pressure tested it about 10 times. I kept finding leaks, generally around the sending unit, but I've sealed it all off. I sprayed it with soapy water while it was at 5 psi, and no leaks anywhere. Let it sit overnight and now it's at 3 psi. the water isn't bubbling anywhere. I;ve checked all my seals, and nothing. any ideas?

Zak

Perhaps there is a microscopic leak some place? Honestly it sounds like you got the tank sealed enough to be fine. Keep in mind the tank is vented, so it shouldn't even be building up much pressure in the tank.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

I'm slightly confused to as how tanks work. I know I ened the vent, but I imagine that, in order for the motor to effectively pull gas out, it would have to create a vacuum? I also don't want to be leaking fuel/fumes into the bilge and air

 

[rockyrude]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Yes, the motor fuel pump creates a vacuum on the fuel line. In order for the fuel to leave the tank, it must be vented to allow an equal amount of air to replace the fuel taken out. There should not be any fuel in the vent hose, and there are minimal fumes, although your bilge SHOULD have a blower on it to pull any fumes out.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

So will this pinhole have any effect? Should I fill the tank with water and look for a leak? I'm worried that will damage the sending unit, as it says not to be used with water..

 

[RogersJetboat454]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

So will this pinhole have any effect? Should I fill the tank with water and look for a leak? I'm worried that will damage the sending unit, as it says not to be used with water..

Loosing 2lbs over the course of a night is less than a pin-hole leak. As I said, this tank is not under pressure or vacuum. With an always open vent, the only pressure/vacuum on the tank is going to be changes in atmospheric pressure.

I still think you may be confused about how this tank works. There is a fitting on the top of the tank with a tube that goes down to the bottom of the tank, correct? The fuel gets drawn up that tube by the fuel pump like someone sucking on a straw. As Rocky said, the vent is in place to replace the volume of fuel drawn out of the tank with an equal volume of air.

 

[GA_Boater]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Zoop - A while back you posted after using JB weld to fix your tank holes and I suggested pressure testing before you buried it under your deck. You smeared a lot on that tank. I hate to say it, but I don't think it worked. You have two, actually three choices, now ignore it, buy a new or used tank or try using a tank sealer. You have to make the decision.

 

[Thalasso]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

jb weld doesn't work on gas

 

[RogersJetboat454]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Zoop - A while back you posted after using JB weld to fix your tank holes and I suggested pressure testing before you buried it under your deck. You smeared a lot on that tank. I hate to say it, but I don't think it worked. You have two, actually three choices, now ignore it, buy a new or used tank or try using a tank sealer. You have to make the decision.

Didn't know this was a JB weld repair....
I wouldn't have been using JB weld to repair the a gas tank in the first place.

Zopper, I would be looking for a new tank, or find some place that can clean the tank, and weld it up if it's even worth it.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Well, I did use JB weld all over the tank, but it wasn't a repair as much as it was a preventative measure. The tank had a bunch of divets so I filled them with JB weld so they wouldn't pop under load. Wouldn't a leak from the tank itself start bubbling with soapy water? I also used PC11, which says it's a tank sealer around the actually leaks. One was around the stern side fitting that feeds the engine and the other was around the sending unit where it was leaking..

Thalasso, what do you mean JB weld doesn't work on gas? As in gas eats through it?

What would ignoring it do? I definitely can't afford a new tank. I'm relatively certain that it's not at the fault of the JB welded divets...

 

[GA_Boater]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Ignore as in forget about it. It was just one of the choices. It isn't a fix for you problem. PC11 http://www.pcepoxy.com/our-products/paste-epoxies/pc-11.php is not a fuel tank leak repair. I get the impression that your tank has many spots of corrosion and you are trying to stick bubble gum on it. Buy a 6 gal plastic tank at Wally World and use until you can afford to replace your current tank.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

I meant, what would be the consequences of ignoring it? It wasn't corroded as much as it had these little nicks in it, almost like a chip. they were REALLY tiny, like maybe 1/32" inch... they didn't go through the tank all the way, so nothing was necessarily leaking.. that's why I'm confused. and if there is a leak, why isn't it bubbling with soapy water under pressure?

 

[GA_Boater]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

First if you were doing a repair for looks, why? The tank is under deck, won't be seen. So I have to assume you have leak concerns.


I have no idea how you are pressure testing, so I can't comment on the lack of bubbling except if you lose pressure over night it's one of two things. You have a leak in the tank or your test rig leaks. Maybe your lucky and one of the hoses are leaking and not the tank.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

I have a bike pump hooked up to a pressure gauage. I've sprayed the hoses anbd made sure the clamps were tight and NOTHING bubbled on them...

I'm redoing my deck so the tank had to come anyway and it needed a new sending unit. I wanted to make sure that these little nicks didn't make it all the way through the tank and become a problem... that wa sth reason for repair.. less repair than prevention...

 

[GA_Boater]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Ok, more pressure - 10 or 15 PSI. Spray bubble juice. No bubbles, then call it good.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Just did it with 10 PSI... no visible bubbles anywhere I'm going to let it sit and see if it drops. Worst case, if I can't find a leak, what will happen as a result of leaving it?

 

[GA_Boater]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Are you leaving the pump hooked up?

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Nope, I disconnected it for every test... I sprayed the gauage and hoses too...

 

[GA_Boater]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

use it.

 

[zopperman]

Re: Can't find the lak in my tank

Re: Can't find the lak in my tank

Yeah.. that's what I figured. I'm going to hook it up with half a tank to the motor and run the motor and see if it works. I already spent 70 bucks on a new sending unit/fuel gauge...