Pressure test 2 line fuel tank

[tonynoriega2]

Some of you may have seen my previous post about a fuel tank diaphragm...

Well I used what I had, poked a hole in it, and put some new washers on.

I am fairly certain, everything has been put back together properly and seated and sealed...

This may be a dumb question... but how can I pressure test an empty tank?

Or is that even possible?

Am I only going to really find out how well it works by filling it with gas and priming it?

Sorry.. noob questions here.

 

[Bosunsmate]

Re: Pressure test 2 line fuel tank

You can leave it out in the sun and see if the pressure builds up and hisses when the lid is taken off,,.
Or if its leaked out prior

 

[tonynoriega2]

Re: Pressure test 2 line fuel tank

Ah... power of the sun.

Would it be advisable at that point to spray the outer seams, and gasket areas with soapy water to see if there is any air coming out ?

You can leave it out in the sun and see if the pressure builds up and hisses when the lid is taken off,,.
Or if its leaked out prior

 

[Chinewalker]

Re: Pressure test 2 line fuel tank

Won't hurt if you think it's still leaking.

 

[oldboat1]

Re: Pressure test 2 line fuel tank

you a smoker? Before you quit for good, take a deep drag and put the butt down in a safe place. Blow the smoke in the tank, and replace the cap. Press the primer button a few times, and see if there is any smoke leaking from the gasket(s) anywhere. Additionally, you should get a slight hiss when you go back and unscrew the cap (Let it set for a minute or two to see if it holds pressure.)

I guess I usually just test tanks while running the engines. As long as the primer pump is working and I can get gas to the motor, the motor pressurizes the tank and it's easy to listen for leaks (soap and water spray also good at that point).

 

[Bosunsmate]

Re: Pressure test 2 line fuel tank

Ah... power of the sun.

Would it be advisable at that point to spray the outer seams, and gasket areas with soapy water to see if there is any air coming out ?

Yes you could works well, on my BBQ

 

[HighTrim]

Re: Pressure test 2 line fuel tank

you a smoker? Before you quit for good, take a deep drag and put the butt down in a safe place. Blow the smoke in the tank, and replace the cap. Press the primer button a few times, and see if there is any smoke leaking from the gasket(s) anywhere. Additionally, you should get a slight hiss when you go back and unscrew the cap (Let it set for a minute or two to see if it holds pressure.)

I guess I usually just test tanks while running the engines. As long as the primer pump is working and I can get gas to the motor, the motor pressurizes the tank and it's easy to listen for leaks (soap and water spray also good at that point).

I don't understand how this would work, or why it would hiss? Wont get any pressure in there until after it is connected to the motor and running for a while right. The button simply works like a fuel bulb to fill the carb bowl, doesn't pressurize the tank, the motor does that.

 

[oldboat1]

Re: Pressure test 2 line fuel tank

might be right. I know I have released pressure (and gas) at the motor end with a phillips screwdriver -- maybe doing that and then pumping would create some pressure. Like i said, I'm usually checking tanks when hooked up, and I'm sure that's the best way (maybe the only way, if you are right.) Let's see, you could probably check to see if the tank was airtight by removing the motor connection and hooking up a MityVac to the air line -- pretty good chance it would hold pressure if it held a vacuum.

 

[racerone]

Re: Pressure test 2 line fuel tank

This often misunderstood.---The primer button does NOT put pressure on the fuel..----The primer button pumps fuel into the carburetor.--When motor is spinning ( even with recoil starter ) it starts to put crankcase compression into the tank !

 

[oldboat1]

Re: Pressure test 2 line fuel tank

well, if the snow clears I'll check to see if pumping an empty or almost empty tank incidentally creates any pressure at all -- but take your point. So suppose one takes off the engine end of the hose, plugs the gas line, and uses a bicycle pump needle, or similar, to pump some air into the tank -- could test both the amt. of pressure, and duration the tank holds without leaking.

(ah, or blew that puff of cigarette smoke into the tank that way....)

 

[racerone]

Re: Pressure test 2 line fuel tank

The primer button would pump air out of the tank.----Not sure why this simple concept is not understood !!!-----When you take the connecter off the motor both hoses seal off automatically.--That is if the o-rings are in good condition !

 

[oldboat1]

Re: Pressure test 2 line fuel tank

and that's what the thumb is for. Remove the hoses at the connector, block the gas line, blow into the air line.

 

[racerone]

Re: Pressure test 2 line fuel tank

Apparently this tank is all refurbished so it should have new o-rings in the connecter end.---A spare cap with a shreader valve is the ideal way to test.

 

[oldboat1]

Re: Pressure test 2 line fuel tank

yeah, could be. just messin' Racer. expected Reeves or Robb or somebody to jump in and say something about just "blowing smoke." kind of disappointed. Best.

 

[HighTrim]

Re: Pressure test 2 line fuel tank

Ok here is how to test the running ability of a tank, but you still need the motor. If you want a gauge they are easy to make, I can sell you one 10 percent off.




Now, I suppose you could "pressurize" a tank by blowing air into the air line after removing the connector. Not sure how you would test quantitatively how well it holds. More of a qualitative test. This gauge gives you a definitive answer.

Have to admit though, I rarely use it. Rebuilt a gazillion tanks now, they just seem to always work

 

[oldboat1]

Re: Pressure test 2 line fuel tank

They either seem to work or not, and almost always the former after regaskets or new o-rings, like I hear you saying.

With that gauge, it seems to me there is a problem if the connector is still in the system. You would have to be sure the leakage, if there is any, is at the tank and not the connector. And that's why I think (if I REALLY wanted to test a tank), I would bypass the connector. I have a foot pump with a gauge, and it seems to me that would be a good way of testing the tank connecting directly to the air line.

But if pushed, I think the smoke test could work too if enough air introduced to force smoke visibly through any leaks. Granted, I haven't tried it.