The Stovebolt Site Forums The Shop Area Engine Shop Gas leaks everywhere!

At this point I have replaced or rebuilt Ernestine's fuel system up to the manifold. I'm having a hell of a time keeping several of the flare connections from leaking. I thought I finally had them all tightened up nicely Saturday evening. I put the battery charger on and tarped everything up for the expected rain. I went out to try to start her this afternoon and found that the fuel pump connection was dripping again and the connection at the top of the tank had leaked a good bit into the cab (glad the charger didn't blow the whole thing up) . When I removed the gas cap, it had a good bit of pressure built up in the tank. Should my brand new gas cap be vented to prevent this pressure buildup? Also, is there anything that might keep my flare connections from leaking?

Hi, vented cap is necessary for these trucks.BE CAREFUL NOT TO OVER-TIGHTEN THE FITTING AGAINST THE FLARE. This ruins the 'seat' on the flare and no amount of tightening will stop it. Good luck,Tom.

Tom's right about the cap and tightening flares.

However, which style flare are you using? If they are the double flare, you shouldn't be having problems with leaks. They do a good job of sealing. If you're using the standard plumbing flare, I would strongly suggest switching to compression fittings.

OMG, a gas leak causing gas fumes under the tarp together with a battery charger.

That could have been a very loud boom...

Could the fact that I am using stainless steel lines be the reason that the connections are not seating well? Harder metal? I'm grasping at straws here.

Using a vented cap may solve all your problems at once. As the vapor builds pressure in the tank, it looks for any escape route available. Unless your lines and fittings are rated to over 100 PSI, the leaks shouldn't be any surprise. Get the right cap first.

Ralphy, the pressure Hedgehog is talking about comes from expanding fuel vapor in the tank. As the temp rises, more fuel vaporizes, then the vapor starts expanding. Don't know how high it would go, but it could cause leaks.

I would guess the problem is caused by the stainless line fittings. I would call the supplier and ask for advice on them.

53 Dumpy,

Did you flare the tubes or did you buy them ready-made?

What grade of stainless steel (304, for example)?

Inline Tubes states that their stainless tubes seat as easily as standard steel tubes.

I recently had problems with leaking stainless steel brake lines and almost gave up until I reread the instructions from Inline Tubes. They suggested checking the seats on the flare end of the tubes and the seat in the receiver-fitting; and, they suggested tightening/untightening/retightening the fittings to make a new seat/seal. After following this procedure (and not being too gentle with the tightening torque), I got rid of all my leaks.

All my gas lines (on both trucks) are also stainless and the leaks I have are from loose brass fittings into the carburetor (I am going to break the rules and use teflon tape - a risky thing to do).

Good luck,
Tim

Ralph, I'll have to remember that trick the next time I use my Oklahoma credit card.

As for the pressure, I think 100 psi would make that fuel tank balloon pretty bad and blow off any rubber hoses anywhere!

Ralphy,

The SS gas line goes into the gas filter (no leaks) at the carburetor. The brass fitting between the gas filter and the carburetor is leaking at the carburetor.

Thanks, Tim

wow 100psi, no wonder they are recalling these all trucks...

Ralphy,

Thanks for all the advice.

I have tried new fittings. It seems that the "receiver" on the carburetor is wallowed-out or expanded from overtighening and/or former use of wrong-threaded fittings/adapters (on three of the four carbs I have tested).

I like the JB Weld idea - it might be permanent but who cares. The brass fitting/adapter might as well be permanent and the JBWeld is less likely (compared to teflon tape or liquid-seal) to sluff off and clog the internals of the carburetor.

Thanks, Tim

tclederman you may want to check into Permatex's Thread repair kit. It is basically an epoxy kit but comes with a release agent that allows the Male threaded part to be removed and reused.

Good luck

You guys are a wealth of information. I got my lines from Inline Tube and unfortunately didn't read their installation instructions very closely since they were for brake lines. As for the tightening and losening to form a new seat, I have probably done that trying to get the darn things to quit leaking. I will pull them off and take a look at them though. I'm not sure my cab will ever loose the gas smell. Three days with the windows open hasn't affected the odor at all.

Tim's siphoning story sparked a memory of mine. I had gone to my grandmother's place for vacation one year. The afternoon we arrived my uncle came in wanting some help getting a truck back home that had quit on him earlier in the day. He had to get to town to pick up trailer before a business closed so he just dropped me, tools, and a water jug off at the dead one (a fjord by the way, you know "Found On Road Dead" or "Fix Or Repair Daily). I determined that it was not getting any fuel to the carb. When I unhooked the line from the tank there was no gas. OK, need to see if the line from the tank is clear. It had a cab mounted tank so I decided to blow as hard I could into the tank to pressurize it and see if I could force some gas through. Sound like a good idea, right. The biggest problem was that uncle had topped the tank off before heading into town. I pressurized the tank all right, but the fuel level was above the filler pipe. My contribution to the tank pressure caused a large amount of gas to spray all in my face and soak my entire front when I removed my mouth from the filler tobe. Bad situation in any light, but standing by the side of a lonely Arkansas highway totally soaked in gasoline is not much fun. Luckily I had the gallon water jug and was able to at least rinse my face and eyes. About forty five minutes later my uncle drove up and was quite surprised to find this gas soaked, bare chested, and quite unhappy teenager. I learned a few things that day 1)don't ever blow into a gas tank 2) gasoline applied to skin in 95 degree heat and humidity is less than comfortable 3) I began to dislike fjoords greatly that day.