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Triumph TR6 - Gas Fumes

Hi Guys,

I have a dangerous situation, I opened my garage door a week ago and was choked by the amount of gas fumes in the garage. Since then I have pulled and inspected the gas tank for leaks, checked the gas cap seal, added clamps to all gas line and emmission tubes that did not have them. I found no ligiud gas leaks and still have a high amount of fumes.
Any ideas on the possible origin of the fumes?

Thanks in advance,
Ken
L Caya

Did you check the bottoms of the pump and carbs?
DON KELLY

Hi Don,
Yes I did, no leak. I even added clamps to the hoses from the emmission canister to the carbs.

I pinched off the emmission hose at the tank to isolate the tank, after driving for a while I stopped for gas. when I openned the gas cap I heard air rush in, indicating the tank had a mild vacumm. So, no fumes or leaks from the tank or gas cap.

Still at a lose!
Ken
L Caya

Ken, what year is your 6? There could be another "holding tank" for gas in the boot.

Rick
Rick Crawford

Das Boot!
DON KELLY

Rick,
It's a 72.
There is a small tank sitting on top of the main fuel tank, the vapor line runs to it then on to the charcoal canister. Is that the tank you'r refering to?

Ken
L Caya

That's it. Here is the routing for that year and later lines. You might have an open line somewhere.
http://www.zeni.net/trf/TR6bluebook/26.php

But I take it this is new?
DON KELLY

Any chance that gas is finding its way into the crank case from a leaky fuel pump or stuck float needle valve?
Berry
BTP Price

I'm thinking the same thing . That new gas does a number to the fuel pump inerds I'd rebuild it and use these parts
http://www.maritimedragracing.com/then_and_now_automotive_part.htm
DON KELLY

If the gas gets into the oil pan how do the fume escape? The valve cover is vented to the carbs.

Berry, would a stuck float needle valve cause the idle to drop to very low rpms (close to stalling if not stall) when you take your foot off the gas while pushing in the clutch and then slowly comes back to 850 rpms?

Another clue I just realized that when the tank is 1/4 full or lower the fumes aren't as bad?

Ken
L Caya

Is it possible that the charcoal cannister is saturated?

Ken
L Caya

It's possible the cannister is saturated, but the sort of strong fumes you're talking about are almost always due to a liquid leak. You may not see it on the floor as the liquid is always evaporating & smelling up the joint. The fact as you say that the odor is not as strong with the tank level at 1/4 makes me think fuel line, pump, & especially carbs. I'd go over all the fuel line from the tank to the carbs again, and consider changing the o-rings in the bottom of the float bowls.
Brent B

Brent,
Your right, one drop of liquid creates a lot of fumes.
Wipping my hand under the carbs and the fuel pump produces no liquid, but that is after it has been sitting over night, I will test again after a drive.

I will also clean the entire fuel line and vapor hose, then check again for leaks.

Thanks for the suggestion, at this point I'll try anything.

Ken
L Caya

Ken-If the needle valves were stuck open, the plugs&exhaust would be very black and or gas would drip from the carb.
Sniffing the dip stick is a good test for gas in the oil. I never thought about how the fumes would escape from the crankcase,but because the fuel level is higher than the pump when the tank is about 1/2 full or more, it is not that uncommon. A shut off valve is cheap insurance against it happening, especially during long storage with a full tank.
Berry
BTP Price

Ken
No that is not the tank I was refering to. Prior to 72, there was an extra small tank (emission tank) located on the pasenger rear inner fender. It was a direct link to the fuel tank and over the years could get slightly filled with gas or even rot out.

Rick
Rick Crawford

Rick, don't believe the 72 has that
DON KELLY

Like I said Don "Prior to 72"

I agree, 72 did not have it.

When gasoline drips it will eventually evaporate, BUT it will leave a stain!




There is nothing better than putting a piece of cardboard or something under our cars to see "where is it coming from"??????

Rick
Rick Crawford


Update,
I pulled the tank, sealed all openings, connected an air line to the gas outlet tube and put 20 psi into the tank. I then sprayed soapy water on the tank seems, saw bubbles at the fuel gauge flange and mounting screws. I removed the gauge sending unit, sealed it and replaced.

now no bubbles.

I then filled the tank with 11 gallons of gas and let it set over night with fume vent and gas outlet sealed.

NO FUMES.

Next step connect only the vapor line to the tank with it disconnected from the canister and plugged.

Ken
L Caya

Sounds like your gaining on it
DON KELLY

I hate to sound like the old maid, but one should be very careful putting pressure on old gas tanks like that. It could easily have gone "spherical" or even come apart, which could be dangerous.
Brent B

I tested the tank with the fill cap inplace, its design includes a pressure release spring on the rubber seal. I mis-led in the previous posting, the air regulator was set at 20 psi, however, the fill cap would release excess pressure and hold something less preventing any damage. I also used a hand control trigger at the end of the air hose so I could control the rate of air flow.

Thanks for the concern and word of warning.
Ken
L Caya

Ken

Now that you mention it, when I replaced the seal on my fuel sending unit at the tank last year, the gas fumes I experienced went away. But they were only noticeable when I filled the tank up to full.
Michael Petryschuk

This thread was discussed between 03/05/2011 and 14/05/2011

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