View Full Version : TR2/3/3A Fuel Evaporation

07-01-2018, 05:56 PM
I’ve been neglecting my driving duties on the TR2 while dealing with a house renovation. I’ve been starting the car....mostly to move back and forth in the shed...every few weeks, but have not had it out where I really paid attention to gage readings, like, gas?!? Well today I opened the shed, pulled it out for a nice drive, left it running while I close the shed door, and...put, put...put........put..........put. Die.

A quick check of the fuel gage and it was bone dry. Here’s the interesting part, it had exactly 5 gallons in it when I parked it 4 months ago. So, my rough calculations are:

Burned maybe 1 gallon moving the car around.

Well, I guess that’s it. Nothing else to calculate! And “no”, it is not leaking it. There is no fuel smell in the car and no spots on the ground, plus I busted my tail last year cleaning up all the leaks.

Here’s all I can figure happened. I started the car about 5 times over 4 months. I figure the fuel in the bowls must be about a pint for each start?? So about 3/4 of a gallon evaporated from the bowl vents. But the other 3-1/4 gallons had to evaporate out of the tank vent! Granted, it has been over 100 degrees here, but WOW. The amount of time it ran before dying was about what I would expect from fuel in the line...but the tank was bone, dusty dry. I never would have figured.

Anyway, the fix is to get it out and drive it more often!

Alfred E. Neuman
07-01-2018, 05:59 PM
Look at it this way - the C02 from burning it is waayyyy better for the environment than letting it evaporate. We all need to do our part and burn as much of it in our TRs as possible.:eagerness:

07-01-2018, 09:08 PM
I have noticed fuel evaporation in the past on my ‘3 as well, if I haven’t driven it for a couple months.
Wound up stuffing thin plastic sheeting between the cap and filler tube, which has seemed to have helped.

07-02-2018, 08:00 AM
I have noticed fuel evaporation in the past on my ‘3 as well, if I haven’t driven it for a couple months.
Wound up stuffing thin plastic sheeting between the cap and filler tube, which has seemed to have helped.

I do the same thing. Also, if the car sat for a few months, even with Stabil in there, the fuel would begin to lose it's volatility. The plastic, I use one of those sandwich bags, has stopped that also. Just remove it before a drive. :smile-new:

Marvin Gruber
07-02-2018, 10:10 AM
Ran out of gas in the 250 last week, had not driven it in months. I knew I had put 4/5 gallons in it last time I drove it. The 56 TR3 did same thing last year. Thought the same as you John.

07-02-2018, 11:09 AM
It kinda' makes you wonder if the gasahol is more prone to evaporation?

I did have fun that last couple days with the TR2. I forget how nice these cars drive compared to the new junk. My wife has a bad back, so I am always looking for cars with smooth suspensions. Saturday we test drove 2 brand new Cadi's. I swear the TR rides smoother than either of them! Not much travel on the TR, but for most normal bumps it glides right over them. The Cadi's new fangled magnetic suspension is, well, rough in my book.

One thing, right before I parked the TR2 again the clutch started making weird crunching noises when letting out in first gear. No other time...just first...and it otherwise felt fine. I'll have to schedule some time to look at that.

But not until the temperature goes below 100's!?!

07-02-2018, 11:57 AM
Do any of the Big 3 sell the rubber seal that goes into the gas cap? Seems to me they either deteriorate or disappear over time. I looked at my cap seal and there was barely any rubber there at all to make a good seal.

07-02-2018, 05:08 PM
I think I have a TR4 cap on my TR3, and I drilled a vent hole under the lid and plugged the normal tank vent. It's probably as hot in my garage as Johns, and my car sits too often, but I've never noticed a drop in the fuel level from when I parked it.

-But I don't have teenagers with access to keys... and my wife doesn't drive the TR3. (just sayin -who would blame them?)

Geo Hahn
07-02-2018, 05:46 PM
Do any of the Big 3 sell the rubber seal that goes into the gas cap?...

Are you referring to the seal that sits in the groove in the base of the fixture?

If yes, I made on from an extra o-ring that came with a cartridge oil filter (they usually give oyu two and I saved some extras). I cut it to the correct length and jammed it into that groove. It's only sealing vapors so I just relied on the ends pressing together for a good enough seal.

I, too, have never experienced fuel evaporating from the tank to any appreciable degree.

07-02-2018, 06:38 PM
A cold weather blend would evaporate faster in warm temps because of the higher butane content added for easier cold starts.
At least that's what I remember from a stint in a refinery a longtime ago.

07-02-2018, 06:42 PM
So I found info on an old thread on this topic. The seal is available from Revington TR part # RTR 4073 for 2.69 pounds....but shipping???

07-03-2018, 09:13 AM
John did you not say you purchase one of those aftermarket tanks? I had one in my 1961 and the gas would slush around in it like the tank was simply a barrel. The stock tanks have this compartment or something where the vent pipe comes out, so perhaps the speedy evaporation has its origin there. I have not been driving mine either and I did notice that the gas mileage was worse, but nothing like what you said.

07-03-2018, 10:01 AM
Yep, it’s a new tank...and not very good looking at that. I remember that it has some baffling in it, but judging from the outside, it’s likely not as good as the OEM.