Gas pours out of tank when run hard

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Model T Ford Forum: Forum 2012: Gas pours out of tank when run hard
Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Thursday, August 09, 2012 - 05:08 pm:

1926 origal Fodor w tank under the seat. Filled tank 2/3 way then drove 10 miles at 85 degrees on steep PA mountain roads . When I stopped to let someone else drive it wouldn't start . Acted like a fuel problem so I looked at the tank and fuel was bubbling out the vent hole! I then drained three carb bulbs worth of fuel out of the holly nh carb after shutting the carb fuel line stopcock. Tank was overflowing... Scary . But then opened the stopcocks and drove away without problems. Did the fuel tank heat up too much .. ?? Fuel expanded that much ?! Am I to worry?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, August 09, 2012 - 08:00 pm:

The gas bubbling out the vent could be the combination of gas fumes and sloshing forcing the bubbling at the vent. Depending where your fuel line is routed, as long as the cool gas was flowing you kept the line full. But once the car was stopped the line heated up and so did the fuel inside it, getting vapor lock. Draining the gas at the carb allowed the line to purge any air.
You must have a magic car if you start with 2/3 of tank of gas drive 10 miles in hilly roads and end up with your tank over flowing with gas. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Thursday, August 09, 2012 - 08:13 pm:

That's what I don't get. The fuel line would have to be boiling hot to send hot vapor back into the tank and have it bubble out the vent. I mean REALLY hot! The exhaust pipe must have looked like a neon sign.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Thursday, August 09, 2012 - 08:46 pm:

I dont know either. My theory, although admittedly probably wrong, is that the tank got pressurized from the heat and expansion and forced gas through the carb float pin and flooded the engine ? When i opened the gas lid, the gas was level with the top opening of the tank on a level road. The tank was covered in gas . I like the sloshing and vapor lock idea, but that tank was topped-off full of fuel. Could it heat up and expand that much?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Thursday, August 09, 2012 - 08:52 pm:

My graandpa used to joke that his car got such good mileage that he used to have to stop sometimes and let some out!
I suppose the road tipping to the right some could shift fuel out the top. Anyway, I guess my real question is, how much do I have to worry about the exhaust or trans heating the gas tank, and does anyone use a heat shield?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan B on Thursday, August 09, 2012 - 10:05 pm:

Matthew - Heat shields should not be necessary, and would only mask the real problem.

I would start with the routing of your fuel line. Also that it is free and clear of any blockages (including sediment bulb).

One thing for sure, I'd definitely worry about your current situation. You're asking for a fire.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Thursday, August 09, 2012 - 10:31 pm:

Will do. Thanks for the advice.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, August 10, 2012 - 12:02 am:

Unless you have a right hand drive the gas tank would be well clear of the exhaust pipe.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Friday, August 10, 2012 - 01:10 am:

I'm confused. Was the tank 2/3 full or filled to the top?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kerry van Ekeren (Australia) on Friday, August 10, 2012 - 01:58 am:

Left or right hand drive, makes no diff, fuel line is in the same spot.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dane Hawley Near Melbourne Australia on Friday, August 10, 2012 - 06:41 am:

Check carefully- you probably have good coils that give you a 30% increase in mileage, Engine oil guaranteed to improve fuel consumption by 20%, a new fangled carby that gives 35% better miles to the gallon, then a 10% improvement from each of better wheel-bearing grease, modern coolant and new tires. That adds up to 115%, so naturally you have to stop every few miles to siphon off the excess fuel that the Fordor is creating.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Seth - Ohio on Friday, August 10, 2012 - 07:59 am:

The fuel line should be as straight as possible and not too close to the exhaust pipe or manifold. If it is too close it is "cooking" the fuel and turning it into vapor or a gas state. Because the fuel system is gravity flow the high end of the fuel line would be at the tank. As everyone knows the liquid fuel is heavier than the vapor so the liquid will flow down hill while the vapor will rise to the highest point which is the fuel tank. You need to move the fuel line from source of heat which would be your exhaust system.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Ashton Rosenkrans on Friday, August 10, 2012 - 09:34 am:

I've had the experience of filling the tank on my Model A on a hot day and having the gas expand in the tank and overflow. Filled to the usual shut-off point, put the cap back on, put the nozzle away, turned back to see gas seeping around the cap. Loosened the cap and gas gushed from the filler all over the cowl. Seemed to happen when the new gas was cold and put into a warmer tank. The gas expanded as it warmed up enough to overflow the tank. Now I don't fill up past 7 gal. and havn't had a repeat of the problem. Bit un-nerving when it happened though...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Peter Kable on Friday, August 10, 2012 - 10:16 pm:

Dane, Your calculations reminded me of a story friends told us about one of their members who announced at the start of the tour he had made some alterations to his T and was expecting to get far better mileage than he had been.

Each night they would sneak out into the motel car park and top up his fuel tank. All week the guy had this really big smile on his face as he was getting fantastic mileage.

At one stage he announced he was now up to nearly 50 MPG. He finally smelt a rat when he noticed the others trying to prevent themselves from bursting out laughing when he gave his latest improvement in MPG.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Monday, August 13, 2012 - 09:00 am:

It was filled by my son, but looked about 2" from the top. My fuel line is pretty straight and not touching anything along its path. The fuel was cold and the day was pretty hot . It was pretty scary . I won't fill it that high again unless it's warm, that's for sure. My passenger, who was riding for the first time, sure was scared...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Monday, August 13, 2012 - 02:45 pm:

Hey Peter, I need friends that want to pull pranks like that!! Lol, I'd brag about my mileage all the time if it kept the tank full.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Floyd Voie - Chehalis, Washington on Monday, August 13, 2012 - 08:53 pm:

Remember the neighbor in Herbie the Love Bug?
Very similar to your story Peter except after putting extra gas in the neighbor's car on a regular basis they then began to siphon it back out....drove the neighbor nuts!

Matthew, I think Wayne has described what most likely happened with the gas overflowing.

Good Luck!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Tuesday, August 14, 2012 - 11:00 am:

Peter, if yours friends would like to top off my car's tank every night, they can laugh at me all they want. Thanks to everyone for their help.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Tuesday, August 14, 2012 - 11:19 am:

Hey, check out the incredible picture of the burned out Overland car on the "fuel line question" thread. Looks like I narrowly avoided the same fate.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Dimock, Newfields NH, USA on Tuesday, August 14, 2012 - 12:55 pm:

If it is a round tank and filled 2 inches from the top there is very little space for expansion.

Gasoline expands and contracts based on temperature, the industry uses a standard temperature of 60 degrees Fahrenheit as part of its definition of a gallon. Thus, a gallon of gasoline is the amount of fuel that occupies 231 cubic inches at 60 degrees.

At 75 F degrees, the same amount of fuel occupies 233.4 cubic inches.
At 90 F degrees, the gas expands to 235.8 cubic inches.

If there are 7 gallons of gas in the tank at 60 F and it heats to 75 F it takes up an additional
16.8 cubic inches.
If the day is really hot and the gas gets to 90 F it takes up an additional 32.6 cubic inches


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew Eppley on Tuesday, August 14, 2012 - 04:26 pm:

Brilliant calculation. Finally some facts! Thanks, I will definitely not overfill, or maybe get a fuel line overflow kit.


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