Water in gas, repeating issue
Thread Starter
3rd Gear
Joined: Aug 2011
Posts: 3
Likes: 0
Water in gas, repeating issue
I am having an issue with water in my gas tank. Each time that water somehow ends up in the tank, I pump out the fuel until there is no more water coming out. However, it always seems to start missing and lagging a few months after, and it turns out to be water in the gas. For reference, the carb is a Holley 4160 600cfm. When I feel inside the tank, there is what seems to be condensation inside the tank. The tank has not been filled to the top in a few months, it usually stays around 1/4. Has anyone else had this problem? The car is stored outside. I doubt that is the gas, as my lawn / garden equipment, as well as a 75 vette, get gas from the same station. Any and all help is appreciated. The carb is around 3 months old, and really don't want to have to clean water out of it.
Thank you
Thank you
Drifting
Joined: Jul 2004
Posts: 1,695
Likes: 65
From: Kissimmee fl
Finalist 2021 C3 of the Year - Modified
2017 C3 of Year Finalist
Cruise-In VIII Veteran
St. Jude Donor '07
Don't know where you are but a partially filled gas tank is just ripe for condensation. Keep your tank full of gas, keeps the amount of moisture getting into the tank to a minimum.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Only two ways for significant water to get there, either was in the gas when you put it in there or came in through the filler neck after. Usually the drain hole in the boot under the filler neck is stopped up and water backs up over the neck. It is a common problem. Open that hole, cut out a chunk so the damn thing don't stop up, or best, remove the boot completely. It will stop the problem.
Burning Brakes
Joined: Aug 2005
Posts: 801
Likes: 1
If your using ethanol put some fuel stabilizer in it made for marine use.Keeping the tank full will certainly help.I do both and have never had an issue with water.Temp fluctuation and having a 1/4.tank of gas is ripe for condensation.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I agree that a plugged drain hole in the boot around the filler neck (just under the gas cap) will cause you to get water in the tank every time it rains and/or whenever you wash the car. Use a long piece of wire to run through it and remove any blockage. If this is your problem, you also need to check the status of the fuel cap gasket [assuming you have a non-vented gas cap].
You can also put some alcohol in the fuel tank. Alcohol will allow water to dissolve (or mix) with gasoline. If there is not too much water in the tank, the fuel will burn fine with the extra water in it.
The other possibility is that you have a neighbor who doesn't like you or your car!
You can also put some alcohol in the fuel tank. Alcohol will allow water to dissolve (or mix) with gasoline. If there is not too much water in the tank, the fuel will burn fine with the extra water in it.
The other possibility is that you have a neighbor who doesn't like you or your car!
Last edited by 7T1vette; Sep 12, 2011 at 01:09 PM.
Instructor
Joined: Nov 2006
Posts: 130
Likes: 1
From: Wylie TX
I agree completely with 7T1vette. however, I would not remove the boot from the filler cap, as a previous owner did that to the Corvette I now own and the top of the gas tank rusted out. Which made for an even bigger mess for me to fix. Just my two cents worth.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
I will bet you that it will rust from the inside much faster than the outside. The top is slanted and will dry off quickly, unless you keep it outside in a region that is ultra wet, I dont think outside tank rust is much of a problem. It could increase the chance of rust under the padding and straps. I will chance that in order to keep the other things like lines, and carb from failing from all of the internal rust. I agree that keeping the drain clean is a better solution than removing the boot, but most don't think to check it and they get water when the drain stops up, and it don't take much to stop it up. Another stupid design that causes expensive problems.
Race Director
Joined: May 2006
Posts: 18,742
Likes: 2,583
Cannt seem to find what year car you have. I know certain years, such as 1969, used a cork gasket between the neck and the tank. If the gasket breaks up and water gets on the top of the tank it will run into the tank.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Only two ways for significant water to get there, either was in the gas when you put it in there or came in through the filler neck after. Usually the drain hole in the boot under the filler neck is stopped up and water backs up over the neck. It is a common problem. Open that hole, cut out a chunk so the damn thing don't stop up, or best, remove the boot completely. It will stop the problem.
the logical choice except you need not remove the rubber boot surrounding the gas cap just clean the drain hole out.......and they all have one
Intermediate
Joined: Aug 2010
Posts: 31
Likes: 0
From: blairstown nj
A c3 doesn't have to be very old for this to happen. happened to my 71 lt1 when only 2 years old. boot filled up in the rain and the gasket had a ripple in it. got a lot of water in the tank. check the fuel cap, gasket, and the boot drain.
