Water in gas tank?

[Chris Dransfield]

My 70 454 has started to really bog down under hard acceleration (3500-4000). After changung the fuel filter there was no improvement and I am wondering if perhaps water has found its way in the tank. The plugs are fresh and the car runs perfect at idle and cruising speed.

I was told that running a quart of trans fluid through the a full gas tank would help eliminate some of the tank moisture. Suggestions and comments?

[Jimmy Johnson]

Re: Water in gas tank?

There is a paste called Kolor Kut (a water finding Paste)you place a thin coat on the end of a hose or rod and push it into the tank and it will change colors instantaneous in gasoline if there is water in the fuel. The tube I have ia a gold color and turns to red and soon as it touches water. I got mine from a local oil dealer. Kolor Kut is Manufactured by Kolor Kut Products Co. Houston, Texas. Jimmy

[Tom S.]

Re: Water in gas tank?

Criss
Do not run transmission fluid through your fuel tank. It will do nothing for the water.It will help clog your fuel filter and will be very hard on your carburator.Trans fluid is loaded with detergent and you don't want that at the gaskets and seals in your carb. Try putting in a couple bottles of dry gas or fuel treatment that says removes water on the label. And then every time you fill up put in a bottle. Especialy if you store it a lot make sure and keep treatment in the tank, very important.

Tom

[Terry D.]

Re: Water in gas tank?

Agree with Tom, do not run ATF through the gas tank. A little water would not give you the bogging down you describe, a lot of water I would think would effect it all the time, why not drain the tank? Can you take a flashlight and look into the tank. Alot of water would be easy to see.
Terry

[Richard Hayes]

Re: Water in gas tank?

Chris,

Water is heavier than gas. If there's any water in you tank-than that will be the first thing sent to the carb. First thing to do is replace the fuel filter.

Richard

[Mike McKown]

If you suspect water, do this first.

If this test doesn't find water then you can put this matter aside. As Terry said, a lot of water will cause problems at any speed (or even stalling).

If you find water in there, an easy way to get it out of the tank is to gravity drain it by jacking up the rear of the car and disconnect the input line at the fuel pump. You can gravity drain almost all of it in a pan. Then get a lint free rag on the end of mechanical fingers and swab it around in the tank through the fill opening until it is dry. Much easier than dropping the tank. If you start picking up a lot of crud and rust on the rag, drop the tank.

[Jim T.]

Re: Water in gas tank?

Chris I have had a little bit of water appear in my 70's gas tank. What I did to remove it was pretty simple for me. I removed the gas lid and hinge assembly. Them removed the rubber water catcher from the filler neck. The drain tube just slips off the outlet piece. Remove all the attachment bolts from the filler neck and remove the filler neck. I had nearly a empty tank, then remove the gas by siphoning or however you want. Before you remove the filler neck you should be able to see any water in the tank, there were small pockets of it laying on the bottom of my tank since water is heavier than gas. After siphoning all the liquid from the tank as possible, now just wipe it clean. Reinstall the filler neck with a new gasket, don't over torque the bolts. The gaskets for the filler neck don't last forever. I believe you will have to order one from Dr. Rebuild or another parts vender since GM does not have this part available any more. Joe Lucia made a post some time ago about making a gasket for the gas tank from a special gasket material that should be in the archives. If your in-tank fuel tank screen sock needs replacement, this will give you the access to replace it.

[Stephen W.]

Re: Water in gas tank?

Sounds more like the fuel pump is not up to doing its job at keeping the bowl full. Check your fuel pump to be sure its up to snuff. Its okay at idle and low speed cause it can supply enough fuel to maintain a full bowl but open it up and the bowl runs dry. Now a bad accelerator pump can give you a terrible bog as well. All that air and nothing to burn with it! Again at idle and normal operation doesn't require that big shot of raw fuel so it runs fine.

[Mike Cobine]

Re: Water in gas tank?

Have you changed fuel pumps lately? I found some rebuilt pumps did not flow the needed amount for a big block.

[Chuck R.]

Re: Water in gas tank?

Hi Chris,

If your tank is full of light rust and deposits, it may be that the stariner on the pickup line in the tank is plugging off.

It will be easy to see from the top with a flashlight.

Chuck