The Stovebolt Site Forums The Shop Area General Truck Talk Plugged Gas Tank

I have a plugged gas tank outlet in my 37 Chevy pickup. The plug held against 125 psi for twenty minutes before it gave way. It came back in 10 seconds after the pressure was removed. Repeated process 4 times - same result each time except clearance time was essentially zero.

I realize I must pull the tank and clean it. It has about 10 gallons of premium (non-ethanol) in it right now. I will siphon the gas out as best I can, then remove the needle valve and 1 1/2" nipple from the outlet. I will disconnect the fuel level rheostat and remove the straps. The tank should come out at that point.

My question is, what the heck is plugging this tank? Tar? I used brass compression fittings to attach the fuel line from the fuel pump to my compressor and loosened the gas cap. I was amazed when it didn't clear immediately. This stuff is tough! How do I clear it out if I don' know what it is? I was going to use oxalic acid to clean the tank, but if that stuff is tar, that may not be a good idea. I am hoping to get a small sample when I remove the needle valve.

You guys have saved my six before, I am hoping someone smarter than me can figure this one out.

I am not sure where this post should go. Will I ever get to ride in this truck? Stay turned for the next thrilling episode of Jim vs the Old Iron!

Jim

Why not bring the take to a radiator shop to get cleaned out?

They are set up to do a better job then someone at home.

They always want to cut the tank, and this truck is an all original as best as I can keep it. Cutting the tank just isn't an option at this point.

Jim

Who knows? Rust, varnish/tar, old screen or float parts... Just gotta drop it, scope it, stick a "stick" in the outlet to release the object(s). Maybe run a wire thru the fill hole or sender hole to outlet? Clean, flush, test, install. The usual grunt work we all do and hate. You can use water to test. Hope it's not still under the seat. This tank is supposed to have two outlets?

The tank is under the seat, and is reputed to have two outlets and two inlets plus the entrance for the fuel level rheostat. The choke point for the plug is the outlet needle valve. Not much is going to pass through that needle valve but non-viscous liquids. To this point, none of the bolts, screws, or nuts have been rusted. I am hoping the nuts for the straps are in good condition, and the nipple that screws into the tank comes out with no problems. I am just amazed Chevy used a needle valve as an outlet.

Jim

Don't know anything about that system. Thought you would use the other outlet if one blocked. Can you delete needle valve. Don't understand that? Gravity feed with a fuel pump? What does valve do for the cause? Anyway, I'm sure you will clear it.

So Jim... what was the outcome??!!
Greg

....this didn't sound like the original gas tank in my 37. Mine has only one outlet. There is a system in the tank to vent fumes out the bottom of the tank though. Perhaps someone else had it lined/coated and it is coming off. It'd be tough.

Perhaps this link will help?

http://i140.photobucket.com/albums/r19/LutherParris/Ole%20Blue%201937/IMG_0001-1.jpg

Sounds like you are the newest member of the ethanol-makes-an-excellent-deposit-solvent club. While the old formula gas left the deposits clinging to the sides of the tank, the new formula seems to cause them to slough off and clog up the works.
It may not be the ethanol doing it, but more likely the highly volatile components added to make the ethanol work as a fuel.
Carl