79’ fuel tank help

rghouse

SILVER Star
Joined
Mar 1, 2015
Messages
745
Location
Oroville, CA
Getting ready to put the fuel tank on the 79, but figured I need to do inspect it before hand. Dad had the inside of the tank cleaned and refinished about 10 years ago but now it has sat. For some reason he left fuel inside to prevent rust so I had to drain out the rest of that. The old fuel was clear very orange fluid about 12 ounces. I have it all apart the sending unit and fuel line suction portion. The inside has an orange film, and some sticky brown gunk in places.

It seems I need to clean it out, some have said vinegar some have said muriatic acid, or gravel shaking around inside. Advice appreciated
5C9D71D0-8985-47E7-B2DC-EFF5DA4A07E7.jpeg
1A787C81-B3CF-4301-9AB6-ACA17132E450.jpeg

8B21A975-3198-489C-80FD-368416FBDF58.jpeg
 
Joined
Mar 3, 2014
Messages
388
Location
New Mexico
If it was me I’d probably rinse it out with a few gallons of fresh fuel, fill it, and run it. Make sure you have a spare fuel filter or two.

There are baffles and a flapper valve inside the tank. I wouldn’t want to dump gravel in there. Muriatic acid runs the risk of eating a hole in any thin metal you may have in the bottom of the tank.

This would be a good time to blow out your fuel lines and make sure they’re clear.

Sometimes good intentions have negative unintended consequences.
 

rghouse

SILVER Star
Joined
Mar 1, 2015
Messages
745
Location
Oroville, CA
I agree, honestly it’s not that bad in there. I got the gravel ready but just couldn’t go forward with it. I’ve got some vinegar in now and will try and swish it around some. I can poor it into a bucket too and see what flakes off.
 

Bear

SILVER Star
Joined
Nov 2, 2005
Messages
2,948
Location
California
Since you asked for advice, this is probably not the quick and easy answer you wanted to hear:

From experience, looking at the photos of the tank and the sender especially, I personally would-- and actually have-- had my tanks "boiled-out" at an old fashioned radiator shop and provided them with tank sealant which they use to coat the insides. This is likely what your dad did some time ago.

Sadly, you're back at square one because old, stale pump gas has sat in there far too long and/or the grit in there wasn't completely removed before re-coating the tank. I would also replace the sending unit, its gasket, clean the draw tube, add its new gasket, replace all rubber lines, new clamps, and blow-out the metal lines with some solvent and compressed air. Use a new filter(or two) and make certain your carb is cleaned of any and all varnish and fine particles. I'm sure you realize that if your entire fuel system isn't clean, you'll be fighting performance issues forever.

Once your tank is returned to you, don't let it sit a long time with pump gas in it, if you're not going to drive it regularly. You live in Kalifornia, and most likely use California RFG(reformulated gasoline) with a minimum of 10% ethanol--which draws in water(moisture) from the atmosphere and/or condenses with temp changes, that ultimately settles in the very bottom of the tank, slowly rusting it out. And don't count on fuel preserver additives to keep your pump gas fresh beyond a few months. If just on display, leave the tank empty and periodically pop the drain plug. If you need to keep gas in a dormant vehicle, replace/store any catalytic converter with a piece of straight exhaust pipe and find some airplane 100LL fuel to run it occasionally.

Is this politically correct? -- just look where you live and who's in charge. We rarely had a problem years ago. Either embrace what your government does for and to you, or fight like Hell ! Seems like an easy choice.
 
Joined
Oct 7, 2011
Messages
1,099
Location
Austin TX
Put some small chain, like dog leash chain in it along with lacquer thinner. Rattle the chain and lacquer as much as your muscles will allow, then dump it. Repeat as many times as you can until the dumped lacquer comes out fairly clean. Nothing will clean it better without damaging the finish on the insides. I have done this on maybe 20 gas tanks over the years and it always works. After you get it all clean, don't allow pump gas to sit in the tank unused for more than a couple of weeks. The ethanol attracts water and will either gum up the tank again, or rust it out. I only put Non-Ethanol gas in my 40 because I let it sit for long periods without driving it. As far as your sending unit goes, soak it in lacquer thinner and it will clean right up. Be sure to move the float arm while it soaks to get the contacts clean. If the float is neoprene or plastic, don't let it get in the solvent. Check the ohm readings on the sending unit before reinstalling it.
 

Users who are viewing this thread

Top Bottom