Nasty gas tank

[gerhed]

Ok kids, I'm looking for some advice. My old 83 has bad gas in it. I syphoned out as much as I could. I had put about 10 gallons in on what I thought was a dry tank, but I guess there was a gallon of so of bad in there. Well, the new gas went bad in about two weeks, and boys, I mean bad. So, short of dropping the tank, and possibly replacing it, what can I do here? Can I just put fresh gas in and drive it out a couple times and stop this, or is a new tank about my only option?

 

[PrairieDrifter]

Ok kids, I'm looking for some advice. My old 83 has bad gas in it. I syphoned out as much as I could. I had put about 10 gallons in on what I thought was a dry tank, but I guess there was a gallon of so of bad in there. Well, the new gas went bad in about two weeks, and boys, I mean bad. So, short of dropping the tank, and possibly replacing it, what can I do here? Can I just put fresh gas in and drive it out a couple times and stop this, or is a new tank about my only option?

Depends what it looks like coming out. Pull as much of the old gas out then put some fresh in and go drive the rest out.

Would maybe do it a couple times. Just to make sure it's all out.

If it looks rusty, you'll be miles ahead just getting a new tank and sending unit.

 

[gerhed]

It ain't rusty, just very yellow and smells of lacquer. Was causing a stutter, maybe. Old quadrajet had issues. Anywho, yeah fresh gas, new carb, drive the **** out of it. Fingers crossed, lol.

 

[gerhed]

Whew, whole shop smells like somebody been finishing furniture down here. No wonder it was missing, lol

 

[TotalyHucked]

Throw some B12 Chemtool or other fuel system cleaner in for the next 2-3 tanks too, that'll help clean all that varnish out of there

 

[PrairieDrifter]

Maybe some marvel mystery oil too. Don't stick any valves!

 

[Grit dog]

Seafoam is supposed to dissolve varnish as well.
Guess the question is can you dissolve it and the gas still be good enough to run it? Not something I have the answer to.
Best way imo would be to drop the tank and clean it out, which I understand trying to avoid if everything works fine with the sender and it’s not rusted out or leaking.
Sort of a gamble to keep throwing $ at gas if you have to siphon it back out.
I’ve not dealt with a car with a varnished tank but an old snomachine (more prone to running poor, detonating etc than a 4s engine imo). Don’t think the gas ever dissolved the varnish over several tanks. Because I kept picking up flakes of it in the fuel filter for an entire winter.

 

[90Supurban]

Might want to travel with a couple of extra inline fuel filters for a while if you're breaking that varnish free. Reminds me of a Roadkill episode where they recovered some vehicle that had a known nasty fuel system. They stuck about 4 inline fuel filters in the system in series, yanking the first one in line each time the car started to get starved of fuel.

 

[75gmck25]

On Roadkill TV show they always put at least two of the large diameter metal-body fuel filters inline before the fuel pump when they pull a junked car out of the yard. If the engine starts to starve for fuel they remove the filter closest to the tank and replace it with a section of hose. If it happens again, then they replace both filters.

 

[Snoots]

Pull the tank and completely drain it. Take it to a rediator shop and they can hot tank and pressure test it. Some shops can even put a sealer in and paint it for you.

 

[gerhed]

Wow, thanks for all the advice guys.

So here's what I did. I forgot to mention that I had put some, well ok, a lot, of Lucas fuel treatment and injector cleaner into the tank along with some octane booster when I first put fresh fuel in it. I think it may have dissolved a bunch of varnish into the fuel. Syphoned it out. Grabbed a 5 gallon can of fresh gas, put it in the bed and took off down the road til it ran completely dry and won't even start. Put in the fresh gas and it seems to be doing better. The smell is gone anyway and it's running very smooth.

 

[gerhed]

And, I think I got a wheel bearing going out, lol. Passenger side hub is warm and something was growling when I got speed up for a couple miles. For another post, lol.

 

[Grit dog]

Wow, thanks for all the advice guys.

So here's what I did. I forgot to mention that I had put some, well ok, a lot, of Lucas fuel treatment and injector cleaner into the tank along with some octane booster when I first put fresh fuel in it. I think it may have dissolved a bunch of varnish into the fuel. Syphoned it out. Grabbed a 5 gallon can of fresh gas, put it in the bed and took off down the road til it ran completely dry and won't even start. Put in the fresh gas and it seems to be doing better. The smell is gone anyway and it's running very smooth.

Lol, yeah forgot to mention. I interpreted your post as is it was so bad it was making gas go bad enough to not run.
As long as it doesn’t plug up the sock on the fuel pickup which it hasn’t yet, you should be able to dissolve it and move on without dropping the tank.

 

[Craig Nedrow]

Ahh the easy fix…

 

[Grit dog]

And although clear plastic filters aren’t recommended for long term use I’d add one, preferably in a convenient spot. (If your truck still has the OE hardline from fp to carb I wouldn’t cut it)
Then you can see and catch what’s coming out of the tank and quickly replace the filter if it’s inhaling varnish flakes. (It won’t unless the sock on the fuel pickup in the tank is off or also degraded.)