Old gas in a tank.

So I put an old tank out of a parts jeep in my xj last week. We emptied it of gas and put some fresh in it and sloshed it around good to clean it but it appears there was or is some still there. Think varnish.... So in order to not pull my rear bumper and my newly installed gas tank skid is there anything I can put in the gas to help break this up and get it gone? It was suggested a cup of acetone.....

What kinda tank, steel or plastic ? How old was the gas ? How much is in there ?

I would put in a bottle of SeaFoam, or Techron and call it good. I bought a 99 that sat under a tree for 2 years without a gas cap. After I fixed it, I drove to the gas station for some fresh gas.

Tim_MN said:

What kinda tank, steel or plastic ? How old was the gas ? How much is in there ?

I would put in a bottle of SeaFoam, or Techron and call it good. I bought a 99 that sat under a tree for 2 years without a gas cap. After I fixed it, I drove to the gas station for some fresh gas.

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Steel tank. IDK how old it was. We dumped all the old out and even cleaned the tank with new before we installed it but the jeep ran rough this weekend wheeling. I'm guessing the tank had residue in it and the new gas it breaking it down and its causing problems.

Year model? Interior or exterior fuel filter. If external, replace it.

old_man said:

Year model? Interior or exterior fuel filter. If external, replace it.

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if you dumped out the old, flushed it with some new and then filled it with new after the install, the issue isnt old gas.
you might have loosened up some crud that is plugging your filter.
you didnt say if you used your existing pump or the old one from the donor tank.
i'm thinking more along the lines of an electrical issue. can you elaborate on the running rough?

old_man said:

Year model? Interior or exterior fuel filter. If external, replace it.

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Forgot that detail: My trail rig: 94 xj 4.0L AW4 with external filter. I just bought a new WIX to replace it and some seafom.

sidriptide said:

if you dumped out the old, flushed it with some new and then filled it with new after the install, the issue isnt old gas.
you might have loosened up some crud that is plugging your filter.
you didnt say if you used your existing pump or the old one from the donor tank.
i'm thinking more along the lines of an electrical issue. can you elaborate on the running rough?

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Used my existing sender and pump. It was backfiring and loosing power like a misfire or clogged injector and would make all kinds of noises. I feel certain it's a fuel issue. The tank came out of a parts jeep I have had for a couple years. IDK how long this jeep sat before I got it. The gas that was in was varnish. I think it was also coated on the inside of the tank and putting new gas in it has loosened it up. Looking for something to loosen it up more. Acetone was suggested but thought I'd see if any of you have ever had this happen before.

Sounds like you already cleaned it pretty well, maybe some ethanol gelatin broke loose or something but too late for all that. Just dump a bottle of Lucas fuel system cleaner in there and forget about it. Maybe some octane booster.

seafoam.

a whole can in the tank.

87manche said:

seafoam.

a whole can in the tank.

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Going to try that after work. New filter with that or after I run that tank dry as I can get it?

Add Red Line fuel system cleaner to the gas, make it double strength. Let it sit for a couple of days and then the varnish should wipe right off. I just did this recently and it worked great. It seems to have completely dissolved everything. I took the old fuel / cleaner (5 gal.) and added it to my sons gas tank with no ill effects.

Acetone is a dry'er, often used instead of the brand 'Heet', and/or others, and cheaper, i.e., one buys a gallon at the hardware store, using a turkey baster, (for example), in order to insert said prior to fill-up.

An ounce, or two is often used at fill-up in order to dry up any small amounts of gasoline that has an extra amount of water going through the station pump, and/or condensation dripping from the interior ceiling of tank, etc. I often do the above, and find better performance, and mileage results.

I do use SeaFoam every other fill-up, i.e., half a can at a time.

I also use an ounce of 2-stroke oil on each fill-up.., straight from the plastic bottle.., for upper cylinder lubrication.

Small amounts of the above liquids seem to work best as for regular maintenance.., but not used excessively.

Your varnish issue seems to require a couple of extra fuel filter changes during your process of eliminating the last traces of varnish whilst using bottles of magic.

Yea I dumped a bottle of seafoam in her last night and seemed to run better. I'll run this tank dry and change the filter and fill it back up with another can. Really will not be able to tell if it works until I can get it out in the woods and under a load. She misbehaved the worse when I was having trouble on big rocks.....

Second on the Redline Fuel System Cleaner...and I recommend a bottle of it every oil change or 3k miles

Also try "Berryman's chemtool B12".

It's what I use in my fuel injector cleaning tool. The stuff is so strong, it doesn't need to be mixed with gasoline. Seafoam needs to be mixed w/fuel to run through the tool.

(I'm not saying that Seafoam is a bad product.)

Berryman's B12 is powerful stuff, just washes the varnish off

Ghost said:

Yea I dumped a bottle of seafoam in her last night and seemed to run better. I'll run this tank dry and change the filter and fill it back up with another can. Really will not be able to tell if it works until I can get it out in the woods and under a load. She misbehaved the worse when I was having trouble on big rocks.....

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you, trouble in rocks? unpossible.

yes to the fuel filter change after you run the tank. it's gonna dissolve a bunch of stuff that turns to nasty in the filter.