Pond Boss Forums Thread Like Summary - Rust in Small Engine Gas Tank

Just pulled out my old 2" trash pump to put it to work for the new year. The rust in the gas tank finally got well established, compared to its previous toehold.

The pump is an inexpensive Champion 4.0 HP pump that is probably 12-15 years old. (Maybe cost $200 on sale at Tractor Supply Co.? Similar new pump is probably now around $350.)

I generally do good maintenance and winterizing on my power tools, but I am NOT a small engine repair guy.

Questions for the experts:

Should I just soak the tank in some of the rust cleaning solutions and see how it goes? Is a weak acid treatment (like 50:50 vinegar) a better rust cleaning solution?

I assume I also need to clean the carburetor. Easy enough, especially if I can find a youtoob video?

If the small fixes don't work, is it time to buy a new pump? Or could I install a new gas tank (slightly rigged if necessary)?

The pump is pretty old by years, but only has a few hundred (or fewer) hours on it.

Any advice before I start tinkering would be greatly appreciated. Thanks, FishinRod.

One big no-no that I've figured out is DON'T use gas that has any ethanol in it. Ethanol attracts water, and gums up a bunch of stuff. Just say NO.

Rod, you got really good advice, so I'll try not to screw it up.

As varnish was mentioned mentioned later, my uncle had a small engine shop and he used acetone and nuts and bolts to clean out gas tanks.The nuts and bolts beat the loose rust off, and the acetone took care of the varnish. He would just walk by and shake it ever hour or so. If the liner mentioned is good, then removing the lose rust prior should help.

My motorcycle and outdoor power shops use Ethanol Shield for all gases, so that's what I use. Never once had a moisture problem with stored 100% gas. The fuller the tank, the less chance of humidity issues.

For sticks, and other 2 stock engines, Red Armor is about the best oil I can find. It's a little more expensive, but it actually does clean existing and reduce new piston and cylinder carbon. Voodoo at it's best. Echo shops should have it.

Look up frog lube.

Al, I'm going to look for the Rend Armor oil you mentioned. I was using a synthetic 2-stroke oil but I only have enough left to treat 2 gallons. The local marina said no matter what gas I buy, to treat it with an ethanol stabilizer because they've seen too many cases of "non-ethanol" gas have traces of ethanol in it.

Acetone to dissolve the varnish. Popping the bowl is iffy just to take a look if nothing is wrong. If you tear the gasket, where will you get a new one?

Buy this: https://www.eastwood.com/gas-tank-sealer-kits-eastwood-gas-tank-sealer.html

Take the tank off and follow the directions.

See if it runs after you put fresh fuel in it after you fix the tank. If it doesn't, I bet it'd cost you $20-$25 to buy a new carb on amazon with gaskets.

Oh, replace all the rubber lines on it while the tank is off - they get old and might have hairline cracks in them.

Tested the fuel tank overnight, and it has the tiniest pinhole leak. So I figured I should call the manufacturer to weigh replacement versus repair.

Wow, got excellent customer service from Champion.

The service lady had to put me on hold for about 8" to find my part number since I have a discontinued model pump.

She had to get the supervisor to help, but they said they found it and still have it in inventory for the princely sum of $14.37. I asked her to hold so I could grab a credit card, and she said not to. Her supervisor thought they took a little to long for "good" customer support. They are just going to ship me a replacement tank at no cost.

I sure hope they did get the right one! If not, I may just JB Weld it in place and connect the fuel line.

Thanks for all of the help. I hope the carb is still in decent shape.

F Rod, you've been here on the forum long enough to know and remember our favorite small engine mechanic spkplg. I believe he still follows the forum, just chooses not to post.
I can imagine he may be smiling and nodding that you are on the right track with your repair.
One of my strongest hobbies is also small engine repair. I'm particularly enamored by 2 strokes, with chain saws topping the list.
BTW, ole' sparky could, and hopefully still does, grow a pond full of dandy HBG.

FishinRod, glad to hear we have another saw junkie on here.
I rarely buy a saw new, and never buy a used one. Why not? Because nearly everywhere I go, when people find out I love and work on saws, they pull one or two out and say, "Would you like this? I can't start it.Or, it won't keep running." etc.
Just last weekend we drove all the way to Tucson to pick up an Australian shepherd rescue.The rescue dad gave me a perfectly good Echo 340 climbing saw that wouldn't start. Turns out the location of the fuel tank and the bar oil tank are reversed on that model. So, of course, he accidentally filled the fuel tank with oil and vice versa. Easy enough mistake. Even with 52 years experience making money running chainsaws, I nearly did the same. I caught the little chain link icon on the side of the saw by the filler cap at the last minute.

Years ago in my timber felling days in Oregon and Idaho, I would invariably have a new saw hopped up, including porting, timing advance, gutting and dual porting the muffler, shaving the piston's skirt, etc. Any saw I get these days gets the muffler opened up, the adjustment limiters changed or removed from the carb, the cylinder gasket removed, the rpm limited ignition coil swapped out, maybe something else if necessary. I don't even consider the warranty. The boost in performance is so noticeable and immediate that trudging through the interminable warranty period would be...BORING!

I've turned my 3 Echo saws, a 271, a 400, and the 340, into much more than they were when new. They run cooler and last longer with these mods. I'd be more than glad to discuss at length the improvements I've seen on many, many Stihls, Husqvarnas, Makita/Dolmar, Hitachi, the Echos, Jonsereds, and junky saws I won't name.

The Chainsaw forum on arboristsite.com is a fascinating source of info, opinion, argument, bias, and more about trees, saws, logging, on and on. It is not run so politely as is this PondBoss forum, but doesn't digress into despicable behavior as do some sites. BTW, esshup is on there.

When cutting those over sized, wet logs, try pulling your bar out of the cut every 30 seconds or so, rev it momentarily to get a little more bar oil on the chain, then resume cutting. That reminds me of belling big skanky cottonwoods and Siberian elms that have water running out of the initial felling cut. And, we were felling a stand of 4' to 5' diameter white firs in Oregon some years ago. Our first cut had to be partially made, then the saw bar pulled out while up to 10 gallons of liquid drained from that cut. If the sawyer didn't wait for the drainage, he'd be soaking wet from the waist on down. Those big white fir culls weren't called piss firs for nothing!

And, thanks for the thread hijack! HAHAHA!

Who, me??? LOL

A CS-340? Hmmm. If it's for sale, let me know. I have had one for pushing 21 years now and it wouldn't have one to have for spare parts. (You know how that is).

I don't have CAD (Chainsaw Acquisition DIsorder), I only have 3 saws. SC-340, Dolmar PS-5100s and a Dolmar 7900. Both the 5100 and 7900 run .050" 3/8" semi-chisel. So does the 340, but it's a LP chain.

gehajake, thanks for pointing out an obvious stupid thing I do that is easy to avoid!


I usually just fill a 1 gal or 2 gal can. Didn't think about the ethanol crap in the hose. I think I will start purging the line into my truck with the first bit of gas!