Rust in Gas Tank!

I have an 1986 Puch Maxi. It has sat for about 10 years unused at my mothers house. I have recently started to try and get it running. I checked for spark, and it has good spark. I took the carb apart and soaked it in carb cleaner and it looks good. The only thing that remains to do (it seems) is get gas flowing through the fuel line. I peered down into the tank and there seems to be a nice coating of flaky rust inside. No gas comes out when the petcock is on reserve and only a trickle/drip comes out with the valve on. There must be quite a bit of sediment down in the bottom of the tank.

Does anyone have an easy recommendation for cleaning the rust out of the tank? I've looked into the Kreem procedure, but that would require taking off the engine and most of the components so that the tank/frame is light enough to manipulate to remove the rust, etch and coat. Way, way too much work for this shade tree mechanic. I basically want to get as much of it off as possible with maybe some miracle solvent in the tank but I don't know of one that exists. I have already spliced in an el-cheapo inline fuel filter to catch the remnants.

Help Please!

Thanks

Re: Rust in Gas Tank!

Do a "search" on this topic, covered many times. I have used Naval Jelly which worked fine.

Greg

Re: Rust in Gas Tank!

Ron Brown /

Phil,

Here is my standard treatise on gas tank cleaning. You will find this and other ideas if you search the forum.

These instructions were originally written for someone with a "Tank in frame" moped so if you have a removable tank, some operations are a lot easier.

There have been posts on the forum refering to the use of gravel, BBs, nuts and bolts and other abrasive odds and ends which can be shaken up in the tank.

The only kit I am aware of for doing this is a Kreem kit, it is quite expensive but very good. It is difficult to use on a tank in frame ped.

I have used muriatic and phosphoric acid. I prefer phosphoric because it does not promote rust. Brand name cleaners have been mentioned on the forum which contain phosphoric acis such as CLR and Naval Jelly.

I would stick with the acid only approach, as opposed to buying a Kreem kit which coats the tank. If your tank is excessively rusted, to the point where gas is seeping through the rusty spots, go to a motorcycle shop, buy a Kreem kit and follow the directions. The coating will seal small holes.

Pick up a gallon of Phosphoric acid and a bottle of "dry gas".

Most buisinesses using large stainless steel vessels use Phosphoric acid. Dairy farmers, dairy products, brewerys etc. Posibly you could call one, or just stop by, it is cheap and they may just give you some. I have also heard that it is sold in Meijers pool section so I suppose other pool supply stores would have it. "Dry gas" is available at auto parts and gas stations for removing water from your fuel system.

Whem you use it, you are going to have to figure out how to get it back out of the tank safely. Typically, with a removable tank, you can just duct tape over the holes and dump it by removing the tape. You must remove the petcock and removing the gas cap is a good idea as it has a vent hole which can leak acid.

If the petcock scews into a threaded hole in the tank, maybe you can find a brass nipple that will fit the thread and allow you to drain the acid safely. If you have no choice but tape, remember that a running hose is your best defense against disaster.

For all of the following, keep a garden hose available and turned on. Wear old clothes, there is a good chance they will become religious, as in holey. Work outside, away from anything which could get splashed. When rinsing, use a lot of low pressure water, high pressure will send acid to places where it may do damage before you find it.

Dilute some acid in a plastic container and test it with a piece of rusty steel. You want it to remove the rust in about ten minutes but you are not looking for a violent reaction.

Remove the petcock and plug the hole with something appropriate, good duct tape usually works. Remove the gas cap if possible, if not, cover the hole with saran wrap before closing the cap to keep the vents from filling with acid.

Pour enough diluted acid in the tank to almost fill it. Seal the filler with tape or the cap/saran wrap and slosh the acid so that it is cleaning the top side of the tank. Just rocking the bike will do this. Keep an eye open for leaks and rinse off any acid you see immediately with a slow hose. Keep sloshing every minute or so until your time is up as determined by the test above, then slosh and wait five minutes more.

I am not sure how you are going to drain the tank but if you have not figured out a drain tube, lean the ped so most of the acid will fall straight to the ground and keep a sready flow of water on the hose to rinse any parts of the ped which get splashed.

Btw, letting the acid run into the ground in your yard is not an ecological disaster. Many plants prefer acidic soil. Don't let your pets get near it, dilute it a lot and don't dump it all in one place, especially not at the base of a tree.

Check the inside of the tank to make sure you do not need another application.

Using a rinse and slosh tecnique, get rid of all the acid in the gas tank then dry off the ped. If you have an air line, blow out the tank. If not, dry it as well as you can with rags, paper towels, hair dryer etc. Then replace the petcock and pour a bottle of "dry gas" into the tank and close the lid. Slosh this around for a few minutes to mix with any remaining water trapped in the tank seams, then drain it out.

Add gas and ped away.

Re: Rust in Gas Tank!

I tried a search using gas tank rust and got nothing

Re: Rust in Gas Tank!

Thanks! That sounds along the lines of what I was hoping for. I'll just have to get my hands on some phosphoric acid.

Re: Rust in Gas Tank!

aha, the key seems to be to search past the last 30 days;) thanks:)

Re: Rust in Gas Tank!

Ron Brown /

Phil,

This is a computer, it does EXACTLY what you tell it too, almost never what you want.

Try just a word or two like acid or rust or gas tank.

Ron

Re: Rust in Gas Tank!

ok I read some past entries and this is what I have decied to try.

Remove the petcock. Duct tape the hole (maybe I should buy a brass plug). Fill the tank with a mixture of very hot water and CLR. (I should definately test a rusty piece of metal to determine the concentration and duration required to remove the rust). Take the moped to a 'do yourself car wash' with the high pressure hot rinse hose. Blast the crap out of the inside of the tank. Fill the tank with some dry gas, slosh it around and drain, repeat maybe again. Put petcock back on (WILL I NEED TO USE A PIPE DOPE AFTER THIS ACID HAS LOOSENED THINGS UP A BIT AT THE THREADED CONNECTION?). Attach the fuel line to the carb with an in-line filter in place. Pour in a fresh 50:1 gas/oil mixture and fire her up. Does this sound good? The rust seems relatively light, I mean it's not pitted just a little flaky.

Thank you Ron and everyone for the great input!

I'll let you know how it works out

Use teflon tape instead.

Pipe dope is for things you won't need to disassemble or very heavy duty uses.Use teflon tape.You'll be happy later!(:^)

Re: Rust in Gas Tank!

Ron Brown /

Phil,

This sounds good except for the high pressure hose, I would be afraid of splashing the acid about. I suppose if you drain it out before squirting it, the mixture will be dilute enough to not matter.

Wear glasses, old clothes and go for it..

Ron

Re: Use teflon tape instead.

Ron Brown /

Phil,

Don is right about the teflon tape if your petcock seals by the threads. If it is supposed to have a sealing washer or o-ring, you should replace it.

Ron

Re: Rust in Gas Tank!

Here's what you do. Take the tank of and put a couple cups of bb's or gravel or whatever you can get your hands on. If it will fit inside a gallon bucket, wrap it in foam and close the bucket. Take it to a local paint shop and have them shake it for a while. Don't laugh, it works but I used a friends shaker.

Re: Rust in Gas Tank!

Bill,I ain't laughin' but I just haven't seen very many gas tanks that will fit inside a gallon bucket.So I guess the tank can stick way out of the can and it's alright?I'm trying to visualize this,but I haven't used a paint shaker in a while.Sounds like a good idea to mechanically remove rust.

Re: Rust in Gas Tank!

Ron Brown /

I like this one too. I think some of the little jap minibikes had tanks this small. I can just see the look on the face of the paint shop guy. : )

Phil may have a somewhat larger problem fitting his complete frame in a gallon can.

Ron

Jumpin' Jacks!

Hey,Ron!Maybe Phil could strap it to a 90# jackhammer and tear out some concrete while he's cleanin his tank out at the same time.He could rig the throttle control up to the air valve and have a `smashing good time' and all that,what?HeHe!

Re: Rust in Gas Tank!

I meant 5 gallon paint bucket. It sounds like it is ready

to jump out of the machine, just hold your ears.

Re: Rust in Gas Tank!

unfortunately the tank is part of the frame and I'll just have to get by with sloshing it with acid and pressure washing the inside.

I suppose I could hang the front end off the ground with an old garage door spring I have, tie it to a cross beam in my garage and push the moped up and down really fast. I could then put some abrasive item inside the tank, maybe a piece of dog chain. Very large springs in tension frighten me though, so I probably will try the slosh/wash method first.

Re: Rust in Gas Tank!

Phil,when you say the word `slosh' and you're talking in relation to acid,you scare me.You only got 2 eyes,so be ultra careful.Keep that water hose where you can find it by feeling for it.When you splash acid in your eyes,you can't see worth a hoot.Goggles and gloves,man!

Re: Rust in Gas Tank!

Ron Brown /

Phil,

When you use acid, you don't need a lot of agitation, mild "sloshing" is enough. You do have to do as Don said and keep the hose handy. You may build pressure in the tank which should just loosen the duct tape over the filler hole, but you should be ready to rinse off any spillage.

Do this outside, not in the garage.

Ron

Re: Rust in Gas Tank!

use MURIATIC ACID, which you can buy at your local hardware store.

Re: Rust in Gas Tank!

Ron Brown /

Toehead,

Muriatic acid does a fine job of removing rust, I have used it many times. It also does a great job of causing rust.

Due to some chemical reaction, which is beyond my knowledge, something in phosphoric acid, binds to the clean steel surface and retards rusting. Muriatic acid does the opposite, in fact, the clean surface will rust before you can get it dry.

Ron

Gas Tank Update!!

Well I finally got a chance to clean the tank.

First I filled the tank up with a gas oil mix likea week before, to maybe loosen things up a bit.

I took of the fuel valve and drained the gas. I then threaded on a pipe cap and filed the tank up to the top with full concentration. Calcium, lime & rust remover from ZEP. I put the gas cap on (which was also pretty rusty on the inside) and then stood over the bike on the pedals and rocked the bike back and forth. I did this for about 1/2 hour. To my amasement the rust just melted away.

I drained the chemicals into a bucket using a funnel. Then I attached a drain line I made to the threaded nipple where the fuel valve goes. I turned on the garden hose flushed out the tank really good. After the tank was devoid of sludge I poured the tank to the top with very hot water (while holding the drain high enough so water wouldn't drain out), shook it around, drained it and poured some more hot water straight through. I then used a blow dryer to dry the tank out. I then hosed the gas cap, poured dry gas all over it, and soaked it in gas oil mix for a bit.

Well I tried to clean the varnish off the old fuel valve.filter but it was pretty much shot. I ordered a new one for $20 from themopedjunkyard.com, put it on, put an inline filter between the fuel valve and carb, and she fired right up and runs beautifully.

In trying to get the headlight to work I noticed that there is this black rectangular piece attached to the fork, behind the headlight housing. This rectangular piece has a yellow wire coming directly out of it that isn't connected to anything. I got the headlight to work (bulb just needed to be repositioned) and the brake light works, however the running light doesn't work (tail light) and it's hard to tell if the speedo light is working.

What is this black rectangular thingy with the wire coming out of it? Where should the wire connect to? Does anyone know what I am talking about?

I have a 86 Puch Maxi Sport 2 Speed

Thanks to everyone for the help with the tank rust!

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