Rust in the gas tank.....

Joined
Sep 26, 2021
Messages
179
Location
Houston Texas
My son in law was given a generator a Tri fuel Firman - 9400 watts startup power on gas - the prior owner used it once with gasoline about a year ago and once on natural gas since then before getting a whole house unit.


He ran the unit until it stalled - out of gasoline - except there was about 1/4 inch of gasoline left in the bottom - and now it looks rusty.

I told my SIL I would try and see what I can do to save it -

1. Drain the last bit of old rusty gas - is a first step -

Then what??

Dump some oil in the tank and then drain it out?

Then flush it with some fresh gas?

Then see what I can see?

any ideas???
 
Last edited:
How hard to remove the tank? If you can remove it, then you could drop in ball bearings or the like, give it a good shake, and work at removing any rust. Good flush with a bit of fresh gas. Then: can you add an inline filter?

I'm guessing many a gas tank has run for quite some time with some amount of rust on the bottom. It's when it gets loose and plugs up a filter (or worse, the carb) that it causes problems.
 
How hard to remove the tank? If you can remove it, then you could drop in ball bearings or the like, give it a good shake, and work at removing any rust. Good flush with a bit of fresh gas. Then: can you add an inline filter?

I'm guessing many a gas tank has run for quite some time with some amount of rust on the bottom. It's when it gets loose and plugs up a filter (or worse, the carb) that it causes problems.

Worth looking at -

My Wen PowerPro Chinese noisemaker purchased in 2007 - used in 2009 and then again in maybe 2015 has ZERO rust in the tank.

I drained it - every drop before storage.

#1 reason my generator will not start after being in storage is fuel related - you can't leave gasoline in them for a year or 10 and expect it to not be a problem.
 
What is the odds it has a dead battery? 100%!!!!!!!!!!!!!

Can a 66 year old man in reasonable shape pull start a 439cc OHV engine that has not been started for over a year?
 
how much and how available is it simply to buy and install a new tank?

Consider what is your time worth... MANY times, just because I spent too much time, effort and what turned out to be wasted $ when I should have just replaced.... What to invest in repair vs replace???? That's a tough call)
 
I've derusted a good number of motorcycle gas tanks. First thing, is remove it, then drain. Fashion some robust plugs for all the openings. An aluminum plate with inner tube, or expandable plugs from the hardware store are worth investigating.

You will first have to remove all the old gasoline varnish first. Carburetor cleaner can help. To derust, I use phosphoric acid. Kleen Strip Etch and Prep from Home Depot. Or, Evaporust. After all the rust is gone, wash with water, and get ready to dump that out FAST, and then spray down the inside with a heavy dose of WD-40. Some people use diesel fuel for this last step. Doesn't matter, you just want to coat the tank before it flash rusts.
 
how much and how available is it simply to buy and install a new tank?

Consider what is your time worth... MANY times, just because I spent too much time, effort and what turned out to be wasted $ when I should have just replaced.... What to invest in repair vs replace???? That's a tough call)
I did a few searches and found nothing - I will need to contact Firman - other similar tanks run about $100.
 
Take the tank off, throw some chains and muriatic acid in there and roll it around. It'll come clean in no time.

Then use a tank sealer.
 
My son in law was given a generator a Tri fuel Firman - 9400 watts startup power on gas - the prior owner used it once with gasoline about a year ago and once on natural gas since then before getting a whole house unit.


He ran the unit until it stalled - out of gasoline - except there was about 1/4 inch of gasoline left in the bottom - and now it looks rusty.

I told my SIL I would try and see what I can do to save it -

1. Drain the last bit of old rusty gas - is a first step -

Then what??

Dump some oil in the tank and then drain it out?

Then flush it with some fresh gas?

Then see what I can see?

any ideas???
Is the tank rust or just rust in the gas. If the tank is rusty you need to buy a gas tank coating kit and go through that process. Or buy a new tank.

If just rusty gas I would pull the gas line and drain into a container a the flush with a QT is cheap alcohol.
 
If the tank is fully and properly derusted, there is no reason to coat it. Only if there are deep pits, where you can't get all the rust out, would a liner be justified.
 
I assumed the prior owner didn’t drain the gas.

I pulled the fuel line and tilted the generator and no gas comes out.

I added a little fuel stabilizer- about a cup and a cup of liquid drained out.

This is a very poor design and enough of an issue I would never buy a Firman generator.

My Honda and Wen both have a petcock that can be easily removed so 99.999999% of the fuel will drain.
 
It also looks like a giant pain to remove the gas tank. Not like most where you just remove 4 bolts.
 
I may have discovered a way to drain the fuel tank.

The fuel line coming from the nipple in the bottom of the tank - may be a fuel filter.

I am hoping it unscrews from the tank.

I think it is a filter because I see all sorts of particles floating in the tank - but non of them come out from the fuel line. So something is filtering them.

I can't imagine anyone would install a fuel filter that could not be removed and cleaned. The first time I looked at it is seemed round but closer examination shows it has two flat spots - like to put a wrench on.
 
Please post a follow up. I have 2 Predators with metal tanks. Previous experience with metal tanks rusting when stored empty has me keeping them full. I use Stabil blue and tag the tank with the date of the fill. I test run them every so often to make sure they will start. Last week, I drained the Snow blower's 2 1/2 yr old gas and replaced it with fresh. Stale fuel is easy to remedy,rusted tanks aren't.
 
Back
Top