Atomic 4 engine and year old fuel question

[Ujin]

I have a late model Atomic 4 that has been well kept. However, the boat has sat for the past year with about 5 gallons of fuel in a plastic 20 gallon tank. I pulled a sample from the tank and the fuel has changed color and does give off that old gas odor.

I changed the secondary fuel filter and the water/fuel separator and added stabilizer to the remaining fuel in the tank.

The engine does currently run fine with a max run time of about about 30 minutes.

I am just wondering if I would be setting myself up for any internal engine damage or possibly a clogged carburetor if I ran the rest of the fuel through the engine?

I have read forum posts ranging from, 2-3 year old gas is okay just mix with fresh fuel or stabilizer to do not run old fuel under any circumstances.

Thanks for your opinions.

[rbk]

Get new fuel. Yes you can cause damage and it’s not worth 20 gallons of fuel. No amount of additives will make it good again.

[Jammer]

Ujin,


The main problem is that the stale gasoline will form precipitate (varnish) which clogs jets and needle valves. You will not create any internal engine problems.


If it were my boat, first thing in the spring, I would go motor back and forth while having some simple contingency plan if the engine stopped (like friends on the radio prepared to tow me in, or a situation where I could sail back, or whatever), until nearly all the gasoline is gone, then fill the tank with fresh gas.


Chances are it would be just fine, and burning up the old gas right away gets it burned up before it can throw any more varnish. The reactions that produce it are temperature sensitive, so it's not going to get worse while it's cold out, but you don't want to carry it through the summer.


The problem with siphoning and discarding the old gas is that doing so creates both a fire hazard while you're doing it and a disposal problem when you're done.


Opinions on the effectiveness of fuel stabilizers are all over the board. I don't use them. For winter motors (snowmobile, snowblower), I try to end the season with no gas and run the engine until the carb is empty. For summer motors (boat, lawnmower, bike) I just try to keep the fuel tank cool and try to be sure that the motor is refueled at least once during the summer, because the gasoline doesn't deteriorate in winter storage.

[roverhi]

Have run old trucks on gasoline that was well over a year in the tank, maybe even several years without a stabilizer. Biggest possible problem is gumming up the carburetor. The low compression A4 would probably run almost anything that will burn without harm. The reason they have survived so long and were so popular is that they would run on old fuel. If it's convenient wouldn't try and get another season but would drain the tank. On the other hand, if it will fire on that fuel, won't take long to burn it up and replace with new fuel, not try and mix the old with new. Use a gas stabilizer when you add fuel. Keeping a gas tank partially full encourages condensation but you may be better off keeping it that way so you don't end with old fuel in the tank. Don't know whether bugs live in gasoline like they do in diesel but using Biobor or other critter killer would be a good additive to keep your filters clean.

[rbk]

Yes you can cause damage with old gas although not likely in an old A4. With old gas additives like TEL, MTBE and TCP (pre ethanol, not that it wasn’t around but it was not available at pumps generally) is they didn’t absorb the humidity and render themselves useless in stabilizing the gasoline. Now you have an unstable fuel which can easily preignite causing piston damage, gasket, head damage etc. This becomes more apparent in high rpm 2 strokes and high compression high rpm 4 strokes ie motor bikes, outboards and almost every engine made in the last 35 years. And while your one ton on the Hwy cruising at 1500rmp won’t notice it, it might when you go to take off with a loaded trailer up a steep hill, or off the line with your sports car (which includes your kids driving your corolla thinking they’re in an F1)

[Ujin]

Thank you for the replies.

Looks like the best appraoch will be to remove the fuel. Although disposal is a an issue. I'm sure there is a resource to accommodate.

[rbk]

Get in touch with your local fire department, they will know where to dispose of it locally.

[Steve Bean]

Add the old gas to a partially full tank in a gas car or truck.

[Ujin]

Good call on the fire department. I'll definitely check with them. Thanks.

[carlheintz]

Ten years ago, I would have told you to just add some Sea Foam additive and you'd be set. Now, not so sure. The formulations of gasoline have changed a lot, and we don't know if yours is summer blend, winter blend, with ethanol or without. So, best to drain it and put new stuff in... and please, don't use the ethanol stuff, it's awful in a marine environment.

[boat driver]

Ujin-
If boat out of water- siphon old fuel into a barrel below boat either thru the engine draw or if you can get a hose into fill to bottom of tank.
Marina will have a facility or place to put fuel-
If in water gets more difficult.
If engine works now- get some beer and go run it down as far as practical- then mix new fuel into it as previously mentioned. Use sea foam or other additive to at least slow up or undo any varnish coming.
After this- add fuel as you utilize it- rather than fill tank in April and never use entire tank.
The risk of old fuel outweighs the short term humidity/ethanol absorbing from a slack tank adding five gallon increments over the same period.

[TommmD]

This has been very well covered, bu here's 2 cents having worked on an A4 for 10 years that came with a sailboat..

..If you have a starting problem, its the gas.
If you have a running problem its the gas....

Yes by all means check the points & plugs & upgrade to an electronic ignition.
But learn to rebuild the carb, bec in the end, its the gas.

Yes they are reliable when used continuously. Its the sitting around that does them in. Can lose prime, esp thru an electrical pump. Carbs varnish up, since they are found on older boats with years of sludge that gets loosened up w/ E10. Many installs don't have a fuel filter: Add a cartridge & an inline & don't be afraid to change them. Mine used a siphon from the tank & I added a hand prime inline which I wish I knew to do years earlier.

And since I didn't see it in other posts, find the Mpyer site online.
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good luck.

[Scott Berg]

As someone else noted, we burn it in an old pickup truck with a 3-1 ratio add 5 gallons of bad old gas and 15 of good gas each fill up. Cheaper than paying for disposal which can run $7US + per gallon!

[S/V Alchemy]

Originally Posted by rbk

Get new fuel. Yes you can cause damage and it’s not worth 20 gallons of fuel. No amount of additives will make it good again.

^^^This. Had I poured the correct amount of stabilizer into a sealed jerrycan filled up to reduce the air space and kept in a cool and a dark place, after a year I would consider it borderline. It's not gas now...it's varnish. The additives in modern gas do not help...it's meant to be used within a couple of months, ideally.

And yes, why risk a likely carb rebuild for nothing?

By contrast, I've been running old (but additive-free) diesel through my marine diesel with no issues. I run it through a Racor filter and get good results. But that's the difference between diesel and gasoline.

[S/V Alchemy]

Originally Posted by Scott Berg

As someone else noted, we burn it in an old pickup truck with a 3-1 ratio add 5 gallons of bad old gas and 15 of good gas each fill up. Cheaper than paying for disposal which can run $7US + per gallon!

The new gas is somewhat of a solvent to the old gas, so sure...wouldn't do it in a new car, mind you, but mixed 3:1 in chainsaws, lawn mowers and ATVs...sure.