Hi, Should a petrol engine be drained of fuel when finished running for the day as nitro engines are or should some fuel be left in the tank ? Cheers, Mark.C.

Yes they should in my opinion, if the gas evaporates it leaves behind "varnish", and the oil mix. I always drain my gassers and run the gas out of the engines.

Doesn't matter. When the gas evaporates it leaves two stroke oil in the engine, not "varnish". Unless you're using a castor based oil, in which case you'll have more varnish to worry about just from running the engine.

The oil is both a lubricant and a protectant. You can run an engine and put it away for several years with only placing a bag around the engine to seal in the residual oil. When it comes out of the bag the engine will be just fine a few years later. I've got some engines here (more than 20) that have been sitting in a box for years after their last runs. All of them still have a adequate oil film in them after their last runs. Don't even have bags on those...

What is that nasty stuff that straight gasoline leaves behind when it evaporates? I don't know I just prefer not to have it inside my carburetors.

You can drag your old weedeater out after sitting all winter with gas in the tank and carb..Start it right up....Same goes for a chainsaw...Worst case would be a new carb diaphragm kit, about $5....

Additives and perhaps some benezene residue. Comes right off the next time it sees new gas.

Yes, if you're lucky. I have cleaned or rebuilt many a chainsaw / weedeater carburetor after sitting all winter, now I store them dry. I can can tell where this thread is going co I'll leave Y'all to it.

With the Ethanol in American gas these days (Thank you EPA!!) I prefer it never sit more than a week, especially in my carb. If my riding lawnmower sits for more than a few weeks (winter) with fuel in the system it completely gums the fuel pump and I have to let it soak in carb cleaner. Same go's for the fuel lines. I had to replace every inch of fuel line on it late last year because it quit running one day. Pulled the tank off and the inner liner of the fuel line had melted and basically turned into a thick black melted rubber/tar substance shutting off the fuel supply. I need to buy stock in Sta-Bil as it's now added to every fuel can I own to minimize the damage of Ethanol.

I know there are pro and cons to this, I never remove the fuel from mine and some set for months, another reason not to is the fuel lines will harden quicker with no fuel in the tank.

I leave the gas in mine. I've left it in the tank for 2 months over the winter and never had a problem.

I am in the military and going away for 2 to 3 months at a time and other than a little longer priming session Mine have been great to leave gas in them. I just shut them down after the last flight and take home to store! Always love that first flight when I get home

Thanks,Mark.C.

Thanks, Mark.C.

when I was riding alot of moto-x we would leave the oil mix gas in the bikes for extended periods with no problems, but when I would work on restoring a older street bike or classic car(used to be quite the gear head) we would encounter a situation we called the green death.

when fuel would sit in a carb a green film would form and all the seals would go bad including the carb jets, sometimes a rebuild took care of it sometimes they were too far gone to repair.
it all depended on how long the fuel would sit.

here in CA I would run the fuel out of my engines no matter what type,because of the alcohol content, seems like the oil would prevent the death, over pure gas, better safe than sorry,not sure if aussie gas has eny methanol in it you would think so.

Been down this road before. I believe it depends on your part of the country and the gas formulation there what the effects on a carb is after long periods of storage. Here in Iowa (and MN as we have property there too) we've had ethanol mixed gas for years and I've never had a problem with leaving it in a tank for long periods. I really don't believe it is the ethanol in the gas that is causing the problems but it is the overall formulation of the gas that is the issue. Gas is not the same everywhere in the country. Just my opinion but many posts on various forums seem to support this.

<div>If you plan not to run your 2 stroke engine for say 2-3 months just mix a small amount od FRESH gas with additive called fuel stabil. Then run the engine long enough to get the new fuel mix through the engine. Rev it up wide open and kill it with full choke on. This pulls a lot of the gas -oil into the crankase. There it will keep everything from rusting and keep the seals flexible. I have a chainsaw nearly 20 years old and done this after every time I used it...at the last run of the day. That saw has never needed a carb part. I did replace the in tank fuel line &amp; felt filter...just as a maitainence thing. I read it was the thing to do on a Klotz oil can years ago. Works very good. Capt,n
I added photo of wood the same saw cut in 3 days...by my son-in law!</div>

Same back ground with bikes and have seen this green death, have 1985 suz gsx-r 750 which has been sitting for 10 years, hopfuly this has'nt GD. Back to planes, was only curios when leaving the fuel for a few days or so. Thanks for help,Mark.C.

Sounds good,Cheers,Mark.C.

Thanks, Don't know if the fuel has ethanol here in Australia, shall find out .Cheers, Mark.C.

Mark,

Wasn't trying to beat you up at all. Just passing on what I've experienced with a lot of engines. The older carbs can take a beating if they didn't have the later ethanol resistant gaskets and diaphrams in them but I've not encountered any issues with gas remaining inside two stroke gas R/C engines that have sat for several years. Oil content in the fuel does make a difference in how long they can sit. More oil = longer storage times. Right now I'm surrounded by about 50 of them and none of them exhibit any ill effects of extended storage without flushing. You should not experience any problems at all if leaving gas in the plane's tank for a couple of weeks.

T O Man, No offence taken, thanks for info and time. Enjoy, Mark.C.

Some think it is "overkill" but here's what I do.... I was having problems with carb diaphragms going bad in as little as 4 to 6 weeks. I don't know if it was my fuel source(s) or what, but I had a run of bad luck with carbs, whether I ran them dry or left them full of gas. So, I started using what I call "Storage Fuel". It is Coleman Camp Fuel, with Sta-Bil added, and 20 to 1 oil mixed in. After I am done flying for the day, I drain my regular fuel out of the plane, fill the tank about half full of the "Storage Fuel", and run the engine long enough at various throttle settings to be sure the fuel has gotten all through the carb and engine. Then I choke the engine to kill it, and store the plane. No carb problems since....

AV8TOR