Bad gas

[dozer1013]

I want to remove the remaining gas from the fuel tank because I think it's stale

There's not much left in there as far as I can tell but I'd like to remove as much of what is left as possible so I can put fresh gas in without the old stuff mixing with it

What's the best way to go about doing that?

Siphoning? I have a little Wally World hand siphon that works pretty well but keeping the hose in the right spot may prove difficult

Would disconnecting the fuel line and using the primer bulb to pump it out be a better option? Or an option at all?

Removing the tank itself is not an option in this case as that would be a whole lot of effort not worth the trouble

The other option I was thinking was just to add several gallons of fresh gas which would dilute the old stale stuff. Problem is I can't really tell how much old is left and I would think that would work only if there's very little old remaining

Anyway, happy to hear suggestions!

Thanks!

 

[agallant80]

Re: Bad gas

I think its impossible to get all of it out. With that said I think syphoning out what you can with a hose would work. I would get a long hose, secure it in to place and make sure that it is lower than the tank when you do it. How old is the gas thats in there? How much if you had to guess is in the tank and what is the capacity of the tank?

 

[dozer1013]

Re: Bad gas

I think its impossible to get all of it out. With that said I think syphoning out what you can with a hose would work. I would get a long hose, secure it in to place and make sure that it is lower than the tank when you do it. How old is the gas thats in there? How much if you had to guess is in the tank and what is the capacity of the tank?

I bought the boat in June and it had some gas in it, how old that was I have no idea. I've added a few gallons since then to that so what's in there is a mixture of that old gas and what I put in it. If I had to guess I'd say there's a gallon or less left in it now

As far as the tank capacity not really sure but if I had to guess again I'd say in the 20 gallon range

 

[Georgesalmon]

Re: Bad gas

Since every fuel draw fitting I've ever seen is on the aft end of the tank, raise the bow as far as you can. I use blocking and a car jack to get the bow higher than the trailer jack does. I disconnect the fuel fitting at the motor, remove the fitting and put a splicer in the end of the hose. Add another hose long enough to reach the floor, stick it in a gas can and pump the bulb until you get gas flowing, after that it will syphon (slowly) until nearly all the gas is out of the tank. I do this every fall and I did try a syphon hose but didn't work as well. I just burn up the old gas 50/50 with new gas in my old John Deere 425.

 

[dozer1013]

Re: Bad gas

Since every fuel draw fitting I've ever seen is on the aft end of the tank, raise the bow as far as you can. I use blocking and a car jack to get the bow higher than the trailer jack does. I disconnect the fuel fitting at the motor, remove the fitting and put a splicer in the end of the hose. Add another hose long enough to reach the floor, stick it in a gas can and pump the bulb until you get gas flowing, after that it will syphon (slowly) until nearly all the gas is out of the tank. I do this every fall and I did try a syphon hose but didn't work as well. I just burn up the old gas 50/50 with new gas in my old John Deere 425.

I have a water separator filter between the tank and the engine, would the siphoning work through the filter or should I disconnect before the filter?

 

[Georgesalmon]

Re: Bad gas

Yeah, it works, I go through my filter and then replace it.

 

[dozer1013]

Re: Bad gas

Yeah, it works, I go through my filter and then replace it.

Great, that sounds like the way to go. Thanks!

 

[WIMUSKY]

Re: Bad gas

I bought the boat in June and it had some gas in it, how old that was I have no idea. I've added a few gallons since then to that so what's in there is a mixture of that old gas and what I put in it. If I had to guess I'd say there's a gallon or less left in it now

As far as the tank capacity not really sure but if I had to guess again I'd say in the 20 gallon range

It sounds like you ran the boat after you had mixed a few gals of fresh with the old and now you're down to a gal in a 20 gal tank? Heck, I wouldn't worry about getting that gal out. Fill n'er up and go......

 

[agallant80]

Re: Bad gas

It sounds like you ran the boat after you had mixed a few gals of fresh with the old and now you're down to a gal in a 20 gal tank? Heck, I wouldn't worry about getting that gal out. Fill n'er up and go......

+1 if its only a gal of so in a 20 gallon tank than I would not worry about it. That is only 5% old gas in there if you fill her up. I would put 93 in though.

 

[dozer1013]

Re: Bad gas

+1 if its only a gal of so in a 20 gallon tank than I would not worry about it. That is only 5% old gas in there if you fill her up. I would put 93 in though.

well the most I'd put in would be about 10 gals...just too expensive to fill up and I don't use it enough to justify filling anyway

Why 93?

 

[Home Cookin']

Re: Bad gas

Good advice by george there. I'll add a trick: extend the fuel line and run it out the plug hole to get it lower than the tank and let it run.

adding 19 fresh to 1 old is a good option unless the old gas has already broken down (phase seperation) or there is water/gunk in there; look closely at what first comes out.

I'd bypass the seperator. Makes a faster flow, and then you don't need to replace it if you are concerned about the fuel going through it.

Treat the gas when you fill the tank. 93 is not necessary. If you can afford to have your carbs redone in the spring, you can better afford filling the tank ($30 more) and treating the fuel. A full tank does not degrade as much as a partial tank.

 

[agallant80]

Re: Bad gas

well the most I'd put in would be about 10 gals...just too expensive to fill up and I don't use it enough to justify filling anyway

Why 93?

There is a school of thought that fuel looses octane over time. It may be an old wives tale but who knows. For the extra $3 it would cost to fill up between 89 and 93 I would spend the extra money. Or just find an ethnoal free pump. I think all of the ethonal free is 90.

Ethanol-free gas stations in the U.S. and Canada

 

[WIMUSKY]

Re: Bad gas

There is a school of thought that fuel looses octane over time. It may be an old wives tale but who knows. For the extra $3 it would cost to fill up between 89 and 93 I would spend the extra money. Or just find an ethnoal free pump. I think all of the ethonal free is 90.

Ethanol-free gas stations in the U.S. and Canada

That's been my understanding too. I use 91, it's the highest octane in the area and is ethanol free.

 

[Home Cookin']

Re: Bad gas

the advantage is in the ethanol-free, not the octane IMO.

 

[crabby captain john]

Re: Bad gas

Fill it with ethanol free then keep topping it off to eliminate as much condensation as possible and always have a reserve for safety. I have a 90 gallon tank-- always fill when 25 - 30 gallons is used and add Stabil even though I only use ethanol free.

 

[OllieC]

Re: Bad gas

Wouldn't hurt to drop some isopropyl in there as well

 

[dingbat]

Re: Bad gas

There is a school of thought that fuel looses octane over time. It may be an old wives tale but who knows.

You are correct about the octane lowering over time. What most people don't know is that octane has nothing to do with the "quality" of the fuel. Octane is a combustion inhibitor. It is used to raise a fuel's combustion temperature making it less flammable.

High compression motors need the higher octane because of the increased combustion chamber temperature. Otherwise the fuel will ignite prematurely throwing the combustion cycle out of timing. On the other hand, using high octane fuel in a low compression motor (all 2 strokes and most 4 stokes motors)causes the fuel to prematurely ignite robbing power and throwing unburnt fuel out the exhaust ports.

Bottom line, unless your fuel is trashed, there is absolutely no value in putting a higher octane fuel in your tank. Its detrimental to performance if nothing else.

 

[agallant80]

Re: Bad gas

You are correct about the octane lowering over time. What most people don't know is that octane has nothing to do with the "quality" of the fuel. Octane is a combustion inhibitor. It actually raises a fuel's combustion temperature making it less flammable.

High compression motors need the higher octane because of the increased combustion chamber temperature. Otherwise the fuel will combust prematurely throwing the combustion cycle out of timing. On the other hand, using high octane fuel in a low compression motor (all 2 strokes and most 4 stokes motors)causes the fuel to ignite in the combustion process robbing power and throwing unburnt fuel out the exhaust ports.

Bottom line, unless your fuel is trashed, there is absolutely no value in putting a higher octane fuel in your tank. Its detrimental to performance if nothing else.

Would that explain why my BMW gets worse MPG with 89 and better with 93 where as my Chrysler seams to get worse MPG with 93 and better with 89?

 

[agallant80]

Re: Bad gas

You are correct about the octane lowering over time. What most people don't know is that octane has nothing to do with the "quality" of the fuel. Octane is a combustion inhibitor. It actually raises a fuel's combustion temperature making it less flammable.

High compression motors need the higher octane because of the increased combustion chamber temperature. Otherwise the fuel will combust prematurely throwing the combustion cycle out of timing. On the other hand, using high octane fuel in a low compression motor (all 2 strokes and most 4 stokes motors)causes the fuel to ignite in the combustion process robbing power and throwing unburnt fuel out the exhaust ports.

Bottom line, unless your fuel is trashed, there is absolutely no value in putting a higher octane fuel in your tank. Its detrimental to performance if nothing else.

Would that explain why my BMW gets worse MPG with 89 and better with 93 where as my Chrysler seams to get worse MPG with 93 and better with 89?

 

[Grub54891]

Re: Bad gas

I prefer to keep the tank full,even if ya don't use it much,the one time ya decide to go further,you don't have enough fuel. Last fill up of the season gets treated for storage. The added cost of filling up once isn't that bad.