Gas from last summer

[Gacreekz]

I just purchased a 1978 ski supreme with a 351 Cleveland in it. I test drove it and the guy I got it from topped it off with some 93 maybe around 8 gallons. The boat runs perfect till it gets to the bad gas which the first time out was the half of a tank mark. The second day I took it out I ran it till a quarter of a tank with some ethanol treatment In it but still started acting up at half of a tank. I’m going to hook up a water fuel separator to it before I take it out again. I tried running a hose down in the tank but I could not fish it down in to the tank. Will I be able to dilute all the bad gas in the tank?

 

[Scott Danforth]

no.

however you can use the fuel pump connection and pump it out, or you can pull the sender and pump it out.

 

[JASinIL2006]

As soon as you add any gas to the tank, it's mixed in with the old. I don't understand how it would run OK for a half or a quarter of a tank and then act up. Seems as though you'd have problems right away if the gas was bad.

 

[GA_Boater]

Adding new gas to old gas makes more bad gas. New gas doesn't fix bad gas.

Gas from last year doesn't mean it's not still good. However if the old gas has water or other stuff on the bottom of the tank, the gas is pulled from the bottom. You may have other problems, one of which may by a short pickup or hole in the pick up. Look at the tank pickup tube. Also look at the gas in the fuel line when the motor acts up by draining the fuel line into a clear container.

And welcome aboard.

 

[Gacreekz]

As soon as you add any gas to the tank, it's mixed in with the old. I don't understand how it would run OK for a half or a quarter of a tank and then act up. Seems as though you'd have problems right away if the gas was bad.

Yes I would think so too, but it runs like a top until it got to half a tank two days in a row.

 

[Scott Danforth]

you could have a hole in the pickup tube which would start sucking air when it gets low.

 

[Texasmark]

Maybe your fuel pump is having a problem lifting the gas when it's low. Maybe your fuel lines have cracks which allow your fuel pump to suck some air and fuel. At high fuel levels, it's not a problem. As fuel drops, it takes more suction to lift the fuel since less fuel height is helping to push the fuel up the hose and the cracks become an apparent obstacle.

 

[Captain Caveman]

I don't know what part of the country this boat was stored for the winter, but if it was in the north it could still be a fuel issue. 93 octane doesn't mean anything in this discussion. Whether it was 93 octane with ethanol (oxygenated) or 93 octane non-oxy would make the difference. Also whether or not the fuel was stabilized. If he only filled the tank half-way with an E10/oxygenated fuel, and it was stored over a cold northern winter, it sounds like that the fuel absorbed so much water that it reached its saturation point. That would cause phase separation creating a layer of water at the bottom of the tank.

As others said, check your pickup and hoses after draining all of the fuel. It's a cheap solution before you start throwing parts at the problem.

 

[mike_i]

Any idea how old the gas is? Are there any gas filters? It would be a good idea to add a water fuel separator regardless of what the issue is. You said "it runs like a top until it got to half a tank two days in a row". That tells me you have an issue besides bad gas, as others have said maybe sucking air somewhere. Are you able to remove the sending unit to take a look to see if there's crud at the bottom of the tank? Is there a main/reserve fuel shut off switch?

 

[Chris1956]

Some of those older boats had two fuel pickups of different lengths. One was for regular use and the other (longer) was a reserve.

Anyway, it sounds like time to pump out your tank and see if you have water/debris or other stuff. Can you examine the contents of your fuel filters?

 

[Gacreekz]

Some of those older boats had two fuel pickups of different lengths. One was for regular use and the other (longer) was a reserve.

Anyway, it sounds like time to pump out your tank and see if you have water/debris or other stuff. Can you examine the contents of your fuel filters?

I’m going to get the boat out of my shop tomorrow and take a look at the fuel lines. It makes sense that there could be air in the lines because when it’s acting up I’ll put it in gear and give it a little throttle and it sounds like it’s sucking air then cuts off.

 

[Lowlysubaruguy]

Quite often its not the fuel at all that creates it. Even if its the fuel thats that problem. Its how and where the boat is stored and if the tank vents a lot or a little. A boat parked in direct sunlight will vent most of its air when the sun warms it then if it cool cold and moist that night it draws moisture in with the contraction of the air in the tank. Do this 100 times over a winter and you have quite a bit of water. Water sits in the bottom of a fuel tank until its bounced around enough to have pockets Large jello like pockets your probably getting larger concentrations when at lower tank levels. Thats if its not an actual fuel delivery issue.

Here’s what i would do buy 15 feet of 1/4” plastic tubing the semi clear stiff stuff let your boat sit the longer the better work that hose to the very bottom of the tank even if you have to pull a hose or fitting to do so. Kill your battery first no sparks if you ever open a fuel cell. Siphon out a gallon or two and let it sit see if its water or other contaminants. If so Siphon the rest of it out until its flowing clear fuel or the tanks empty.

I live in the northwet and just on the edge of heavy rain cold snowy winters and where the sun light breaks more often. I have done experiments and have come to the conclusion the best way to leave my boats is empty. i tried different variations from full to 5 gallons to bone dry and several times. So my answer is pretty solid. Empty is the best choice. I add just enough fuel in the spring or summer to run it around and then progress up a few gallons at a shot. The lower it is on fuel the better. Any more I just wire up my fuel pump put a hose on the lines and run them dry.

If you can park you boat out of direct sunlight or in a climate controlled environment is best but its not an option for me.

The next issue you battle is water inside a carb is another issue corrosion develops in the bowls the jets and air passages that help deliver fuel are now also a concern. Often times requires being cleaned. My push weed eater seems to be a victim of this every year one tiny little jet is plugged up every year I dealt with it yesterday. I think its because I store it in a shipping container that has huge temp swings meaning more expansion and contraction in the fuel tank and system.