Sour fuel?

[gayle23]

I have a 1979 6 hp Johnson (model 6R79E) which I have run every week all summer for 10 years with no problems. This spring the engine starts on the first pull, but stalls when I put it into gear and accelerate. I rebuilt the carb. The spark plugs are new. The problem is still there. I checked the water pump to look for obstructions but nothing appeared. I have always added StaBil to the fuel whenever I add fuel to the tank. At the end of the season I leave the fuel in the tank and add new fuel and StaBil in the spring. My theory has been the StaBil keeps the old fuel fresh, and there is dilution from the new fuel, all of which is StaBilized. Has some of this fuel spoiled? How long does StaBilized fuel stay fresh? Thanks.

 

[lindy46]

Re: Sour fuel?

If you haven't replaced the impeller in 10 years, it is time. Does it pump water? Also, have you checked spark? Could be a bad coil. Probably not the gas if it's stabilized. Probably due for a carb cleaning/rebuild kit also.

 

[gayle23]

Re: Sour fuel?

I rebuilt and cleaned the carb, replaced the impeller, and put in new plugs. It is pumping water fine. I will check the spark. It runs fine at low rpm's but cuts out at higher rpm's when in gear. Would a bad coil react that way? Also, I suppose it is possible water has condensed into the gas??? Right now the 6 gallon tank is 1/2 full, all of which is stabilized fuel from last year and, I supose, previous years. Does water drop to the bottom of the tank so it would be picked up by the fuel outlet tube? Thanks.

 

[JB]

Re: Sour fuel?

Sounds like a failing coil. I would just replace both, and the condensors,too.

 

[CaptOchs]

Re: Sour fuel?

I rebuilt and cleaned the carb, replaced the impeller, and put in new plugs. It is pumping water fine. I will check the spark. It runs fine at low rpm's but cuts out at higher rpm's when in gear. Would a bad coil react that way? Also, I suppose it is possible water has condensed into the gas??? Right now the 6 gallon tank is 1/2 full, all of which is stabilized fuel from last year and, I supose, previous years. Does water drop to the bottom of the tank so it would be picked up by the fuel outlet tube? Thanks.

Stabi-fuel does have a shelf-life of a couple of years believe it or not. If you bought a large bottle 5+ years ago it's possible it won't be as effective as a new bottle.

Water does drop to the bottom of the tank. This is more of a problem than recent years with the addition of 10% Ethanol into most gas. A lot of gas stations don't even advertise their gas contains ethanol. The ethanol absorbs water. In severe cases you can get a phase separation and the ethanol/water mix settles to the bottom of the tank. You can try a fresh tank of gas just to be certain.

Another quick test is to pour some gas with your oil mixture into a spray bottle. When it's running at full blast spray a little into the carb. If the engine responds, you could have a fuel delivery problem.

 

[film495]

Re: Sour fuel?

try pumping the bulb to see if it keeps going when you do that. if it does, your fuel pump has seen better days.

 

[gayle23]

Re: Sour fuel?

Thanks. Pressing the fuel primer bulb has no effect at all. I don't think this problem is related to the fuel pump. I think I will replace both ignition coils and replace the fuel. I am inclined to think this problem is related to the ignition coils. The problem occurs only at acceleration which doesn't totally sound like a fuel quality problem. The engine starts on the first pull and runs great at idle. In fact, I have left it run by itself at idle for extensive periods of time at the dock. If I leave the dock and accelerate it will immediately stall.

Thanks.

 

[kenmyfam]

Re: Sour fuel?

I am leaning in the coils direction at this point.

 

[lindy46]

Re: Sour fuel?

Yup - could be firing on one cylinder and idling fine. When you put a load to it, it just dies on the one cylinder.