Fuel Maintenance Strategy

[steveoh]

My last boat was a diesel boat, and as I continue my search for a 325/326 Aft cabin gas boat, something occurred to me. Based on an experience having trouble starting my gas powered hedge trimmers that I left gas in, I started wondering how I should manage fuel in a gas powered boat. On my diesel, it was recommended to keep the tanks full at all times to minimize condensation in the tanks. Also, I suspect it will take us a long time to use the full gas capacity of a 325/326 (162 gallons) and I’m concerned about the fuel “going bad” in that time. By the way, I should probably mention that I live in Southern California because it may make a difference in what blends of fuel are available here. So, here are my questions:

1. Is keeping my tanks as full as possible a good idea to minimize condensation in the fuel tanks in a gas boat?
2. Is fuel stabilizer recommended and how much time will it buy me on the fuel?
3. I’ve heard of Stabil and Seafoam. Is there a recommended fuel additive for these engines?
4. Would buying a higher octane gasoline help with any of this?

Thanks.
Steve

[tomschauer]

If you find a 325/326 you like, I believe at cruise speed with the 5.7s you will burn 20 GPH or more, so it wont take long to burn through the 126 gallons of fuel.
In my opinion...
1. In southern cal, condensation will be minimal, I wouldn't worry about it.
2. I don't use stabilizers, as cleaners and stabilizers are already in the fuel from the refiner. Others swear by it.
3. Again, I dont use any.

4. I always use at least 89 octane fuel.


Again, just me, others will chime in.

[g36]

I agree with above. If you are in So.California won't you boat year round? You will be adding more fuel due to gas vs diesel useage .if you do boat all year you will be adding fuel at different times anyway so I don't think you will have any issue with it just going bad due to age

[steveoh]

Source of the post If you find a 325/326 you like, I believe at cruise speed with the 5.7s you will burn 20 GPH or more, so it wont take long to burn through the 126 gallons of fuel.
In my opinion...
1. In southern cal, condensation will be minimal, I wouldn't worry about it.
2. I don't use stabilizers, as cleaners and stabilizers are already in the fuel from the refiner. Others swear by it.
3. Again, I dont use any.

4. I always use at least 89 octane fuel.


Again, just me, others will chime in.

Thanks for the reply and that's good news about the condensation. Do you use min 89 octane for performance reasons or does higher octane last longer?

We do use our boat year round, but we're not big cruisers. There are some weekends when we won't even take the boat out - it's just an ocean front weekend condo. When we go out, it's often just for a slow ride around the bay - not a cruising speed type of deal where we're burning a lot of fuel. So, I think 162 gallons will last us a while. Unless I hear otherwise, I'm still thinking fuel stabilizer would be a good idea. Thoughts?
Thanks.
Steve

[bud37]

In regards to the fuel questions .......my opinion as always.....the higher octane will give you some protection against knock, but on a computerized boat the computer will handle that with the knock sensor.You will get no performance advantage unless the engines are tuned to run on the higher octane.....the one benefit you will see is it has an increased life as far as degradation is concerned over 87, a little cleaner fuel.

[tomschauer]

Bud, remember the knock sensor retards the timing when sensing detonation, thus reducing power.

[bud37]

Source of the post Bud, remember the knock sensor retards the timing when sensing detonation, thus reducing power.

That it does, worse case scenario.....engine ecu is set up to run on 87, will time the engine on the edge ( timing etc is mapped ) and would only do the knock retard while/if there is a knock present ( very small power band).....therefore you will not see any overall performance gain by using higher octane......

[Viper]

If you're not going to add much fuel throughout the year, use stabilizer. A treatment is typically good for about 6 months. The higher octane won't make any noticeable difference for performance in our applications but it will help to maintain a higher octane level over time. The other thing to consider is that unless you're using non-ethanol fuel, you will draw any moisture that's in the air even if it seems dry down there. How much moisture depends on the amount of humidity. The water separators will catch some of the water but they will reach a saturation point eventually if they aren't replaced before that.

[steveoh]

Source of the post f you're not going to add much fuel throughout the year, use stabilizer. A treatment is typically good for about 6 months. The higher octane won't make any noticeable difference for performance in our applications but it will help to maintain a higher octane level over time. The other thing to consider is that unless you're using non-ethanol fuel, you will draw any moisture that's in the air even if it seems dry down there. How much moisture depends on the amount of humidity. The water separators will catch some of the water but they will reach a saturation point eventually if they aren't replaced before that.

Thanks for the reply/excellent advice. Any recommendation on fuel treatment (e.g. Stabil vs. Seafoam)? I need to research water separators. Is this something a non-mechanic guy can change or is it best left to a pro?

[390Express]

It has always been my understanding that higher octane fuel burns faster and evaporates faster, and will therefore suffer a greater loss of octane if stored over time. You may be starting with a higher octane, but if storing for a longer period of time, I think you'd be better off with a mid-grade fuel.

There are two schools of thought when it comes to storage:
1) store it full to reduce condensation; or
2) store it near empty to reduce contaminated fuel

I've always gone with option 2, and it has always worked well for me. You have less fuel to treat, and less of a problem if you do have fuel issues the following year. The fella that I bought my boat off chose option 1, and it totally screwed me. My biggest issue with getting my boat mechanically sound, has been dealing with bad gas issues, and what to do with the 120+ gallons of garbage gas that I pulled out of my boat.