Flushing out old gas.

[Kender]

Just picked up a 17ft Sunbird 170 and the previous owner hasn't put fresh gas in it since end of last summer. It is an internal tank. I am thinking I can disconnect the fuel line and use the primer bulb to siphon out the old gas, also use this time to inspect it to make sure there is no water in it. Then throw a few gallons of straight gas in it to help flush out the last little bits of old gas and drain all that out. Lastly fill it up like I am ready to go out.

That brings me to another question. Since the boat is new to me and the previous owner wasn't sure of the tank size would it be best to add oil and gas a little at a time, say 3-4 gallons at a time until it is full?

Thanks

 

[wrench 3]

Re: Flushing out old gas.

If you live in a cooler climate you should be OK to just add fuel to top up the tank and mix things up.
How old of an engine are you running that doesn't have oil injection? If you do need to run a mix, mix it in a 5 gallon can and then put it into the boat.

 

[81_chapparel194]

Re: Flushing out old gas.

guesstimate the tank size. may can even google your boat year and make and model for specs and find the tank size... or pre mix 5 gallons at a time in a jerry can and pour into boat.

 

[81_chapparel194]

Re: Flushing out old gas.

google revealed 20 gallons

 

[Lager]

Re: Flushing out old gas.

You will probably find that the gas in there is still OK to use. From last Summer till now is not a whole lot of time and most folks that put their boat away last year start up their boat this year using the same gas that was in there with no ill effects. But you might have some carb problems due to the evaporation in the float bowls as the drying fuel leaves some nasty deposits but I doubt the fuel in the tank has degraded much. Degraded fuel smells like varnish and should be drained, but I doubt your does.
In the future, you should use a fuel stabilizer at the end of the season, especially one made for ethanol enriched fuels.
I would probably run the fuel tank as low as you are comfortable with trusting the fuel gauge, then refuel with a fresh mix.
Hope this helps.

 

[Kender]

Re: Flushing out old gas.

^^^ thanks, my google-fu is weak tonight, couldn't find much on the Sunbird. I'm still figuring out what all this thing has. It is supposed to be a 99 Johnson 115hp. The model number plate on the transom bracket has it as a 1978 140hp so I am thinking that the bracket got replaced at some point. I have to wait until tomorrow to run by the storage lot and peek under the motor cowling to find that serial number to confirm the model year. I forgot to ask about the premix/vro while trying to remember all the other important things, missed a few I guess. I don't remember seeing an oil tank but then again I'm not 100% on what I am looking at. I did see a fuel/water separator in the engine well but with the hatches, live wells, and storage bins I can't remember an oil tank. I will try to get a closer look tomorrow at the motor for the vro and an oil tank plus I plan on calling to po to double check on it.

I have already found that some older vro units had issues but that the newer ones (which this motor is supposed to be) are pretty reliable. Hopefully the vro was NOT removed because that would be a pain to mix 20 gallons in a several stages.

 

[Kender]

Re: Flushing out old gas.

You will probably find that the gas in there is still OK to use. From last Summer till now is not a whole lot of time and most folks that put their boat away last year start up their boat this year using the same gas that was in there with no ill effects. But you might have some carb problems due to the evaporation in the float bowls as the drying fuel leaves some nasty deposits but I doubt the fuel in the tank has degraded much. Degraded fuel smells like varnish and should be drained, but I doubt your does.
In the future, you should use a fuel stabilizer at the end of the season, especially one made for ethanol enriched fuels.
I would probably run the fuel tank as low as you are comfortable with trusting the fuel gauge, then refuel with a fresh mix.
Hope this helps.

I fully intend to use some sort of fuel stabilizer at the end of the season.

 

[Kender]

Re: Flushing out old gas.

If you live in a cooler climate you should be OK to just add fuel to top up the tank and mix things up.
How old of an engine are you running that doesn't have oil injection? If you do need to run a mix, mix it in a 5 gallon can and then put it into the boat.

Depends on whether you consider central Florida as cooler climate

 

[UncleWillie]

Re: Flushing out old gas.

Here is the gasoline test I have been pushing....

Collect a sample of the boat gas in a jar.
If it is cloudy, it has water in it.
If it is Clear, Shake the Jar vigorously. A foamy "Head" will form.
Good gas will loose its "Head" in about 5 seconds.
If it takes longer than 10 seconds to De-Head, it is Questionable.

If it is Questionable...
Make up a small batch of fresh 50:1 Gas/Oil mix. "Head" test it so you know how a good sample should react.
Mix your Questionable sample 1:1 with the Fresh mix and see if the "Head" test improves noticeable.

There is no reason to assume the gas is bad just because it has been stored for a year.
Test it!
-------------------
The fuel tank should have its Capacity stamped on the tank near the Fuel Pickup or the Fuel Gauge penetrations.
Have a peek to be sure.

 

[Kender]

Re: Flushing out old gas.

Here is the gasoline test I have been pushing....

Collect a sample of the boat gas in a jar.
If it is cloudy, it has water in it.
If it is Clear, Shake the Jar vigorously. A foamy "Head" will form.
Good gas will loose its "Head" in about 5 seconds.
If it takes longer than 10 seconds to De-Head, it is Questionable.

If it is Questionable...
Make up a small batch of fresh 50:1 Gas/Oil mix. "Head" test it so you know how a good sample should react.
Mix your Questionable sample 1:1 with the Fresh mix and see if the "Head" test improves noticeable.

There is no reason to assume the gas is bad just because it has been stored for a year.
Test it!
-------------------
The fuel tank should have its Capacity stamped on the tank near the Fuel Pickup or the Fuel Gauge penetrations.
Have a peek to be sure.

Thanks, I'll try that.

 

[UncleWillie]

Re: Flushing out old gas.

Thanks, I'll try that.

Please post your results. :joyous:

This question comes up a lot!
It would be nice to have a simple way to check old fuel that doesn't cost more than the fuel itself.

Thanks, Bill.

 

[Kender]

Re: Flushing out old gas.

Haven't had a chance to check the fuel yet but did find out that it is a 1978 johnson 140hp that the PO would pre-mix. I have to research and see when the VRO came out and if I could add that type of setup to the motor so I don't have to pre-mix a 20 gallon tank.

 

[Outsider]

Re: Flushing out old gas.

You're making pre-mix more complicated that it has to be. It's a 20 gal tank, add the fuel you want, then add the appropriate amount of oil, then go to the lake and enjoy yourself ...

 

[tabike offroad]

Re: Flushing out old gas.

Keep in mind also that most boat shops that are getting in old VRO engines are removing the oil pump because there is no way to tell when they fail and if/when they do the motor is shot. The was the story I got at a Tracker boating center when I bought my used boat. At least with premix you know you are always getting oil

 

[Kender]

Just to update. I tried getting some fuel out of the fuel line using the primer bulb (brand new with check valve and hooked up in the proper direction) but all I got was air. I tried shaking the boat on the trailer and I heard no sloshing of fuel so I am thinking that maybe he ran it dry or there is such a small amount of fuel in there that I may be able to just throw in some fuel treatment and fill it up with good gas and I am good to go.

 

[bryanzzz]

For what it's worth, I have a buddy that has a pontoon with a 75 merc oil injection, last time motor ran was probably September/October last year. Boat stays tied up to his dock all summer, anyway pulled the tarp off it last weekend in prep of putting it in for the summer. Hooked up the muffs and turned on the water, boat fired and idled smoothly immediately!!! Gas at least 7 months old, would not have believed it if I had not seen for myself. Mix up some fresh fuel/oil and go boating...fire it up at the house before putting it overboard. Good Luck

 

[Kender]

For what it's worth, I have a buddy that has a pontoon with a 75 merc oil injection, last time motor ran was probably September/October last year. Boat stays tied up to his dock all summer, anyway pulled the tarp off it last weekend in prep of putting it in for the summer. Hooked up the muffs and turned on the water, boat fired and idled smoothly immediately!!! Gas at least 7 months old, would not have believed it if I had not seen for myself. Mix up some fresh fuel/oil and go boating...fire it up at the house before putting it overboard. Good Luck

Thanks. I will have a full ops check on this thing before I trust it to take my kids out on the water. Once I get the major things, bilge pump system-fuel-seats, then I will be checking all the fluids and grease fittings.

 

[Kender]

Ok so after a long day yesterday of working on the boat and trying to contort myself into all kinds of positions to work in the bilge area I was a little tired and was taking the easy way out. This morning with a fresh nights sleep my ocd kicked in and I couldn't just assume the gas hadn't turned into some sludge type of mess. For my peace of mind I pulled the floor plate that covers the tank level sender and pulled the sender. I was able to see a little bit of gas but not much, used a spare primer bulb and got about 20oz of gas into a bottle. Did the shake test and the foam head disappeared in about 5-6 seconds. It doesn't look cloudy and has that wonderful 2-stroke smell we all know. Took me about an hour all together but I know that I am not about to blow a motor or get stuck on the water.