Condensation ... bad gas

Pilar · 09-18-2002, 08:17 AM

Ever wonder about the wet on your car's windows on September mornings?

Any metal or glass surface if chilled below dew point will condense water out of the air.

Even the inside of your boats fuel cell will do this. The water then goes into your fuel and causes poor performance or even engine shutdown. The culprit in the fuel cell is the volume of air in the cell with the fuel. As the tank heats up in the day time the fuel expands and the air expands. This air then escapes out the vent. At night the tank cools, the fuel and air in the tank contracts and air saturated with water vapor is drawn in through the vent. The water vapor in the air condenses on the smooth surfaces on the inside of the tank and runs down into the fuel.

This cycle is repeated daily and the water builds up in the tank.

How do you beat it? Keep the fuel cell as full as possible. Fill it on the way back from the fishing trip. Check your water separating fuel filter often. Before winter storage, treat the fuel with Sta-bil or the equivalent fuel stablilizer.

CAGEY · 09-18-2002, 10:09 AM

Pilar, you hit the nail on the head. I betcha many boaters were not aware of this. I also extend that to my truck which is not used a whole lot after the fishing and hunting season.Complete fill up and stabilizer is a mandatory thing for me at days end. Thanks for posting this. You did a service to a lot of people.

[ 09-18-2002, 11:10 AM: Message edited by: CAGEY ]

Dangerous_Dave · 09-18-2002, 12:02 PM

I agree...fuel stabalizer, keep your tank full and change out your fuel water separator yearly.

H2OK9 · 09-18-2002, 12:40 PM

Pilar-The Mercury Marine service rep for our area recommended to me not to use gas thats been in you tank more than a month and a half because of all the additives! He cited problems with detonation as one reason. He also stated that stabilizer will help...but still stands by his recommendation. I called Mercury Marine Consumer Affairs asking if Mercury has any published data regarding this and was told NO, but that they also stand by this recommendation. I've just recently had a complete power head rebuild on my Mercury 200 EFI and an afraid to run it until I pump out 60 gallons of gas from my tank and replace it with "NEW" gas! Any of you Merc owners heard of this?

Pilar · 09-18-2002, 02:50 PM

h20k9, see your other post.

Many, many running problems on boat engines can be traced to fuel problems. This includes old fuel, damaged/leaking fuel cells, improper premix with 2 stroke oil, poor quality 2 stroke oil, oil pump failure and water in the fuel.

You can get out of the dead car and walk away. Try that 30 miles offshore when your boat ***** out.

[ 09-18-2002, 04:19 PM: Message edited by: Pilar ]

CAGEY · 09-18-2002, 03:05 PM

This could create quite and argument. I agree on one thing. Bad gas is a bad thing. On the other hand dumping 60 gallons of high priced fuel is not a pleasant thought.
My feelings are as long as the engine is running ok on the gas then use it. I suppose it is best and ideal to have fresh gas in your boat all the time but this would be hard to do. If all the fishermen dumped gas at the end of a season oregon would have a real cleanup problem. On one hand i see advice to keep the tank full with stabalizer and then advice on dumping the gas cause it is no good.

If you keep the tank full all the time then i guess we would have to dump it when the fishing season rolled around again as iam sure most of us do not fish or run our boats 365 a year. For some 25 odd years or so i have kept my tanks full with stabalizer. I have had mercs, yamahas,evinrudes and a buick inboard and not once have i experienced gas related problems. Dont get me wrong..i agree with the thought of keeping fresh gas. I just have not figured out how to keep the tank full to prevent condensation and how to keep it empty to avoid having to dump it. :whazzup:

[ 09-18-2002, 04:09 PM: Message edited by: CAGEY ]

Pilar · 09-18-2002, 03:18 PM

Hi Cagey, no argument implied or desired. If you keep the tank full and the fuel stabilized you will not have the spoiled fuel problem. If you believe the stabil literature, 6 months is even ok. I guess I am assuming that most fishers here run their boats pretty often.

We did a survey on that on the board and the most common answer was 50 trips a year. Thats once a week.

Now if you have spoiled fuel, what to do? Call Metro and tell them, there are disposal facilities. Or use it in your car if it has no 2 stroke in it.

Cagey you are right on here, it is a dilemma. It has been my personal experience that a boat that sits alot is a maintenance project waiting to happen. Regular (weekly) use keeps the boat and the fisher happy.

I have a 42 gallon fuel cell. If the boat sits more than 60 days even with fuel stabilizer, I burn the fuel in the truck or little car until it is gone. Then I refill and use fresh sta-bil.

With a new or even repowered motor, the fuel is critical. Detonation or overheat can cause severe engine damage in a new engine. Why? because it is already running hot due to break-in.

Under no circumstances am I advocating 'dumping' fuel in the sewer or street or whatever. Burn it if you can (no 2 stroke) in a car or take it to Metro for disposal.

Pain in the butt you say? Yes it is but so is spending $3000 on a rebuild and frying the motor with crappy fuel.

timinthegorge · 09-18-2002, 04:07 PM

Thanks Pilar........

Keep the big tank full..... and use a stabilizer.

Especially over the winter..... Not that I expect I'll be parking the boat unless the roads are icy......

I do appreciate all the wisdom you're sharing...... and I haven't gone wrong by following the advice of the Mods on this board....

Cudos Pilar!

fishwhenican · 09-18-2002, 05:46 PM

Gas and diesel both have similar "shelf life", 3-6 months. Depends on many factors
such as time in storage from refinery, quality level of fuel to start with, volume of fuel that the station you bought it from pumps etc. Full tanks will greatly reduce condensation, thus water in the tank. With stabilizers added to the fuel it will generally extend "shelf life" to 6-12 months. I have never understood why so many people in the lower 48 refuse to buy Racor fuel filter/water seperators. Fuel quality is generally lower in Alaska, and 95% + people run a high quality filtration system. Diesel or outboard aplications have a clear or blue bowl to allow you to see if there is water in the fuel. You want to see the water before it gets to the engine! There are filters that are supposed to "shut down" when saturated with water, they will, but if the demand is high enough (flow,pressure or vacuum) they will all allow water thru them. Caution with additives, those with alcohol can cause as many problems as they are supposed to solve. Also if they are supposed to suspend water, they will only suspend thier own weight in water. 16 oz bottle with 2 oz of "water absorbtion" means only 2 oz of suspended water. If you are running water separation filters you want the water to drop out in the filter not pass thru as suspended. That said, my specialty is diesel fuel injection systems which I have been doing for 21 years. I don't have much experience with 2 strokes, but I have never seen an engine damaged by poor quality fuel. Damage to the fuel sytem?---MAJOR! engine damage no. Even when someone decides to use jet fuel because it is cheaper, or Arctic fuel in Alaska, which accelerates wear, the injection systems may only last 500 hrs instead of 5000. Gas systems run with more tolerance and much lower pressures (35 psi vs 20,000 psi). Poor quality fuel does not cause wear (low lubricity diesel in a rotary injection pump is diff. because of pressure) only poor running. Doesn't a 2 stroke engine get it's lubrication from the oil? Gasoline basically has no lubrication-- you should see the damage it does in a rotary diesel injection pump.
1. Buy good name brand gas/diesel
2. buy it from a station that pumps a lot
3. It seems as if no major fuel supply company (Texaco, Unocal etc etc) will ever give
a straight answer in regards to a "fuel quality issue". In regards to diesel fuel: the good news is that there is now a SAE standard for fuel lubricity (ness. since 1994 when the max. sulfer content was greatly reduced. sulfer doesn't lubricate--it is the process to remove sulfer that also removes polar nitrogen compounds that do give lubricity to fuel) The bad news is that it still is not incorporated into the ASTM standards for diesel fuel.
4. Use good filters! cheap ones do a cheapo job!
WHOA now my fingers are tired
Mark

Deepslayer · 09-18-2002, 11:08 PM

Remamber you can always get your fuel polished. It's not the cheapest solution, but in my opinion is more freindly to the environment.

09-18-2002, 11:55 PM

It was so wet in Ketchikan that if you left a fuel tank half full it was full in less than a month. :depressed:

Fishplay · 09-19-2002, 12:46 AM

Just one word of caution. As pilar says, one part of the sequence involves fuel expansion. So when you fill your tank dont overfill or top off. If you don't leave room for the fuel to expand it seeps out the filler tube and depending on where that is located you could end up with a mess not to mention a possible safety issue.

boater · 09-19-2002, 06:18 AM

if you fill your boat up on the way back from a fishing trip and then stabilize it and park it you are not getting a fully treated system, you need to run it after you stabilize it to get the stuff into the whole system, if you dont you will end up with junk gas in your carb and fuel/water seperator.

i personaly dont fill the tank up, actualy when it sits its as close to empty as possible with treated fuel, i have a fuel water seperator with a clear bowl and just empty it when i need to, i perfer to only run my boat on fresh gas.

Pilar · 09-19-2002, 07:52 AM

Great point, Boater. 15 minutes running on the garden hose will get the sta-bil run through the whole system. I use Sta-bil all the time so it is already there.

I guess there are people who park their boats for the winter. Personally I can't imagine leaving mine unused for more than a couple of weeks. Running the boat on a regular basis relieves many of the problems we are discussing here.

Fish whenican - I doubt if 'old fuel' causes any damage directly to an engine. It is the ******* up carb, filters and as you say the fuel system that suffers. I have noticed that my old mercruiser runs hotter with old gas and has very poor performance.

The kicker won't even idle with old fuel.

Tell us more about the glass bowl type separators. Where can i get one and is Racor the best brand? I've never seen them in any store I visit. I use the Mercury cartridge type that you can't see through. It would be very good to see the water and then you could decide if watered gas was the reason your boat ran badly. You could also dump the water as these usually have a drain valve.

[ 09-19-2002, 08:55 AM: Message edited by: Pilar ]

boater · 09-19-2002, 10:52 AM

pilar, you can buy a racor replacement filter with a clear bottom that screws onto your housing, boaters world and alot of the marinas up here have them in stock. they have a valve in the bottom and when you see water just drain it out, you still need to change them once a year.

[ 09-19-2002, 11:53 AM: Message edited by: boater ]

fishwhenican · 09-19-2002, 08:10 PM

Pilar, RAcor filters are avail. at Englunds marine, from Oregon Fuel Injection (me)o-f-i.com, or any of the large boat supply stores some boat dlrs carry them. To look at them go to
Parker.com then to filtration,to racor,to marine products. Inboards, because of heat issues,should not be fitted with a clear bowl ( bowl is actually plastic). Filter units are Coast Guard approved. Mark

will_e_fish · 09-19-2002, 11:14 PM

Amen again and thanks for the stabilizer reminder! I was thinking the process over and going through the garage hitting all the other motors and gas cans with Stabil. I really hate it when spring comes around and it is time to start the lawnmower. Arrrrgh.... when the verdict is bad gas or carb service. It seems like bad gas never affects the pressure washer or weed wacker though. Yep, so the outboard gets more attention as usual.
:grin: