fuel contamination

[Fairbro]

This problem has occured 4 or 5 times in the last season. The boat is left in the water for the season. The cockpit is constantly covered and so are the filler caps. The carbs were rebuilt by a highly regarded shop after it happened the first time. It happens in both warm and cold weather. I get fuel from several sources and mostly marinas. Shortly after starting the 2 Honda 40's one of them quits. It will not restart. I disconnect the fuel line and bleed off a pint or two of liquid that looks like cloudy lemonade. I re-connect the fuel line and restart the motor with lots of choking, killing and short running before it works its way out and runs fine for several trips. Fill caps and vents are tight and waterproof. The cloudy lemonade like liquid turns back to a crystal clear orange gasoline after sitting for awhile. Everything runs great for a few weeks and then strikes again. I always fill both tanks at the same place and time with the same amounts. I have used isopropyl alcohol on two occasions. I know about condensation but this is the first time in 5 years this has happened under identical storage conditions. The one thing that has changed this year is I raise the motors after use now. Any similar cases or solutions?

 

[Sea Wolf]

I'm going to try to suggest to possibilities and ask some questions in blue within your post for clarity.


This problem has occured 4 or 5 times in the last season. The boat is left in the water for the season. The cockpit is constantly covered and so are the filler caps.

The boat, motor gas tank and lines can still heat up and cool down despite being covered. No marine system in a common recreational boat has a sealed fuel system like modern car. Air and moisture can enter your tanks, carburetors, and fuel lines though the tank vents, carburetor jets, and the interior carburetor passages and mix with the gas in the tanks and lines despite the boat cover and anti-siphon valves.


The carbs were rebuilt by a highly regarded shop after it happened the first time. It happens in both warm and cold weather.

There's still temperature changes under the boat cover, rain, shine, or both.

I get fuel from several sources and mostly marinas. Shortly after starting the 2 Honda 40's one of them quits. It will not restart.

Is it always the same engine?

I disconnect the fuel line and bleed off a pint or two of liquid that looks like cloudy lemonade.

Probably has water in it as microscopic droplets.

I re-connect the fuel line and restart the motor with lots of choking, killing and short running before it works its way out and runs fine for several trips.

The interval between these trips is probably short enough to minimize the moisture absorption in between.


Fill caps and vents are tight and waterproof.

See above.

The cloudy lemonade like liquid turns back to a crystal clear orange gasoline after sitting for awhile.

Heat probably drives the water droplets out.

Everything runs great for a few weeks and then strikes again.

Has the interval between these trips been longer or the weather more temperature varied?

I always fill both tanks at the same place and time with the same amounts. I have used isopropyl alcohol on two occasions.

100% isoprophyl alcohol will absorb moisture, help stabilize/stop the gas breakdown, and help water pass it through the system, but your gas mix is probably already 10% ethyl alcohol from the pump, + any other absorbed..

I know about condensation but this is the first time in 5 years this has happened under identical storage conditions.

Has your gas mixture, formula, or alcohol % changed this year?

The one thing that has changed this year is I raise the motors after use now.


This may affect the ability of expanding/contracting air to draw moisture through the carburetors, fuel filters, and lines. Do you have fuel filters on the motors themselves? Are there Racor or other filters in the fuel lines between the tanks and motors? Do you drain and change them regularly?

Any similar cases or solutions?

The expanding/contracting air in your fuel system can bring in the air/water mixture which which allows the water to be absorbed by the hydroscopic (water attracting) alcohol in the mixture.

Then gradually, the alcohol is slowly evaporated in this same daily process, being more volatile than gasoline.

What is left behind is water in your tanks, etc.

The less you use the boat, the less fuel you push through it, the greater this problem becomes.

When you use th boat more, you have less problems.

Boats that set for long periods turn into water carrying gas tankers. And run like old misfiring stinkers.

Use your boat often. Add fuel additives, cleaners, and stabilizers,.

Change and drain your filters often.

If you have a 2 cycle engine with carburetors that can be run dry, disconnect the fuel lines and run out the fuel from the carburetors, then leave the lines disconnected. (Be careful here, some variable ratio oil injected and direct fuel injected 2 cycle and other motors cannot be run dry due to lubrication problems.) Four cycle fully fuel injected engines don't need to be run dry, as they are well sealed. Concult your owner's manual. Someone correct me if I'm wrong anywhere here.

THIS MAY NOT BE ENTIRELY CORRECT OR FULLY EXPLANATORY, BUT IT'S A START, ANYWAY!


Joe.:teeth :thup

 

[C-batical]

Gary,

I experienced the same problem with my C-Dory and also on a Master-Craft that I owned previously. Both boats used the same un-shrouded gas tank vent. Also, the hoses connecting the vents to the tanks in both boats were a straight shot into the tanks. On the Master-Craft I replaced the vent with a shrouded one and connected it to the tank with a hose that I made into an inside loop. There is not much space under the deck to fit an inside looped hose on the C-Dory so I just replaced the vents with shrouded ones. In my case, only the starboard tank contained water and that I attributed to the factory vent being positioned slightly off vertical facing forward. The port vent was facing slightly rearward. I did not notice the water problem, until the fourth year of running. I have not experienced any water in the gas since I did this fix. A photo of the vent I used is in my C-Brat album.

Best regards,
Rollie/C-Batical

 

[Fairbro]

Thanks for the suggestions and efforts to explain this issue. It does seem to always be the Starboard motor. I will try the shrouds, where do you get them and do they replace or just cover the existing vents? I have a drainable Honda filter for each motor and I did drain them before every trip for awhile with good results. Many times I would drain out 4or 5 ounces, check it for clarity ( every time I did this it was good, clear gas) and then dump it back in the tank. I'll say one thing, It has never struck both motors at the same time. It is a comfort to have a backup motor when it takes 10 minutes to a half hour to resolve the problem and get going under full power again. Again, where can I get the shrouds?

 

[C-batical]

Hi Gary,

I also have inline Honda/Racor gas filters installed and did not notice any water in them for 3 1/2 years. I suspect that I was picking up several ounces of water each year and until it reached the bottom of the pick-up tube I did not notice it. When you replace the vents and if your tanks are low on gas you may want to siphon all of the gas out just to make sure that all of the remaining gas/water mixture is removed. If not Bob Austin describes a procedure of polishing the gas to remove the water. Also, I now routinely add a can of dry gas as a preventative measure.

The part I used can be obtained from West Marine or probably from any marina as it is a very common item. West lists the vent as:

PERKO
Thru-Hull Vent
WM Model #: 281360
Manuf. Part #: 0506DP4CHR
$18 .99 USD

Good luck,
Rollie/C-Batical

 

[John S]

I went thru similar problems on my port side. When I finally completely drained the Port fuel tank there was almost 3 gallons of water in the tank.

For some reason C-Dory installed the fuel tank vents on my boat below the rub rail, unlike most others I've seen of my model boat. At a high speed cruise water would shoot straight into the vent and right into the tank.

I also didn't have a loop in my hose.

I finally drilled new holes and moved my vents up higher. I also installed vent hose with a loop in it.

It was too late for my carbs and I kept having problems as small pieces of scale would come loose and plug the carbs and float needles (Yes the Racors will let water thru eventually) After carb overhauls couldn't get every single passage clean I finally ended up replacing the entire intake and all four carbs on the port engine.

For more check out the thread.
http://www.c-brats.com/viewtopic.php?t=6403

Good luck