MerCruiser Possible Ethanol/Water Issue

[Pirate Dave]

2004 MerCruiser 3.0 Liter
S/N 0W008933

Merc I/O Drive
S/N 0W517697

Took the boat out today - first time this season.

The engine started up with difficulty. It tried to turn over, but wouldn't on the first two or three tries. Finally it did start with a little gas, but stalled if I took it back to idle after starting. After warming it up with the throttle at about 1200 RPM for five minutes or so, I return to idle without a problem.

We ran through up the creek and out into the harbor. No issues through the no wake zones at 12-1300 RPM. Once we were clear, I started to open up slowly. As soon as I started giving gas (maybe around 15-1700 RPM), it started to bog down, almost stalling but catching itself seemingly at the last minute. We turned around and headed back up the creek. Even at low speed (10-1300 RPM), she continued to bog down over and over. Made it back to the pier without a stall (though it seemed close).

I spoke with a Tracker Service agent (at Bass Pro), who suggested that it sounded most like a ethanol break down issue was the most likely problem. It was stored over the winter with a little less than 1/4 tank of ethanol included fuel - though I had put stabilizer in the fuel. His recommendation was to pump out the fuel (now a full tank) and replace with clean fuel.

So a couple of questions:

1 - Will dri-fuel work with a full tank, or should the tank be empty?

2 - Should I empty the tank via the fuel fill hose, or should I attempt to remove the fuel line from the tank?

3 - Should I change out the fuel filter or just see if the new fuel works first? On this model the fuel filter is in the fuel pump - not just a screw off filter.

I am not normally a small engine DIYer - but I have some basic skills and I think I could manage some basic stuff.

Thanks.

 

[Fishermark]

Re: MerCruiser Possible Ethanol/Water Issue

Welcome aboard!

If you do not have a fuel water separater, I would suggest installing one.

By all means, change the fuel filter(s).

Before removing all the old fuel, you might try running the engine from an outboard motor six gallon plastic tank with fresh fuel and see what that does.

 

[thumbdoctor]

Re: MerCruiser Possible Ethanol/Water Issue

Welcome aboard!

If you do not have a fuel water separater, I would suggest installing one.

By all means, change the fuel filter(s).

Before removing all the old fuel, you might try running the engine from an outboard motor six gallon plastic tank with fresh fuel and see what that does.

Long term storage of Ethanol blended fuel promotes "Phase Separation" whereas the ethanol absorbs condensation until saturation occurs. Then the water laiden fuel settles at the bottom of the tank and gets into the fuel pick up. Dry Gas or ISO will only defeat the job of the water separator carrying this unstable mixture into the carburetor(s). If the fuel isn't too old, you can add some Sea Foam or Star Brite Star Tron enzyme treatment. Take it easy on the motor when using this reconstituted fuel until you add fresh because the relative octane will be diminished.

 

[Bondo]

Re: MerCruiser Possible Ethanol/Water Issue

3 - Should I change out the fuel filter

Ayuh,... You should have Already done what is normal Spring Maintenance....
Adding a cannister type filter is Always a Good Idea...

Btw,... Dri-Fuel is kinda a waste of money in gasaohol,... Another can of alcohol doesn't amount to much when your starting at 10% Alcohol....

 

[sea wolf]

Re: MerCruiser Possible Ethanol/Water Issue

I don't know. Do u really want to pump out a full tank of gas on the word of some TSA who hasen't even seen your boat? How do u know he's right? I would investigate other causes such as your carb before going thru all the hassles of pumping out a full tank of gas. But, it's your call.

 

[ENSIGN]

Re: MerCruiser Possible Ethanol/Water Issue

Disconnect the fuel line at the tank and pump out a gallon of gas into a clear container. let it settle and look for a separation of gas and water .You can also add some food coloring to make the water highly visible

 

[cedarjunki]

Re: MerCruiser Possible Ethanol/Water Issue

you said you added stabilizer..... was it marine stabil? the blue stuff? or original red stabil? the original stabil isnt formulated for ethenol that im aware of.

 

[Lou C]

Re: MerCruiser Possible Ethanol/Water Issue

IF it has a water/fuel separator already installed you can remove it and pour the contents in to a large glass jar...let it sit for a while and then see if the gas is the same color all the way through or there is a layer of water on the bottom (phase separation). If so then you have to get the tank pumped if not...you have to look for other causes...thats one side benefit of the cannister style fuel filters...it allows you to get a fuel sample easily and evaluate your fuel storage system and then come up with a reasonable plan...just be careful not O spill gas in the bilge...I take my filter off when I winterize and dump it out to check the fuel and then put a new one on...

If you have a persistent problem with water you need to check your gas cap...vent...to make sure water isn't leaking in from when it rains...

We have had E-10 gas for a long time here and there were problems initially (it cleans out junk in the tank and if you had water in there it really causes a big problem ) but if you can keep the water out and run good 10 micron filters it can be lived with...

 

[Pirate Dave]

Re: MerCruiser Possible Ethanol/Water Issue

So the lesson learned here appears to be: Do the <expletive> spring maintenance.

As noted by Bond-o and others - the dri-fuel didn't really do anything. I pumped out the fuel tank, changed the fuel filter, and put in about 5 gal of high octane gas. For good measure, I opened up the carburetor and sprayed some carb cleaner. (I'll admit that a full soaking or rebuild is probably beyond my expertise.) No real change (still started poorly and stalled out at idle). My brilliant wife suggested changing the spark plugs. Just finished and the engine started right up from cold with no issues. Optest in the water scheduled for tomorrow.

I never noticed a lot of water in the fuel as it came out. I poured some into a glass jar - some sediment but it was bright.