Mercury 60-HP Fuel Use

[Dutchman]

Yesterday I wanted to do a quick winterization of my 2008 Mercury 60-HP Bigfoot on my Montauk 150. I added Stabil to the tank, hooked up the [hose adaptor and turned on the water], and started the engine. As always the 2008 Mercury 60-HP BIGFOOT started within a couple of seconds.

I brought the engine to temperature and disconnected the fuel hose at the portable tank, thinking after a couple of minutes the [ENGINE] would starve for fuel and I could change oil, fog, finish the job, and get boat ready for storage.

The engine finally stopped running 36 minutes after I disconnected the fuel line from the 6-gallon tank under the RPS. Needless to say I was surprised how long it took.

This four-stroke-power-cycle engine is fuel injected, and it sips fuel. I had the engine idling at 900-RPM in forward gear. I knew the engine was efficient, but over a half-hour is a long time to wait to finish the job.

I am still a happy and sad man putting the boat away for the winter.

[alloyboy]

Not a good idea to run a fuel injected model out of gasoline. The electric fuel pump is lubricated and cooled as gasoline flows through it. The pump can become damaged when run dry.

Next time you go to use the motor make sure that you use the primer ball to completely refill the fuel system before you turn the key on. When the key is turned to the on position the pump will run for several seconds. You don't want to run the pump without it being submerged in gasoline in the VST

[flymo]

Yes, it's amazing how little fuel these newer outboards use at idle. We always try to remember to put stabilizer in the tank while the boat is still on the water, so we know it flushes through the system. Interesting to know how long it takes to run out, though.

[jimh]

Considering the very low rate of fuel flow, disconnecting the engine from the fuel tank after just a few minutes of idling probably prevented any of the stabilized fuel from ever reaching the engine. As was demonstrated, there was 36-minutes of fuel available downstream of the fuel tank. The method employed here to get stabilized fuel into the engine was not proper.

As FLYMO notes, use of stabilized fuel must begin prior to winterization. You need to add stabilizer to the fuel and let the engine operate at normal cruising speeds for 30-minutes to be sure you have brought stabilized fuel to the engine. My 225-HP engine at idle only consumes about 0.2-GPH.

As ALLOY' notes, it is not a recommended practice to run fuel injected engines without a fuel supply. When you re-start the engine in the spring you will probably have a lot of air in the fuel system which will need to be purged. Typically this occurs as the engine runs, but you may find it will stutter a bit until all the air is out.

[Phil T]

I would re-prime the fuel system, run the engine, and re-fog the cylinders.

[Dutchman]

As FLYMO notes, use of stabilized fuel must begin prior to winterization. You need to add stabilizer to the fuel and let the engine operate at normal cruising speeds for 30-minutes to be sure you have brought stabilized fuel to the engine. My 225-HP engine at idle only consumes about 0.2-GPH.

As ALLOY' notes, it is not a recommended practice to run fuel injected engines without a fuel supply. When you re-start the engine in the spring you will probably have a lot of air in the fuel system which will need to be purged. Typically this occurs as the engine runs, but you may find it will stutter a bit until all the air is out.

Thanks for everybody's advice.

I always use stabilizer in my fuel therefore prior to what I did so it had stabilized fuel in the system already I just mix it a little heavier for winter. Taking off the fuel filter reservoir and emptying it also causes the fuel to be gone from most of the system. The engine ran a good half hour prior to me disconnecting and it was up to running temp.

Yes I always use primer bulb prior to starting the first time in the spring making sure the filter reservoir mounted next to the engine under the cowl is full (slightly unscrewed to displace the air and fill it with fuel). It takes 10 seconds of cranking instead of the regular 2-3 second to start the engine after which I will let her get up to operating temp and then run her for a while at different speeds including WOT. Making sure everything works. After that first time of the season I don't and never have/had to use my primer bulb, no matter how cold or hot the ambient temp and water were. This engine starts within a couple of seconds and purrs and at idle apparently uses .0306 GPH unlike my Evinrude 2-stroke.
Yes no pump is good to run dry but as with many pumps these are self priming and not running for minutes on end without liquid. As with the previous 5 years I'm sure I'll be enjoying her again in April 2017.

[jimh]

...I always use stabilizer in my fuel...

I don't know that always using a fuel additive to stabilize fuel is necessary. I generally don't do that because:

--the stabilizer is expensive, and it adds to the fuel cost;

--the stabilizer is really not necessary if you are going to consume the fuel in a short time;

--I try to practice some fuel management so that I don't have a lot of fuel on the boat when I know I won't be using it for several weeks or more; when I do use the boat I usually always add fuel to the tank; the fresh fuel should rejuvenate any loss in octane that the older fuel in the tank experienced due to sitting around for a week or two.

I do alter those practices as the end of boating season draws near. I begin to use fuel stabilizer once September arrives, because it is impossible to predict when the last-use of the boat will take place. You might be planning for a big trip in October and the weather does not cooperate.

I am always some what confused by the notion that certain engines must be routinely treated with fuel doped with their manufacturer's favorite fuel additive. Imagine if FORD sold their cars and told buyers you ought to add a can of FORD fuel additive at every fill-up at a cost of $15-per-can: consumers would never buy into that sales pitch. But for some reason if an outboard engine maker says their engine will run better if you put a can of their own special fuel additive in the tank with every gasoline purchase, boaters seem to love to follow that advice.