Is 10% ethanol causing engine performance issues?

V

VTSeaRay

Active Member
Feb 19, 2008
1,905
Northern Vermont / SW FL
Boat Info
2007 210 Select w/5.0L 260HP MPI Mercruiser Alpha 1
Engines
8 cyl 5.0 Merc mpi, w/alpha 1 with 19" prop, with the speedo hole on the leading edge just above it
This is the first year I've started with a fresh tank of 10% Ethanol gas. Last night while running WOT for a short bit, I noticed that there were some slight fluctuations in speed that I've never noticed before. (this boat is kept on a trailer and the bottom is very clean. The prop and lower unit are all clean as well. I did notice the lower unit oil level reservoir down a bit, so I'll top that off, but I can't imagine that being the issue. I'll be checking all the other fluids again as well before I go out again to see if there are any changes in any of them. I've been out 2-3 other times this year so far, and hadn't had a chance to do a run on perfectly flat water till last night yet.

No gas station around me has Ethanol free gas anymore that I know of. Should I start mixing Startron with it (or some other additive to take are of the Ethanol side-affects?) Or am I all wet and it's probably something else?

-VtSeaRay
 
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Ethanol has a lower energy content than gasoline so there is a loss of power and/or economy with it's use. That is in addition to the other problems ethanol has with water absorbing tendencies and corrosion.
The additives will help prevent some of the problems ethanol can cause but won't restore the power
 
Yup...Startron suggests a mixture of 1 oz. for every 2-3 gallons. I'd need 2 gallons of Startron for every fill up.
 
Funny thing. . .I noticed the same thing this year.

Engines run smooth -> but maybe once every few minutes, I would see a 200-300 rpm "dip" on the tachs. You could feel it in the boat. Funny part was that it only happened on ONE engine. I attributed it to stale fuel, and seems to have gone away after the first fill of fresh gas. I did put stabilizer in the tanks before the boat was pulled last fall.
 
Ethanol in itself will not cause engine power fluctuation issues but any water that gets absorbed in the fuel will. This usually is a result of fuel that has sat around a while. If you are burning through fuel at a regular pace there should be no issue. Just be sure that end of season the fuel is treated correctly for storage. The later fuel injected engines are designed and tested to withstand alcohol fuel (e.g. 10%). I'm a retired engine engineer and have tested many powertrains.
 
"Yup...Startron suggests a mixture of 1 oz. for every 2-3 gallons. I'd need 2 gallons of Startron for every fill up."

You can buy different concentrations of the Star Tron. I use it with every fill up and use the small bottles which 8 oz treat up to 48 gallons. I don't know how big your tank is but they have one formula that one gallon treats ups to 2,048 gallons. I am guessing your 290 is substantially smaller than that.

The 210 cuddy I have has a 50 gallon tank and one small bottle is plenty to treat it.
 
It was stored last fall with 2/3rds of a tank of gas (40 gal tank) with stabilizer in it. It did act more like a fuel starvation /fluctuation where the RPM's dipped 2-300 RPM's. I did run it way down to the bottom of the tank(1% of fuel left when I got to shore) on my prior outing, so I'm wondering if I sucked up some water that was in the tank. I'll hit it with some Startron when I fill it up this week prior to my next outing and see if that changes things.
 
I agree with statements about likely having some water in there. I also agree that if you burn through the fuel fast enough (also taking into account your location and that it is on the trailer) that you shouldn't have to worry about it. However, a boat fuel tank is more likely to pull in atmospheric moisture than a car's tank (this may change with the new tank laws coming out). That being said, I think it's a good idea to use the Startron all the time - it can't hurt.

I wasn't aware of different formulations of Startron (other than gas/diesel), but the stuff we have at the store treats 16 gallons per ounce (8 gallons for the first time). That's pretty cheap insurance (assurance)! Note that if you put in more Startron than is recommended you won't hurt anything.

It's best either fill your tank for the winter, or completely empty it. I think filling it is the easiest thing, making sure to put in a healthy dose of Startron.
 
I think I experienced this in my 15 yr old Toro push mower this past week too. I was mowing and all of a sudden the rpms dropped off a bit from it's normal maximum for no reason. I pulled the air filter, and cleaned it out, it wasn't that dirty (new last fall), so I'm thinking I might need to hit startron in all my gas powered vehicles. My neighbor's weed whacker gave him grief a couple weeks ago as well and he' thinking it was ethanol issues. A friend of mine's son works in a small engine repair shop, and they have so many fuel system rebuilds since ethanol has hit the market they can't keep up.
 
Thanks for the links. I never knew there was a small engine formulation. I've been using the marine form for my mower, trimmer, etc. Actually, it probably ends up being a triple or quadruple dose! It's been working well, so I'll probably just keep using marine form.

And...
kybishop said:
First time I noticed it was when I saw a big jug for pretty cheap. Turns out it was one that treated less fuel per oz. Tricky that way.
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Yeah, don't you just luv it?!?!
 
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I experienced this last summer. Turns out my EFI was vapor locking. I had a fuel lift assist pump installed and it took care of my problem. Ethanol was part of the problem, being very hot out was the other.
 
Last season I didn't get to use my 28' ProLine walk around much as business was pretty good. It had a 140 gallon tank on it. The last time out I had thought I filled it. When I got home I treated it to a heavy dose of the Starbright. She sat for about a month and a half before me and the Admiral decided to take a day off and head to the coast. She started at home and off to the boat ramp we went. I dumped her off the trailer, parked the truck and jumped on her and had a helluva time starting the big Johnson:grin:. After starting, we proceeded out of the cove toward the channel spitting and sputtering the whole way til she decided to quit in the middle of the channel and strong current. Tossed anchor and began checking. Found fuel/water separator full of water:smt021 Installed new filter, she started and by the time I could get anchor in she died. I repeated this process until I limped her back to ramp. Brought her to the shop and pulled the access plate and the access plate and sending unit to discover 3-4 inches of water in the tank:smt089 I let her sit and settle for a few days and was able to pump out a full 55 gallon and 3/4 of another one with good gas. the rest was water:smt021 I had never had a single issue before this and always ran the tank empty before bringing her home.

I HATE ETHANOL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
I trailer my boat and could buy gas anywhere. However I buy fuel (almost $1.00 a gallon higher) at the marina because it does not have ethanol and they add a stabilizer to it. You don't realize how much the boat sits or how long it takes you to run through a hundred gallon tank compared to how often you use your car with only a 15 gallon tank.
 
Does the fuel/ water filter help with the ethanol moisture issue? And Startron, Sea Foam, or some other fuel additive stuff help with the rest? And although it may be more expensive a higher grade of fuel could solve the less power problem.
 
patokapirate said:
Does the fuel/ water filter help with the ethanol moisture issue? And Startron, Sea Foam, or some other fuel additive stuff help with the rest? And although it may be more expensive a higher grade of fuel could solve the less power problem.
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If by higher grade of fuel you mean higher octane rating, this will not provide any more power unless your engine is knocking and you have an EFI engine that is retarding the timing. There are no more BTU's per pound of fuel in 91 octane gas over 86 octane gas.
 
Does anybody use Quickare by Mercury? My neighbor has a boat repair shop and recomends it. I started using it a few weeks ago and so far I have had no problems.
 
SeaRide said:
For those of you who trailer, here is a useful website if ethanol free gas is available in your area:

www.pure-gas.org
Click to expand...

Great resource! I've been driving right past two stations that have ethanol free fuel just a mile from where I launch and didn't know it.

Thanks!
 
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