Question on fuel

[viper1216]

Hey everyone,

Buying a new boat and it's a bit bigger than my old one. Old fuel tank was 21 gallons, new one is 70. Engine is a 2001 5.0 Mercruiser. In the past, I have always only put a few gallons of fuel from the local gas station to get it running from the winter and do all my checks, then I would drop in the water at the local ramp and bring to my slip for the season. Once there, I would top off with fuel from my Marina and only get gas there for the season. With the new boat, it's going to cost quite a bit more to fill so I am wondering if I should stop off at my local gas station on the way to the boat ramp and fill it up there and prob save about a $1 per gallon. My only concern is the Ethanol at the car pumps. (I think it's 10%). Would I be better off just waiting and paying the higher price at the Marina?
Thanks!!

 

[todhunter]

Shop around - you may be able to find a gas station that carries 100% gasoline. It's more expensive than E10, but less expensive than filling up at a marina.

 

[JASinIL2006]

Any idea what the previous owner ran in it? It might already have gas with ethanol in the tank.

In any case, I'd be surprised if ethanol would hurt a 2001 engine. I run it in my '97 engine exclusively.

 

[Scott06]

It depends on how fast you consume the gas. In my experince if you burn through it I have not had issues from typical pump gas. I run ethanol from the pump in my jetski because I fill it from a 5 gal can and go the marina to fill the boats 37 gallon tank because it is easier and worth the $ for convenince. I put stabil in the gas over the winter and havent seen any issues with either fuel type.

 

[viper1216]

Good idea asking previous owner. I know he had it a slip at a large lake, so I would assume marine fuel. My old boat had a 2010 engine (3.0 mercruiser) but I would run into ethanol issues and have to rebuild the damn carb every year because of it. This new engine looks like it's the same carb setup, which was why I was worried. Not sure how fast this burns fuel, but I always have a tendency to top of the tank (at least I used too) when it got to about half as I have an unhealthy fear of running out of gas in the middle of the bay lol. So if I fill the tank at a station, chances are it's going to be mixing around for a bit. Especially since I really don't know how fast this will go through fuel. My last boat was a 4 cylinder, this ones an 8. So until I get a feel for how she burns, I'm gonna be pretty much topping off all the the time lol.

 

[tpenfield]

I get both automotive pump gas and marina gas . . . no issues.

 

[achris]

2001 engine is designed with ethanol in mind. Running normal pump petrol isn't an issue... Use the cheapest 91 (RON) you can find...

 

[viper1216]

Checked with the current owner. He did use 91 and was Marine grade. Gonna have to hunt that grade down lol. We have 87, 89 and 93 around here. And my Marina only has 89. So may have to go that route and put in some octane boost each time I guess.

 

[JASinIL2006]

Does the 5.0 require 91? My 350 Mag runs fine on 89 and it even runs OK on 87. I gas up at the station on the way to the river with gas with ethanol every time I go out. I'd be pretty surprised if your engine is that picky...

If it were me, I'd fill up with 89 octane on the way to your launch and then just use whatever is available at the marina.

I think your idea about keeping a close eye on fuel burn rates is pretty smart, especially as you're getting used to the new boat.

 

[nola mike]

Chris is confusing Americans again. The RON used in other parts of the world is different than the aki used in the states. His 91 ron is our 86-87 aki. Use regular grade gas, premium/mid-range has ZERO beneficial effects in these engines (if I were concerned, I'd use top tier regular over cheap premium).

 

[Scott06]

Good idea asking previous owner. I know he had it a slip at a large lake, so I would assume marine fuel. My old boat had a 2010 engine (3.0 mercruiser) but I would run into ethanol issues and have to rebuild the damn carb every year because of it. This new engine looks like it's the same carb setup, which was why I was worried. Not sure how fast this burns fuel, but I always have a tendency to top of the tank (at least I used too) when it got to about half as I have an unhealthy fear of running out of gas in the middle of the bay lol. So if I fill the tank at a station, chances are it's going to be mixing around for a bit. Especially since I really don't know how fast this will go through fuel. My last boat was a 4 cylinder, this ones an 8. So until I get a feel for how she burns, I'm gonna be pretty much topping off all the the time lol.

I suspect if you had to do multiple or frequent carb rebuilds there was contamination of the fuel tank that continued to dose problems into the carb or the carb cleanings were not successful in completely cleaning the carb. Im not throwing you any shade, as Ive had plenty of issues rebuilding carbs over the years....
Bottom line as the comments and experince in this thread lay out you should see no issues from ethanol fuel especially if you burn through it pretty well.

As for fuel consumption I think the 5.0 is about 16 gph at WOT. I have a 5.0 Carb in a 21 ft bow rider (37 gal tank) typical lake cruise or skiing session I'll burn 7-12 gallons. You can google there are some online fuel calculators for merc engine that simulate rpm and fuel burn. I suspect you wont need to fill it all the way and lug around an extra 30 gallons of fuel.

 

[nola mike]

And your burn rate is going to be far more dependent on what the engine is pushing vs. the engine itself

 

[achris]

Chris is confusing Americans again.....

Ohhhh, that never gets old...