Old Fuel Not Worth the Risk

QuestionI have a 1976 Sea Ray SRV 200 20-foot I/O runabout that I’ve completely restored, including a new (remanufactured) Ford 351 (5.8) V-8 engine. It has not been on the water for the past three years. I’m concerned about the possibility of water and/or phase separation of about 23 gallons of E-10 gas I left in the boat since our last outing.

How can I test for a problem with the gas?

Of course, I could simply remove the gas and replace it with non-ethanol gas. At today’s gas prices, that wouldn’t be terribly costly. However, I would just as soon see if the gas has a problem, first.

Do you have advice about how to test and determine if my gas has collected water or phase separated?

Don Sherwood, Boulder, Colo.

AnswerLet’s look at your main question: Will the gas be a problem? If it started life as 89 octane, it’s now about 50 octane or less — nothing I’d want to run any engine on, much less under load. Where we live, regular (10 percent ethanol) gas is $2.39/gallon. If you can dispose of the fuel you pump out, it would cost $54.97 to replace it. You could remove that decimal and look at the resulting number as what it would cost to replace your Blue Oval if you ran it on that 3-year-old fuel.

Most boat dealers, and probably BoatUS, have test kits for ethanol-laced fuel. You’ll have to make an assumption that it really was 10 percent when you put it in the boat. Any percentage reading you get above that will be deleterious to your engine. As ethanol is added at the fuel distribution point, it wouldn’t hurt to test the fresh fuel you put in the boat each time you fill up.

Separation will have taken place in just the first couple of months, if the fuel had been stored untreated. Some stabilizers will retard the process, but there’s no “silver bullet.”

I hope you have a water-separator filter between the tank and the engine. Any boat with an internal tank should have such a filter. After an extended layup, even after you’ve been able to pump out most of the old fuel, there will be water at the bottom of the tank. Check the filter initially every 10 running minutes. If you have spare canisters you can swap-check-and-dry, that would be an easy way to verify you’re getting the water out.

PS: If you have a mechanic work on the boat, be sure to tell him there may be water in the fuel. I can attest to your style of boat being a son-of-a-gun to paddle!

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