Time Until Issue vs New Fuel Tank

[Captain41]

Now that I have taken ownership of our B31 it is plainly obvious that a new fuel tank is the most pressing need. It is a 1968 hull with the original fiberglass tank and it has never had a drop ethanol in it (according to the previous owner of 20 years). I, on the other hand, live in an area where you can’t find a lick of ethanol free gas. So the question at hand is, after my first use of ethanol-laden gas, how long do I have until I should start to see the effects in the engines.

I know that given enough time it is guaranteed that issues will show up in the engines. Obviously the perfect answer is to switch the tank out right now. That said, it would be great (and I mean great for both owners of the boat if you know what I mean) to use the boat a couple of months prior to taking it out of commission to address the tank. My thought would be to change out the tank in July/August or better yet after this season. What I don’t know is do I have a week, a month, a couple of months or a couple of seasons until I will see issues. I have searched the archives but I found no previous discussion on this timeline issue. I know this is a bit like asking a doctor how long you have to live after a grave diagnosis but your advice will greatly help set my timeline.

I understand no one really knows on an individual basis what I can expect but some sort of ballpark idea from the wealth of experience here on the site would be helpful.

Thanks in advance.

R/Chris H

[Chanse]

On my B26 I put in storage a long time and when recomissioned I wanted to run it and see what I had. I did this
two seasons before putting in the new tank. I live in a area where corn free gas in available at most marinas
however I know of some that cheat! Answer was a test kit. Problem is if your at a fuel dock and you need gas and it
tests bad what do you do. I avoided this by staying close to places I knew and tanking in my own after testing
always testing. What a huge relief to rip out the old tank and getting the new one in and taking care of other issues
that undoubtably you will find. I actually enjoyed the job!
Good Luck have fun

[Captain41]

Chance - thanks for the encouragement. Sorry to say there is no ethanol free gas for anything less than a couple hour trip by water. The tank is the issue now. The question is just when?

[Carl]

We had winter blend here years before we went totally over to 10% year round. I usually only got a few gallons to keep topped off after local Striper trips. Figuring once weather changed or fish left I was pulling boat and didn't want to be calling to make an appointment for fuel. I always felt a difference in starting up and overall performance. Starting cold motors took a series of several short cranking spurts till motor caught. I choked it up to Chokes not calibrated right as it seemed to be a cold weather issue late in the season and early the next...but after a few runs for Stripers and a tank or two of fuel...boat got back to a crank or two to get them started. That said blended non and ethanol I noticed a difference right away.


My first fill up of 10% ethanol into an empty tank was during an early season bass blitz, I was trolling on fumes and ran in to grab a few gallons then run back out to continue...I took on about 30-40 gallons and went from gas dock to 1st buoy outside harbor before Starboard motor started stalling. That about 10 minutes. By the time I was docking the Port began to sputter as well. So within a half hour I went from a boat running like a charm to having two motors stalling like I picked up water in fuel.

Water in fuel was the first thing I checked for...no water was found in fuel/water separators...Did a tune-up...started running again, although hard starting... but it ran...just not great, fuel consumption went thru the roof..then it was valves hanging up followed by bent push rods.

All in all it was very quick to go from no issues to a boat I worried about getting home in.

Carl

[Gert van Leest]

I ran a year on mixed petrol 10 % ethanol...........god what was I happy every time I made it to the next harbour..
The good thing is my sparkplug wrench and I became very close that year...
Go for it , and you will enjoy your boat instead of thinking all the way when it will stop...

[Raybo Marine NY]

Its just not worth it, you will have no peace of mind. If you have to get towed in it will be painfully obvious you made the wrong choice. If you ruin an engine it will hurt even more.

[Jim M.]

I ran mine for at least a year before I had issues, but the issues were expensive. Tearing down the engines, 4 rebuilt heads. I wish I had replaced the tank before the damage was done.

[John F.]

I thought I posted this, but I guess not. When I went through this with my B31 on the Bay a few years ago, I read everything I could and talked to everybody I could. I think Carl gave me some advice at the time. I never ran E10 through my boat. It wasn't worth it to me. Motors are expensive, and you'll have to get a new tank anyway.

[Captain41]

Chance, Carl, Gert, Raybo, Jim and John thanks for the insight and thoughts. So far we have a: just don't do it (obviously the best choice), an hour or 2 until issues and then some got up to a full season (though did cause issues). I'm in the planning phase for a new tank and will start getting quotes next week with the plan to install in June/July. Until then we will most likely only do river cruising on the Severn/Annapolis so I probably won't put much E10 gas in the tank at any particular time. I guess I'm hoping, based on thoughts from the group, that we can use the boat until the June/July timeframe.

John - I know you've been through this locally. I'll be taking you up on your offer to give you a call sometime to go over some of the particulars of getting this done.

Chris

[John F.]

Chris-

Call me whenever. My understanding with the E10 stuff was that there'd be a steady accumulation of stuff on the valve stems and in the combuston chamber, and the valves would eventually start sticking, which may lead to catastrophic failure. Best case with light use was that you'd accumulate the goo, and stop using E10 before things stopped working--but the goo would still be there unless you tore the engine down.

[Craig G]

Here is my plan. Fortunately, here in South Florida, the marinas all have non ethemol fuel. So for now, I don't have to worry about it. When non ethanol fuel becomes hard to come by, my immediate short term solution will be to fill jugs of 100 octane avgas at the nearby Pompano Beach airport. I will then have 2 saddle tanks made that will sit on the deck of my Bahia Mar in front of the engines under the helm seats as an interim fix until I am ready to chop up my nice teak deck for the R&R of a new aluminum tank. At the present time, work and family (life) prevent me from doing any big trips, so jugs of gas or small saddle tanks won't be too impractical as I only fish occasionally, and use the boat mostly for local diving, entertaining and bar hopping. It just isn't worth it to take a chance on ruining two perfectly good engines unless they are worn out anyway and your plan is to re-power at the same time you replace the tank.

[JohnV8r]

Thought #1: You'll never get the voice out of your head that makes you wonder if you're damaging your engines.

Thought #2: A new fuel tank ($5K for fiberglass, less for aluminum) costs a lot less than major engine repairs...OR WORSE, blowing a Series 72 Mercruiser and having to throw away the engines and replace them. That will cost you $35K to replace two gas engines (and the fuel tank) and $70K to convert to diesel.

Thought #3: Once you destroy your confidence that your motors are in good shape, you'll hold your breath every time you head offshore.

Play it safe and get the fuel tank replaced. It is not hard to do yourself if you follow the building tips Capt Patrick has written.