TOPIC: Modern Gasoline on old systems and engines?

Just picked up a 1970 Evinrude Sportsman 155 and was reading through the owners manual (we got all the original documents with the boat! Cool!) and the manual mentioned using leaded gasoline. Hmmm modern unleaded gasoline also has ethanol in the mix. Is this a problem with older engines? What about fuel tanks? I believe the original tank on this boat was fiberglass located up forward in the bow area. I don't think modern fuel and fiberglass is a good mix.

Thoughts, suggestions, ideas?

Thanks

They haven't had leaded fuel in nearly 40 years. You can run a lead substitute additive if you like. Lead raised the octane & helped the valves (primarily the exhaust valve) last longer. You will be OK running 87 octane but I would try to buy non ethanol fuel if possible.

The ethanol deteriorates the rubber components of the fuel system. That would be fill & vent hoses, fuel pump diaphragms & carb floats. I am not sure about a fiberglass tank, I had a '70 Evinrude Explorer and it had an aluminum tank. But that tank was in the port rear corner as the Explorer had no bow to place the tank. So maybe yours it fiberglass? You are correct, fiberglass tanks don't like ethanol.

Besides causing deterioration, ethanol absorbs moisture from the air until it gets saturated with moisture and you get a phase separation leaving an unburnable cocktail in the bottom of the tank.

Non-ethanol unleaded is a must, especially if you leave gas in the tank. Todays modern oil mix takes care of an lube issues that were taken care of by the lead in leaded gas. No need for any other additives, unless you are running a very high compression inboard...

??? No oil mix in an inboard. They are 4 strokes and don't see any oil in the combustion chambers like a 2 stroke does, if running normally. So lead additive, or non-ox fuel are a necessity on any engines 1970 or older. Auto engines from 1971 on had valve seats designed for unleaded fuel, but not sure on inboard engines.

Desert Doc,

IF you cannot find gas without ethanol in your area (just as there is NONE available within 150+ miles of here), I would contact TallTexan of this forum & ask him to explain to you how to get the alcohol OUT of the pump gas.
You should also use the lead substitute in your I/O engine.

yours, satx

Oooops -- I missed that it was an inboard.. My bad.

I believe that Ethanol was first introduced into automotive gasoline sometime in the 80's and was known back then as gasohal. From what I can tell from my research is that automotive hoses and tubing from about the mid 80's on were made to deal with Ethanol as a fuel additive.

I also understand that older aluminium (in carburettors and such) and plastics have issues dealing with ethanol as well as fiberglass. My main concern here is the fuel tank of my boat.

I would appreciate any classic boat owners that have had to deal with this issue to please pass on your findings and wisdom. Safe boating is fun boating and I intend to have a lot of fun with this boat.

THANKS

Desert Doc wrote:

What about fuel tanks? I believe the original tank on this boat was fiberglass located up forward in the bow area. I don't think modern fuel and fiberglass is a good mix.

Thoughts, suggestions, ideas?

Thanks

Well, you are correct here. I would at LEAST have a good fuel filter inline before the motor. Non ETH gas would be best, but who knows what what used before in it. Read on..

"A few years ago there began to be reports of fiberglass tanks failing. Over the last few years the trickle became, if not a flood, a run ning stream. The Boat Owners Association
of the US (BOATUS) commissioned a laboratory to do testing of fiberglass tanks and found out the alcohol can dissolve the resins in the laminate. As we now know, fiberglass
is not impermeable, as had been thought back in the 60's and 70's. When boats began blistering in the 1980’s, the Coast Guard and others began studies to find out what was
going on. To make a long story short, fiberglass reinforced plastic or FRP, is actually a semi-permeable membrane and liquids will penetrate the resins. This is what led to
blistering. Alcohol will penetrate FRP as well and dissolve uncatalyzed resins. That is,resins that were not mixed well with the catalyst and never set up. If alcohol dissolves
these then eventually the damaged will be extensive enough that the laminate will fail.This does not happen overnight. It takes years, and it takes long exposures to alcohol.
Boats typically sit for long periods of time with full fuel tanks, allowing the components of the fuel to do the damage. This has not been seen on automobiles or trucks because
fuel simply does not sit in the tank and system for very long. However, the research shows that the potential exists for tanks to be damaged in a short time span, 6 months to a year, depending on the laminate, the resins used and how well the FRP laminate was made. But almost all of the tanks that have been reported as leaking have been built in the 1980’s or earlier

Here's a thread the good Dr. Frankenmerc did on the Ethanol fuel you should read Desert Doc. (One of the reasons I read all the sections is because you can often find info that pertains to other areas of interest or brands.)

www.fiberglassics.com/glassic-forums/home/mercury-outpost/ethanol-carnage

I run my 1957 35hp Johnson on E-10 and so far no problems. I did rebuild the carb and have modern fuel lines and tank. One precaution I do take is after each time running I disconnect the fuel line and let it run until empty. I have a fuel pump mod on this motor and a 15 gallon Moeller tank.

Upgrade all fuel hoses. The new ones are all ethanol/alcohol resistant. Fuel hoses should be changed every five years anyway. It's cheap insurance. Any gaskets and other rubber components in the fuel system should be replaced with new ones.

If that boat has a fiberglass tank, replace it now with a modern aluminum or plastic tank. I prefer plastic. No corrosion, doesn't react with anything, meets all epa and USCG requirements.

Remember, you can't walk home from a fire on a boat (not normally anyway)

Ike wrote:

Upgrade all fuel hoses. The new ones are all ethanol/alcohol resistant. Fuel hoses should be changed every five years anyway. It's cheap insurance. Any gaskets and other rubber components in the fuel system should be replaced with new ones.

If that boat has a fiberglass tank, replace it now with a modern aluminum or plastic tank. I prefer plastic. No corrosion, doesn't react with anything, meets all epa and USCG requirements.

Remember, you can't walk home from a fire on a boat (not normally anyway)

Damn right!

All hoses have been upgraded and a heavy duty fuel filter is inline before the engine. Will be looking into replacing the tank and in the mean time using a fuel additive to counter the effect os ETOH in the fuel.

Just got her back from a local boat mechanic that specializes in older boats and got a clean bill of health on the boat from stem to stern. Said it was one of the best kept 45 year old boats he'd worked on in a long time. His suggestion on the fuel tank was double up on the fuel filter, use the fuel additive and not to panic about the tank but that it would be a good idea to eventually replace it with something better and not affected by alcohol. In the mean time....enjoy the boat, which I plan to do.

Now all we need is a good El Nino to bring our lakes back up play level here in NorCal.

Saw your boat in the other thread Doc, she looks really nice!