How does ethanol effect older vehicles?

I have a '75 ford f100 with a 360cu in engine. I have had a rash of failures of fuel related parts in the last year. fuel lines, carb diaphrams, even my mech fuel pump have failed. could these problems be ethanol related? I realize it is an old truck and these failures could just be coincidental, but it seems odd. should I use ethanol free gas.

Those failures are most likely the result of ethanol. If -non- ethanol fuel is available it would be worthwhile to use it for improved performance and fuel mileage but the new fuel pump and fuel lines are likely compatible with the ethanol.

please excuse my need to correct the post. Thanks again @missileman.

Cars designed and made in the mid 70’s had no provisions in their design to deal with the level of alcohol in modern gas. You can buy and should use an ethanol fuel treatment which is sold in most auto stores with a label on it for marine use. There are lots of old marine motors out there still in use, and in your case an old truck still in use.

All of the issues the OP describes are consistent with damage from alcohol in fuel and are very common in older vehicles.

@RodKnox…did you mean to say non-ethanol fuel? I have never encountered any ethanol fuel that improved performance and fuel mileage.

They have been putting ethanol in gasoline for 20-25 years…The truck is almost 40 years old…Nothing lasts forever, especially rubber diaphragms and hoses…

thanks for the info guys, I thought it had to be the ethanol because the fuel lines were not failing because they were old and cracking, they seemed to be getting soft and dissolving in the places that they were springing leaks. I re built the carb and hope the new parts can handle it. I think I will get ethanol free fuel when possible tho.

Yes, @missileman. Thanks for the correction.

And the ethanol seems to emulsify the old non compatible rubber, @wesw.

Ethanol in gasoline and its corrosive nature can damage fuel components in older vehicles. The rubber components are usually the first components that display the damage.

In 1992, Minnesota mandated the E10 gasoline be the standard motor fuel to be sold in the state. After this legislation passed, those of us with older vehicles/engines started expieriencing problems with the fuel systems. At first, nobody could figure out what was going on. Until some people in the Minnesota Street Rod Association started testing the effects of ethanol on older fuel systems. Once it was determined what the damaging effects the ethanol had on older engines/fuel systems, the MSRA filled a class-action law suit against state. Their arguement was, that you cannot force the general public to purchase a motor fuel that causes damage to their personal property. So either the state had to provide non-ethanol fuel for those older vehicles/engines, or the state would have to pay for the damages incurred from using ethanol fuel in said older vehicles/engines.

The MSRA won the case, and this is why you can purchase non-ethanol fuel in the state of Minnesota.

Here’s the list of gas stations that sell non-oxy fuel in the area.


Yep. That list includes the Marathon station where I buy about 95% of my fuel. Non-oxy premium is the only thing I’ll put in my '65 F-85

When ethanol became common in our area, the station where I was buying gasoline had switched to the ethanol mix. My 1978 Oldsmobile began requiring quite a bit of cranking to start the engine when the engine was hot. My wife suggested that it might be the ethanol, so I went to another station that didn’t have ethanol in the gasoline. My hot starting problems disappeared. In the last years I owned the car, all that was available was the gasoline with 10% ethanol. I think the formulation of the gasoline with the ethanol must have changed because I didn’t have the hot starting problem with the more recent ethanol gasoline.
Small engines sometimes have a problem with the ethanol mix. My 2 stroke rototiller has been very difficult to start. I just filled its tank with a non-ethanol mix that cost $4.80 for a quart. The engine did fire instantly, but then died and didn’t want to restart. I then sprayed GumOut carburetor cleaner directly into the air intake. It then started right up and ran perfectly. I’m not sure whether the non-ethanol gas or the GumOut did the trick. I did all this when I used the tiller this morning. I’ll see if it starts as it should without the GumOut the next time I get the tiller out.

I think if the gasoline used is less than 10% ETOH, the symptoms are probably just due to the age of the truck. I have a 70’s Ford truck and over the years have replaced most of the rubber hoses. The most recent I replaced was from the fuel tank to the charcoal cannister. I sugest the OP to bite the bullet and start replacing any of the rubber hoses that are soft. Easy to do and relatively inexpensive. It’s true that ETOH is a powerful solvent, but 100% gasoline is even more powerful. Gasoline is probably the most powerful solvent anybody would have at their home.

yeah George, I think you are right about completely replacing the old rubber fuel lines. next on my list in fact. I don’t want to go boom.

I have had to replace the fuel lines on my mower, riding mower, snowblower, and string trimmer. They all softened and dissolved. Their ages range fron 20 to 41 years old but all the fuel lines went within one year. I blame the 10% ethanol fuel which is all we can buy. Oh, by the way, I wouldn’t swap my 41 year old Ariens Snowblower for a brand new one.

I have a 20 year old lawn tractor, 10 year old weed eater and chain saw, a 89 Mustang GT, 74 Chevy Nova and a 59 T-Bird…been running that ethanol fuel since it came out in FL a few years ago and no problems at all with any vehicle…There is a place down here that sells 89 octane fuel ( no ethanol ) for 4.25 a gallon ( crazy ). The T-bird just runs on the 93 octane ethanol fuel…had to retard the timing 2 degrees to prevent detonation at WOT…manual states it needs 96 octane as it has the 390 in it and 4BBL which had the heads done for unleaded.