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Strange Road Trip problem-- maybe Ethanol?

I just finished a 2000-mile roadtrip in a newish-to-me 1986 Accord. It went just fine except at one point, in western SD the midgrade (88 octane) gas was cheaper than the regular (85) and contained 10% ethanol, so I figured what the heck and filled it up with that.

About 15-20 miles down the road, the car started missing, and then suddenly shut off. After some quick roadside diagnosis (fuel pump running, had spark) the thing started up and ran… for a while. That whole day, it would run for about a half-hour, then die and I’d have to wait 10 minutes or so. By the next morning I was down to a half tank, and was able to drive it into town and fill it up with non-ethanol 85 octane, from which point I had no further problems.

If I had to guess, I’d say it might have been vaporlocking, although I have to admit I thought that was more-or-less impossible in a fuel injected car. But if the ethanol lowers the gas’s evaporation point, perhaps that’s what caused the issue.

Has anyone ever heard of such an issue with such a light ethanol blend? Is this an indication of some component on its way out? I’m especially concerned because my state switches to E10 in the winter and I’m hoping the car will still run on it!

Assuming it is only in the winter, you should have less of a problem with vapor lock if that is it. However I would suggest having the fuel pump pressure checked.

[b]Contrary to what most people believe, vapor lock can occur with a fuel injected engine if there’s any ethanol in the fuel. Seen it many times.

The ethanol in the fuel makes the fuel more volatile. So where vapor wouldn’t normally occur without ethanol in the fuel, it can occur with it.

Vapor lock usually doesn’t occur on short trips. That’s because the hot fuel that’s returned to the gas tank gets a chance to cool down. But on a long trip, the hot fuel that returns to the tank starts to heat up the fuel in the tank. And as the fuel in the tank heats up more and more, it causes the ethanol laden fuel to become more volatile. So when it finally reaches the fuel rail on top of the hot engine, conditions are right for vapor lock.


See, that’s one of the things I like about this site. You can learn something new every day. Thanks, Tester.

There are a number of issues to consider, not just the volatility of the mixture (Phase separation, affinity to water (hygroscopic), aggressiveness etc). Read about it here:

IMHO- you got a bad load of gasoline. It may have had more water than can be tolerated by the ethanol mix.

It could depend on which Accord you have also. The majority of 86 Accords have carburetors and a carbed engine is much more prone to vapor lock than an FI one.

Western SD; pretty hot there lately?
Maybe a combination of the heat, ethanol, and a carb is what did it.

Oops… it’s the FI, 12 valve one.

It was very hot, but it was just as hot the next day.

Thanks for the responses. I guess this also answers my long standing “if the regular costs more than the midgrade, why does anyone buy it” question as well. Do you think this might be a weak fuel pump as well, because if the pump’s not keeping the fuel under as much pressure, its evaporation point would be higher?

I was out there last weekend and its dang near impossible to find premium that is not 10% ethanol. If it was a BP station, that could explain it. I’ve heard of a lot of problems in SD in particular with BP causing the problems you describe. You might want to have the fuel filter changed.

Well, I have experienced what a neighbor friend mechanic called vapor lock in my Nissan Maxima yr 2000 -

for a really long time. Starting after driving awhile is hard ! I have used blended E85 and regular mix for years on this car. Finally, the starter went out from all the hard starting. As a Realtor, I haven’t made much money the past few years, so, have tried to monitor the problem. A small reasonable garage couldn’t find anything at all. However, come to think of it, my motor mount ground was disconnected by a different garage due to some weird noise - which also somehow disabled my heat gauge on the dash. Any ideas ??? The part about a vapor lock condition seems like a viable problem, since my car has had oxygen sensor problems since I bought the car back in 2004, never really had to fix it, since adjusting the fuel mixture with ethanol seemed to have given me plenty of octane, and sometimes the sensor light would go out on its own. Now, I wonder - in Minnesota, we have a legislation to do a mix of regular gas with 20% ethanol by 2012, in all stations, replacing the 10% regulated pumps. There are mix pumps already installed which delivers whatever blend you want to go with in some stations. Vapor Lock is showing up all over the mechanic down the street says. He is convinced it is ethanol related … What say fella’s?

Holy cow, this is from 2007?? What year is it anyway-Oh yeah 2011.

I think you’ve destroyed your fuel system by running too much ethanol. Your engine wasn’t designed for anything more than E-10. Depending on the ratio of E85 to real gas you’re running, you’re probably hovering around E-50 or E-60. I’m not sure why you think increasing the octane will fix your oxygen sensor, but it won’t, nor is it good for the car. Just replace the oxygen sensor.

I do think ethanol is problematic, and do not feel that the legislative mandates that have become a fad for states in corn country are a good thing for the public.

Shadow, I think the way I read it, he had only used E10 "the midgrade (88 octane) gas was cheaper than the regular (85) and contained 10% ethanol" and then filled with NON ethanol 85 octane later on. I doubt he's still needs advice anyway,OP was dated in 2007. Hopefully he has it figured out by now! :)

I was reading suziesez, 2 posts above mine, who posted on May 26:

I have used blended E85 and regular mix for years on this car.

The rest of her post went on to describe similarly-terrible ideas on how to treat a car :wink:

My reason for posting is that the car is running with what seems like in consistent fuel or compression. Runs pretty rough, and the ethanol I have been mixing is to avoid having to use premium on this car at such an expense. I wonder about how much octane premium has ? isn’t it around 98 octane ? ethanol is alcohol blend right ? Fuel additives are essentially alcohol, am I right ? Could it be a fuel pump going slowly or vapor lock - as was mentioned about 5 or 6 responses above mine ?

There have been many debates on this forum about the differences between using a mid grade or regular fuel when the vehicle calls for premium.

The long and short of it is this:

If it “requires” premium, you’re putting the engine at risk by not using it.

If it only “recommends” premium fuel, be aware that the money you save on fuel you will more than likely end up spending on more fuel, because it won’t run as well on the non-premium stuff, and possibly even damage the motor.

There are lots of differing opinions, but I’m pretty sure that about sums it up.

Ethanol is a very course substance, and if the fuel system isn’t designed to handle it, you will wear out the various parts of it, and they will require replacement. Using it as a substitute for premium fuel is a sure recipe for disaster. Maybe not now, but sooner or later. In your case, sounds like now.