Topic: E85 -- Downside

[robert]

The downside is vapor lock. It seems to occur when the vehicle has 1/4 tank or less, and has been at rest for between 30 minutes to an hour.

Very bad news.

Whatever you might read about it not happening is not true--it happens.

I got my vehicle started by shaking it repeatedly while in park. I understand starting fluid squirted in the air intake will work. It's a bad problem. My guess is that the alcohol has a high evaporation rate, and can lock your system with vapor. Keep your tank half full or better--carry starting fluid--but beware!

[TinkerFreak]

I'd go with a fuel filter, first. I also had to change my fuel filter sock a little while after sitting for 18 months. My car started right up after sitting that long, though. If you're in a cold environment, then you're going to see some of that behavior. Plug heat range and AFR can also be the reason for a popping + stuttering.

Don't give up hope. Just realize that this is part of playing with something new. You have to be able to work through new problems that were your own doing. I had to learn that, too. It's also usually something simple. Might you be on a higher ethanol blend that starts harder since it's a few months old?

[paganegyptian]

I just tried cranking the Firebird after a month of sitting... It pops, shakes, then backfires.  the E85 in it is probably 1.5-2 months old. I purged a little of the fuel, and its kinda yellow, I bet its went bad. I have never stored E85 that long... I wonder if I should drain it and fill it with fresh. Isn't storage for E85 only about 30 days if I remember right? I know gasoline is only 45 days when it varnishes.. maybe the gas varnished in it...

[1outlaw]

It is not vapor related then if it is cold now AND you are running E10. E10 will have a higher vapor pressure than E85 especially if the gasoline base of the E10 is conventional NL instead of CBOB or RBOB. Very strange indeed. Dumb question for you engine/controls guys-- does the sending unit (fuel level indicator) have ANY effect in fuels of varying continuity if it is going bad? Can it short out to the liquid? What else would move when he shakes the truck?

Does the engine cut out or stumble on accel/decel/curves/bumps?

Is the fuel gauge always accurate?

[robert]

It's a weird alright. It's not heat related. It's December now, and cold. In fact, cold weather might exacerbate the problem. But, here it is again, if I fill up on E85 (and it's not that great a deal nowadays), whenever my gas gauge hits 1/4 tank I have starting problems. Like - it won't start. It rather acts like it's a vapor lock, but I don't think that's it. Interestingly, a cure is for me to go to the back of my truck and shake the hell out of it. Mix up the odors, I guess. Usually, this allows the vehicle to fire up so I can get gas in it.

If I run a full tank of gasoline (E10), I don't have these symptoms. In fact, I don't have them if I run 50% E85  & 50% E10.

[paganegyptian]

I also have a 2000 S-10 FFV truck, and this is a little disturbing to hear.  I have 180,000 miles on mine, and have never had that happen.And I always use E85 also.

I have heard of this even in Gasoline vehicles. Did you open your gas cap to vent pressure? One thing I noticed on vehicles that do that, is when the exhaust is very close to the fuel tank, it literally boils the fuel in the tank.  Do you know of any exhaust changes on the vehicle?  This is typical when makers like Ford, especially the Police Interceptor Crown Victorias run both exhaust pipes right against the fuel tank. I have had a huge vaccum in the tank because of it, be extremely careful when opening the cap.  Being a former Police Dept. mechanic, this is the second dumbest design in a gas vehicle I have ever seen.

If it happens again , try that and let your fuel cool down. It may be a good idea to look underneath the truck and see how the exhaust is ran, it may be worth while to change the location of it slightly or put a heat shield around it by the tank.

Keep us posted on this.

[1outlaw]

Robert- i have an identical 2001 S10 2.2L FFV. I always run E85 in it and have for over the 2 years I have owned it. Mine has the original drive train and only has about 60,000 miles. Mine has never vapor locked and I run E85 made with natural gasoline for the 15% gasoline component. Natural gasoline can be even more volatile than gas -potentially having a boiling point in some areas of the country as low as 100 degrees F----this is why i asked you what color your E85 was in a clean glass jar.

Good luck finding the cause on this Robert- If you can find this I think you will really like E85 in your truck. It has given me noticible improvement in auto shift reduction in cruise control and will run with better efficiency by far in terms of btu/mile on alcohol vs gas than a lot of the other FFVs can reach.

[robert]

I'm gonna take your advice Corey. Maybe I'm lucky and E85 is providing me with an early warning system of future problems. That type problem seldom hits conveniently, either. I'll take no chances and just replace the fuel pump.

[Corey872]

Sounds like you may have a plugged pick-up filter on the fuel pump.  There is a picture of the set-up here;

http://www.car-stuff.com/mmparts/chevy-s10_pickup/fuel_pump.html

The pick-up filter is the white rectangle piece.  If this gets plugged or starts to deteriorate with age it can choke off the inlet flow to the pump.  When you have a full tank of fuel, there would be enough pressure from the fuel level to force fuel through a partially plugged pick-up filter.  But as the level drops and/or the fuel heats up, you probably hit a point where the pump can't pull fuel through the partially plugged filter.  This is really the only place you can get 'vapor lock' in a modern fuel system...everything else is under pressure.   It's really more of a pump cavitation than vapor lock, but the results are the same.  The solution, of course, is to clean and/or replace this filter.  If you intend to keep the vehicle, you might consider a new pump as well - with 130K on the old one.

But with the system in proper working order, there shouldn't be any pick-up issue.  I have routinely put 13-13.2 gallons in my 13 gallon tank - even on 100F degree summer day - so there really isn't any issue with the fuel.

[robert]

Thanks for the advice hotrod.

The truck is EFI
It never overheats.
There are no modifications.
The engine has 20,000 miles on it. It was replaced with a new factory engine about 10 months ago. It is E85 rated.
The fuel pump has 130,000 miles on it. I have never checked fuel pressure.
The problem goes away when using regular unleaded gasoline.
I certainly could have a bleed down problem on a 7 year old truck, someplace. If so, E85 exacerbates the problem.

[hotrod]

Not saying it is not a fact, we are saying you have a problem you need to fix as it should not do that!

You still have not answered our basic questions.

Are you EFI or carburetor? (I assume EFI given its age)
Is the system using an electrical fuel pump at the tank or a mechanical fuel pump (I asssum electrical based on its age).

Have you replaced the fuel filter?
Does the truck ever over heat?
Have you made any modifications?
Have you looked at the fuel lines to see if they are resting someplace they should not be?
Have you checked your fuel pressure when the engine is running?
Have you checked your fuel pressure after the engine is shut off?

Many newer cars hold (or should hold) about 43 psi fuel pressure in an EFI fuel system for hours or days after you shut it off.
With pressure in the lines, vapor lock is not possible. If yours should do that, and it is not, you likely have a bad fuel pump, a bad fuel regulator, or a leaky fuel injector or some other problem that bleeds down fuel systerm pressure when it is hot which is making is prone to hot start vapor lock.


Next time you have a no start when it is hot try this trick --- turn the key to the on position for about 10 seconds before you twist it that last bit to crank the engine. That will give the fuel pump time to pressurize the fuel system before you try to start it, and may completely eliminate the problem.

Larry

[robert]

I am driving a 4 cylinder 2001 Chevy S10 pickup. I put a lot of miles on it. I am telling you that when using E85, if your tank gets to about 1/4 full, you stand a danger of vapor lock. This apparently occurs when the engine is at rest for 30 minutes to an hour at outside temperatures of 85? Farenheit or above. Stop and go driving -- ie, a quick trip for a Coke, etc. -- no problems. Park at your house overnight -- no problems. Turn the engine off for 30 minutes to an hour with E85 and about a quarter tank of fuel -- at least in a Chevy S10 flex fuel engine -- vapor lock is a real possibility with E85. I am here to tell you this is no rumour, it is a fact.

[hotrod]

Tell us a bit more about your car/engine and setup, and we can give you better suggestions, including what fuel blend you are using.

Dry ethanol boils at 78.3 deg C (172.9 deg F) so something is getting your fuel very hot. Some gasolines boil at even lower temps so if you are running a fuel blend it might be the gasoline not the E85 that is causing the vapor lock issues.

Buy yourself a spray bottle like is used to spray window cleaner or other cleaning products and fill it with plain old water. The next time it happens spray water on the fuel pump if it is on the engine and on the fuel lines where they are near hot areas like engine exhaust, radiator hoses or heater hoses. You will likely find a location that as soon as you cool it off with the water spray the engine will start normally. Once you find the problem area that is where you need to make changes to keep the fuel cool. The problem of vapor lock is not unique to E85 gasoline will do it too, especially in the early spring summer when you might have a high volatillity fuel blend still in the tank from winter driving.

It is a heat management problem with your engine and fuel system and it will go away as soon as you locate the point where the heat is boiling the fuel. If you have a fuel pump on the engine the quickest and most reliable way to solve the problem is to go to an electric fuel pump located close to the fuel tank so it pushes the fuel to the engine rather than sucking it from the tank.

Also check your fuel filter and make sure it is clean (probably a good idea just to change it out for a new one to be sure.)

Larry

[1outlaw]

Are you carburated robert?

We found this in some aircraft testing in gravity carb applications- if you have a low pressure system and you are getting vapor lock- insulate your fuel lines or move them away from exhaust manifolds or other hot surfaces. What we think we found was the gasoline portion has the potential to boil (initial boiling point) at 60-90 degrees before the alcohol. For  us it occurred at full power and full heat.

Is your E85 absolutely clear or does it have a yellow tinge?

If you are fuel injected- is this a Ford Taurus??

Are you at 85% alcohol or do you have a different blend in it such as Spring or Winter (or added gasoline)?

Since this is after you shut it off- the heat is climbing under the hood once airflow stops- can you find the problem area?