[jrbartlett]

You better check that gasoline again. If San Antonio is an ozone non-attainment area, as Houston is, the stations are required to sell oxygenated gasoline -- which means it does have ethanol in it, whether or not it is premium. Maybe San Antonio is in compliance with ozone standards, in which case you might have a choice.

[Tom400CFI]

I'm sorry, but I agree w/the folks who "called names". No WAY you're going to boil gas in a modern, PFI engine. Even if you had a situation where your fuel rail temp was high enough to boil gas (like during a MAJOR over heating event), as one poster said, the gas is recycled back to the tank at a high rate; the pump pumps WAY more than the engine can use. So at the rate that the pump pumps the fuel through the fuel rails, and back to tank, you'd have to see tank temps nearly as high as the boiling point of gasoline...at 45+ PSI. Anyone see or touched a gas tank near empty after the car has been running on a HOT day? It's MAYBE 110*F. THAT is what is being pumped to and through your fuel rails, and back to tank. I don't see how it could possibly boil.

To answer the poll, No and no. I've never had boiling gasoline in any car, boat, snowmobile, bike or anything, 1910 to now. I don't know who the mechanic in question is, but I am a mechanic and manage maintenance on a fleet of over 100 pieces of equipment. I could be wrong...but so could he. Science, as I know it, says that he is the one who is wrong.

[simplyconnected]

Reatta Man, nobody called you names. We are all car guys with extensive background experience and education, not showmen or braggers.

You mentioned the boiling point of ethanol. Ok, at what pressure? Here's a quote from YOUR resource:
"... That said, the reason why a fuel injected car shouldn't vapor lock is because the fuel should be under enough pressure that the pressure itself stops it from vaporizing in the lines, sort of like how your pressurized coolant system prevents the coolant from boiling."

Do you have thousands of cars in Texas, disabled by the side of the road from vapor lock? They all suffer the same heat and use the same fuel. How come all the Flex cars using E-85 still run ok? No, you have isolated instances.

By the way, vapor lock IS boiling; the temperature AND pressure at which a liquid turns into a gas. The physical science of vapor lock is easily proved regardless of what anyone feels about it. There's no mystery and nobody is in denial here, so don't take it so personal.

Carbureted cars with fuel under suction are prone to vapor lock, not EFI systems.
- Dave

[joe_padavano]

Originally Posted by Reatta Man

One other thing--other car forums agree that it CAN happen, and manage to talk about it without calling anyone names.

Well, since everything on the internet must be true, here's another quote from Wikipedia:

Originally Posted by Wikipedia

Vapor lock (also known as vapour lock) is a problem that mostly affects gasoline-fueled nternal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump...

So I'll say it again. Since the electric fuel pump is in the tank, vapor lock is NOT the problem. Engine-mounted mechanical fuel pumps are subject to vapor lock. The vapor causes the mechanical pump to lose prime. Electric pumps in the tank are covered by fuel and do not heat up and vapor lock. Remote electric fuel pumps on carbuerated cars do not vapor lock either.

Also, since the EFI system has a recirculation system with a pressure regulator in the return side, any pressure above the set point of the regulator causes fuel to be returned to the tank, even if the system is not running. Also, the EFI system turns the pump on for two seconds when the key is first turned to the START position to prime the fuel system and purge any vapor in the system.

Once again, until someone can explain to me the exact mechanism that this supposed "vapor lock" causes in a modern EFI system, I remain unconvinced. Vapor lock specifically refers to fuel vapor prevening the pump from drawing fuel. I fail to see how vapor on the pressure side of the system can prevent the pump from drawing fuel. The links you provided did not explain the physics, only symptoms. Many mechanics also claim that putting a plastic-case car battery on a concrete floor will cause it to discharge (but the same battery apparenly won't discharge when on the metal racks in the store or the metal battery tray in your car). They are also wrong.

Many other temperature-related failure modes exist, and I'm willing to bet that the real problem is a sensor going bad with a thermally-related intermittent problem.

[Dave@Moon]

I fail to see how vapor on the pressure side of the system can prevent the pump from drawing fuel.

I can think of one way. If for some reason the fuel return line was plugged, and the fuel pressure valve was unable to do it's job, then the ultimate pressure inside the line might be overcome with enough heat.

At 45 psi ethanol boils at 208.4 degrees F. However that's typically the pressure with the return line working. Assuming the fuel pump is ultimately able to generate 60 psi into a blocked system (a fairly reasonable limit I would think), that b.p. goes to 224.6 degrees F.

For that to occur, it would have to be hot enough in the engine compartment to make coffee (boil water) in a device strapped to the firewall, not to mention the great clouds of steam generated by driving in the rain. Joe_P is absolutely correct. In practical terms it is simply impossible.

Boiling Point Calculator
Methanol Properties

[Dave@Moon]

One thing I didn't think of when posting the strong fuel smell in my TR6. The tank of gas that was in the car when this occurred was purchased in VERY rural Kentucky about 1/2 way between Louisville and Cincinnati. The last I knew, outside of 3 counties actually abutting Cincinnati northern Kentucky had no oxygenation requirement for it's gasoline. Here in Cincinnati, where all our gas is E10 (10% ethanol), I've haven't noticed a problem in 3 tanks so far this year.

[joe_padavano]

Originally Posted by Dave@Moon

I can think of one way. If for some reason the fuel return line was plugged, and the fuel pressure valve was unable to do it's job...

In which case, wouldn't the plugged return line or non-functioning regulator be the actual cause of the problem?

[old car fan]

I agree with Ted.He hit it spot on.

[Reatta Man]

James,

San Antonio is an attainment city, but just barely. They have been trying to remain in this EPA category for more than 10 years. If we change categories, we get manditory emmissions testing as part of our state inspection, which drastically raises the price from its' current $14.50 price, and causes several other changes as well.

Several retailers, such as Valero (may still be Diamond Shamrock in some areas) already use ethanol, along with Exxon.

Thanks for the post.

joe

[Jay Wolf]

On the way to The Lebanon TN show was the first time ever my 55 Thunderbird vapor locked in the 5 years I have owned it.