Vapor Lock???

[Harold R]

I had a problem with my Ford yesterday that has me puzzled........wondering if some of you may have some insight and opinions with this.
I have a '94 Ford Tempo work car with a 3.0 v6. I drove it yesterday about 200 miles, then pulled off the highway into a burger drive through. I had the car idling for about 20 minutes, when it sputtered and died. Numerous attempts to restart failed. So, I went inside the burger joint to have my lunch. When I came out, (30 mins later), the car cranked up fine. So, before getting on the hiway again.....I let it idle. After about 15 mins.....it died, and wouldn't start up. I waited about 10 mins, hit the starter....and it hit several times before it caught on and ran. I then hit the hiway for the remainder of my drive, (20 mins), where it ran fine with no other issues. I did notice after it died the second time, although the water temp guage was in the normal range.......when I raised the hood....it was hot....more so than I'd would have thought.
Could this been a case of vapor lock? Are these engines prone to this? Couple things I've noticed about this car, when you turn the key to start..you actually hear the fuel pump run for a couple of seconds. Also, if the car is running, and you remove the gas cap........the car dies. Is this normal? Thanks for any help with this.

[John *.?-!.* cub owner]

hearing the fuel pump run when you first turn the key on is normal on many vehicles, though I never heard of one that would die if you removed the gascap, though that could be one of the many safety features. I suggest taking it someplace where they can read the codes and see if it tells you anything. Many places such as Autozone, will do it free, hoping to sell you parts.

[Bigdog]

I have heard of GM Onstar systems advising owner's that their gas cap was loose so I guess that an engine dying because of that is not out of reason.

[Into Tractors]

Gas cap can/will play a part on your cars system. On some cars, the yellow idiot "Check Engine Light" has been known to come on due to the cap not being tight or the gasket/cap is going bad or leaking, and I've heard of some cars not starting because of it.

Not sure, but here in Ohio you could take your cap into some autoparts store and they could check the cap to see if it is leaking?

The seal needs to be there as with the emission standards, and the vapor recovery tank, if it's leaking the computer can shut down or malfunction sometimes.

[KETCHAM]

Might be an ingition module also.They can play havoc on ya.Mounts on side of dist.Might want to check that also.Good luck!!!!Kevin

[Larry in CO]

I've also had that happen when the fuel pump was getting weak but not completely dead yet. Within a few weeks of this starting to happen, the truck finally gave up and I had to put a new fuel pump in. Not fun since it's in the tank. Larry

[Lurker Carl]

Vitamin V6 in a Tempo doesn't leave much room under the hood for hot air to escape, causing some part or another to quit until the temperature drops. One solution is to not let the car idle for more than a few minutes.

Seeing as how that car has reached the magic age of 13, I'd bet there are several things wrong that's ganging up to cause your problems. Stuff like vacuum leaks, failing sensors or relays, corroded electrical connections, weak electrical motors, cracked or broken do-hickeys that are critical to some function or another. Or even something as bizzare as the distributor cap warping as the temperature gets too hot.

The 'gas cap removal making the engine die' sounds like some component in the vapor recovery system has malfunctioned. It may also be causing or contributing to the hot idle no-start condition.

Unfortunately, component troubleshooting seems to have become a lost art. Beware, most mechanics make a small fortune replacing parts until the problem goes away.

[Hengy]

I had a '93 Taurus with the same 3.0 engine...actually LOVED that car and put over 200k miles on it. The fuel pump whirred everytime I started it, but it ran just fine. Later in its life, the fuel pump started buzzing in the fuel tank. That was just the rubber vibration insulation in the tank disintegrating, but the pump continued to work.

I did notice that when the car ran for a while in the summer it would get a little rough if I was idling for a long time, so I changed the O2 sensor in the car, and it cleaned right up. Most people don't know that the 02 sensor on modern fuel injection engines are normal tune-up items and fail long before the "check engine" light comes on to tell of a fault. If your fuel consumption has increased (efficiency down), check the O2 sensor, or better yet, just replace it...they are not that expensive, and they make your car run SOO much more efficiently!

Mike in La Crosse, WI

(P.S. - Can you believe that I actually MISS my '93 Taurus? Who could miss such a nondescript machine??)

[Harold R]

Sorry it took me so long to get back. Couple of things.......although the car is 13 y.o. it has been well maintained. It has 104K miles. The two times it died on me, at no time did I get a "Check Engine" light. I'm suspect of the fuel pump, because you can turn the switch on up to starter engage, and you can hear the pump run for a few seconds...then it quits.......maybe it has a pressure switch???? maybe loose wire...or just worn out. But I tell ya........it was about 94 degrees on Sunday and it had a lot of heat trapped under the hood.......as Carl said. Maybe wishful thinking that that was the problem.......cause like Larry said....the pump is in the tank.

[Bill E Bob]

Yep. It has a pressure switch, and when it comes up to set point
the pump shuts off. Once the engine is started, the pump kicks on
again, but you can't hear it with the engine running. Have had Fords and
GMs that I could hear the pump run up and then shut off before starting
the engine.

Bill

[Harold R]

Thanks Bill. I'm hoping that confirms vapor lock...........but, I'm on days off.....some maybe another week before I see the car again. Thanks to all opinions and thoughts. Nice to be able to share a problem and get good advice.

[Jack fowler]

Mr.Roberts,

Hopefully I can help somewhat. Follow this link with some test and illustrations I’ve documented. Maybe it will solve your issue.

If I can be additional assistance, please contact me.

Jack Fowler

http://docs.google.com/Doc?id=dcpqrttm_141hqbsh7

[Harold R]

Wow! That's some good info. I going to hang on to it. Thanks.

[DanR]

Thats NOT vapor lock. Cars have not had vapor lock since the sixtys. Vapor lock happened at high altitude on a load. In the thin air the gas going thru the carb could go below 30 degrees from evaporation and start to freeze the carb parts. You would have frost on the outside. Easy to fix just let it set until the frost melted and then gear down or slow down.

[George Willer]

Thats NOT vapor lock. Cars have not had vapor lock since the sixtys. Vapor lock happened at high altitude on a load. In the thin air the gas going thru the carb could go below 30 degrees from evaporation and start to freeze the carb parts. You would have frost on the outside. Easy to fix just let it set until the frost melted and then gear down or slow down.

Carburetor icing should not be confused with vapor lock, they're two entirely different things. Vapor lock occurs when the fuel pump vacuum causes fuel to evaporate in the line, especially when the fuel is hot. The fuel pump is not able to pump the vapor. Moving the fuel pump away from the hot engine to the tank so the pump pushes instead of pulling the fuel has eliminated most vapor lock.

Aside: A gravity fuel system like a Cub's cannot create the conditions for vapor lock because there's no fuel pump but they can suffer from icing. That's why light aircraft (all of them I'm familiar with) with gravity fuel systems have carburetor heat controls.