vapor lock

elwood-914 · 03-18-2004, 05:25 AM

Can anyone tell me what the symtoms are for vapor lock?

TEKWS01 · 03-18-2004, 08:48 AM

You'll know when you Have vapor lock,,, very hot outside,,ya got the top off,, just parked the ride for a few minutes,,, new girl friend in passenger seat.. key is turned,,, fuel pump makes strange abnormal noise behind her seat... and the starter just turns with the engine wanting to run for a fleeting few secconds barely able to idle... and just when ya think the the motor is going to keep going, (PHSYCH).. motor dies.. after repeated tries with the starter making terrible grinding noises as it tries to keep up with flywheel as engine is trying to run.. there is the sinking feeling in your gut as the battery starts to get weak... and the starter is groaning.. Girl friend takes off with some kid in a honda.. Then when engine cools it starts up,runs perfect..
Trust me, if you live in cali, and your pump is still back there in the engine bay, and it is hot out side,,you'll get vapor lock. don't turn your engine off.. best thing to do is move pump to front of car...

Dave at Pelican Parts · Dave at Pelican Parts's Garage

I've never had vapor lock so far, and my 74 has its pump in the stock location.

--DD

mike95125 · 03-18-2004, 11:15 AM

Your '74 runs???

calbrat · 03-18-2004, 06:32 PM

It doesn't really get hot where you live Dave...
Drive that thing out to Sacto... feel the heat.

Mine vapor locks once in a while. I just deal with it. It's hard to go through and fix the minor things on the car. I will stick to more involved things, like reconnect the front strut after that "thump" you heard at 75 mph.

elwood-914 · 03-18-2004, 06:52 PM

TEKS01, That is what is happening to my car, only on the way home, runs fine in the morning. Thanks. Lost her to a ricer huh? A couple of other things I noticed was after I shut off the engine I heard a gurgling noise coming from the gas tank? Normal? And this morning I had the car at about 4k RPMs and then I let off the gas and I noticed a gas smell, normal too? Thanks for everyones imput.

elwood-914 · 03-18-2004, 06:54 PM

Oh yeah, lately it has been dying on me when I am driving, I then let it cool down a few minutes and I'm good to go.

Duck Man 914 · 03-18-2004, 08:20 PM

elwood,

before i started working on my 75 914 project, i noticed there was a strong gas smell as well. Recently, during the restoration process, I have found a hose that comes out from the gas tank and straight down the bottom of the car. Judging from the discoloration it would appear that by design gasoline -- gasoline vapors -- travel down this tube. BUT -- at the end of the tube it looks like there used to be something attatched to it. If youre getting a gas smell, I can't guarantee you have my problem, but it's worth checking out. Especially if you do happen to find something at the end of that vapor hose. Come to think of it, if anyone knows what I'm talking about I would really love to hear from you, because it would be a pity to have everything in this car fixed up and looking better than new, yet still have this really strong gasoline smell. Thanks!

914GT · 03-18-2004, 08:41 PM

Andrew, I think you're describing the spill tube that attaches at the top of the tank. That drains any gas spilled around the filler neck out through a hole in the bottom of the car. It's unrelated to the two fuel lines to the pump and the small hose to the expansion tank off the filler neck.

elwood-914 · 03-18-2004, 08:42 PM

Andrew,

I have never smelled fuel before, just this morning. Fifth gear, about 4k RPMs and I let off the gas and smelled the fuel. Tried it twice, same thing. One of these days I will pull the tank to check the hoses. Thanks

Duck Man 914 · 03-18-2004, 08:51 PM

I think you might be right, because there IS a hole below.....

Well crap. That means the gas smell is coming from someplace else....

I've gotta get back to the garage tomorrow.. heh.

Duck Man 914 · 03-18-2004, 08:51 PM

oh, and thanks! hehe.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Quote:

Originally posted by calbrat
It doesn't really get hot where you live Dave...
Drive that thing out to Sacto... feel the heat.

How about in early July? BTDT, no vapor lock. There were other problems, mind you, but not vapor lock.

I think vapor lock is a problem very often blamed, but rarely actually there. Much like "bad gas". And even when it does happen, I believe that there are other factors that cause it, or at least contribute to it. Things like a mostly-clogged fuel filter, a fuel pump that is old and very worn, a kinked supply hose, and so on. Those are problems that should be fixed regardless---and when they are, most of the time the vapor lock will be gone.

Duck Man:
Not sure on the fuel smell. Do you have the expansion tank on top of the gas tank? Do you have a charcoal cannister on top of the tank, or back in the engine bay? Are the hoses to it routed correctly?

--DD