Here's an amusing one for you.

Grinding up a long hill on Saturday, in ~100F weather, after about 8 hours driving in that same hot weather. Sudden loss of power, absolutely no go. The car starts decelerating. Tach starts dropping slowly; when I push the clutch in it drops straight to zero and comes back up when I let the clutch out. Pump the throttle, nothing happens.

This is, of course, absolutely in the middle of nowhere.

What do you think the problem is? How do we fix it?




. . . . . . .




What I did was pull over and stop the car on the side of the road. The wife called because she had lost sight of me. (Yay for cell phone reception!) She had pulled off at an exit and would wait for me. I tried cranking the starter a few times, but the engine wouldn't catch.

I popped the engine bay to see if anything obvious was wrong. Nothing was unplugged, but then I looked at my fuel pressure gauge. I have a nice little liquid-filled one mounted full-time in the engine bay, actually. It read zero PSI.

It had to be vapor lock--hot environment, long duration running, heavy loads, lots of heat. It pretty much matched the circumstances of when that would happen. Oh yeah, and my pump is in the stock 74 location.

I remembered stories from the old Porschephiles days of people pouring cold drinks on their fuel pump to cure vapor lock problems. Of course, you can't really get at the pump well in the stock location. But I took one of my (many!!!) bottles of water and poured it around up at the right-front corner of the engine bay. I think I actually heard something sizzle for a moment!!

Then I went back to the relay board. My fuel pump relay actually has a loose cover, so I popped that off of it and pressed down on the arm of the switch inside for about 10 seconds. Nothing at first, but the next time I pressed I heard something. Then I pressed again and definitely heard the pump run, and as I held the switch down I heard the pressure regulator make its squeaky noises. And the gauge showed 20 PSI, which is typically what it shows when I just force the pump to run.

Got back in, started the car, called the wife to tell her I was on my way, and drove off. The problem did not repeat.

Total time to fix: About 5 minutes.
Total cost to fix: About half a little bottle of water.

Whaddaya know--vapor lock isn't just a myth!

--DD

Glad to see you're driving your 914 again!

Nope, not a myth. I had it happen to me once on the way back from the Atomic Ramble. June, Arizona, noonish, 100+ degrees, 80 mph for a couple of hours, poof, no fuel. Waited about 15 minutes, got it started again & drove to the nearest place to eat & had lunch. The temp outside had started to drop by the time lunch was over, and I had no more problems.

And hopefully you can chime in the next time someone says they've never seen it happen. Carry on!

You got home, but I'm not sure it's actually been "fixed."

.

If it was vapor lock, when you activated the fuel pump relay it should have run just not pumped fuel. I suspect a relay board or a relay contact.

You should hear the pump, regardless of it trying to pump fuel or air.

In fact, the pump should get much *louder* trying to pump air ...

If it happened once, the pump will be weakened and it will happen again.

Been through this twice in the 115 desert heat.

Anyone tried to install a vertical vent tube with a manual valve near the fuel pump to release the vapors in case this happens?

I'd say just move the pump and get it over with......

Oh yeah .... hot engine, hot exhaust, release gasoline vapor ... uh huh ...

I don't think so.

Yea, one of those in 0500 traffic, downtown Las Vegas on the 15. They were sooo happy with us.

I go for long drives around here all the time and never had a problem with vapor lock. I believe its possible, but as was said before you should hear the pump either way.

to avoid the dreaded vapor lock issue (before it became an issue) i installed my fuel pump,regulator, and filter to the front trunk. and slipped every bit of exposed fuel line in taylor fire sleeve. i havnt had a single fuel related problem.(knock on wood). it also keeps the sun off of the fuel lines when its sitting at work. (gt decklid). the blue flame is my daily driver, 108 miles one way. i have seen 113 degree temps this year. my steering wheel feels flexable in those temps.

Make that hose long, up to the engine lid.
No spark, no boom.

When I was in school back in the 80's my 914 was my daily driver and took me all over the southwest. I got vapor lock all the time in the 100+ heat. My Starter would flake as well.

My Solution was to always carry:

A full tool kit
1 hammer
1 long screw driver

And ... A squirt gun full of water.

Worked every time!