Is this the dreaded 914 vapor lock?, Asking for your ideas and thoughts Options

[Artfrombama]

Drove my 914 to a PCA function yesterday morning, 93f and humid.
After driving on the interstate at 70-75mph for around 45 miles I exited and the motor died. I had enough momentum and coasted into a gas station/convenience store where I topped off the tank and tried to restart the car, no luck. The car would fire, run a few seconds and die then refused to re-start for another 10-15 minutes then the same scenario again. No tools to diagnose or repair.
While waiting on AAA for three hours (another story) I would occasionally try to start the car with the same results.

Today, car started normally, runs normally.

1974 L-jet, original three bung fuel pump, original location.
500 miles on new tank, sock, filter, ss lines.

[GregAmy]

With a recirculating fuel system...can a 914 **really** get vapor lock?

Dead-end fuel system with carbs, sure. But L- or D-Jet...?

Discuss.

[JamesM]

With a recirculating fuel system...can a 914 **really** get vapor lock?

Dead-end fuel system with carbs, sure. But L- or D-Jet...?

Discuss.

Yes.

If it boils just in the fuel rail lines you can usually clear with with a few key cycles however if it boils in/before the pump with the pump in the engine bay you lose prime on the pump and nothing but time and cooling the pump down will get you going again.


Here is something else to think about, the boiling point of ethanol at sea level is only 173F and it just gets worse as you go up in altitude. Near 10,000 feet its only 155F

Just another reason corn gas absolutely sucks in these cars.

This is something I have witnessed and repeated first hand. There is a drive I like to take out here over Guardsman's pass that hits 10,000 feet and one of my 914s still has the fuel pump in the stock location. Warm summer days in Utah tend to hit over 100F. I always try to run ethanol free gas however there are occasions where ill go on drives, need gas, and there just isnt any around. Now if I have ethanol free gas in the tank I wont have any problems up on the pass, if I however forget that I have filled up with ethanol blend and make the same drive (which I have done on a couple occasions) I am in for a long day.

Made the same mistake at Red Rocks Classic a few years back, took the car with the rear pump out to Colorado. No issues at all on the way out as I know where to get ethanol free on the way. 2nd day of driving in Colorado I had to fill with Ethanol blend, and we were driving Grand Mesa (which i didnt realize was over 11,000 elevation) and I found myself stopped a few times dumping water on my fuel pump to cool things off.

When you have ambient temps near 100, asphalt temps near 150, an engine case running 200+ right next to your fuel pump and a component making up 10% of your fuel that turns to air bubbles at 155, it doesn't take long after the fuel flow stops for there to be problems. Sometimes you even get problems before the flow stops.

Not an issue with the pump under the tank, pump stays cooler, gas before the pump stays much cooler, and you don't have as long a feed line for air bubbles to get trapped in and all the lines that take the engine bay heat are under pressure greatly increasing the boiling temp.

[ClayPerrine]

If it boils just in the fuel rail lines you can usually clear with with a few key cycles however if it boils in/before the pump with the pump in the engine bay you lose prime on the pump and nothing but time and cooling the pump down will get you going again.

Unfortunately this won't work in this case. This is L-Jet. It does not have the 2 second fuel pump prime function that is in D-Jet.