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Posted by: JimN73 Jun 16 2012, 07:55 PM

This afternoon outside temp was at least 94. the car took a long time to start:crank, pump, wait, pump, crank, curse, crank.

Finally started, when I finished my errand it didn't want to start again.

Vapor lock?? Is there a cure??

thanks,

Posted by: SirAndy Jun 16 2012, 08:10 PM

Carbs? FI? DJet? LJet?

Posted by: JimN73 Jun 16 2012, 08:21 PM

IDF 40s on a 2056.

I've been talking to Mark about some problems with the carbs, but they've been running pretty well lately. Thought maybe I was winning.

Posted by: flash914 Jun 16 2012, 08:32 PM

Where is the fuel pump. Move the pump to the front of the car under the tank. the pumps we tend to use like to push fuel not pull it. Gordon Sharp.

Posted by: JimN73 Jun 16 2012, 08:44 PM

Gordon, the pump is protected from the sun and the radiation off the driveway is not that great.

This has not been an issue until today, last year the car was fine during heat waves. I'm not sure that it's vapor lock and would like some other suggestions.

Thanks,

Posted by: GeorgeRud Jun 16 2012, 09:00 PM

If the pump is in the back, it is not protected from the heat of the exhaust and under engine heat, so it can be vapor lock.

Do you have ethanol laced gasoline is your area? It perculates at a lower temp and could also be part of the problem in a carbed car. I'm investigating going to an EFI setup on my 2.7 engine as it really doesn't seem to do so well with the old Webers anymore.

Posted by: kg6dxn Jun 16 2012, 09:06 PM

Put a bypass style fuel regulator and return fuel line. Then you can flip a fuel pump switch and use the fuel circulating to cool the system. Thus eliminate the vapor lock...

Posted by: JimN73 Jun 16 2012, 09:06 PM

George, the pump is in the back. The problem is that I had not yet run the car today. There was no heat from the engine or the exhaust, just the sun.

So, the question is: can vapor lock occur with just atmospheric conditions?

Jim

Posted by: kg6dxn Jun 16 2012, 09:09 PM

Yes, The boiling temp of gasoline is -45 F. So above -45F gasoline will vaporize allowing engines in arctic temps to operate. If left in the sun, your engine compartment is over 100F.

Posted by: JimN73 Jun 16 2012, 09:11 PM

Thanks, Mike.

Posted by: kg6dxn Jun 16 2012, 09:18 PM

Bypass regulator will eliminate this.

Once you have vapor lock, the vapor gets trapped in the carbs, the only way out. as new fuel hits the hot hoses, it vaporizes quickly. The only escape for the pressurized vapor is through the carb.

The bypass regulator gives the fuel an easier way to escape. The rush of fresh fuel will cool down the lines and the carbs (a little). Then the car just starts right up.

Posted by: SirAndy Jun 17 2012, 12:06 PM

Also, make sure you're using the thick FI phenolic spacers between the heads and the intake runners. This helps insulating the intakes from the heat of the heads.

Without them, you can easily boil the fuel in the carb bowls after shutting off the engine when it's hot.

Posted by: Elliot Cannon Jun 17 2012, 12:07 PM

My pump is on the firewall under the engine and vapor lock has NEVER been a problem even on the hotest days.

Posted by: kg6dxn Jun 17 2012, 12:16 PM

That's because you're tooo cooool....

Posted by: Elliot Cannon Jun 17 2012, 12:34 PM

Thank you. Thank you very much.