I have a 78 f250 4wd 400 auto.

Last summer i still had a vapor lock issue on hot days, all the sudden, dead. No fuel, i would like to resolve it before this summer.

Is this motor (mostly stock) notorious for vapor lock.
I run headers, but they are not close to the fuel pump.
I run a 3/4 black walnut spacer under the carb and blocked off the EGR.

still getting VL on hot days.

considering a new aluminum intake and holley,, discarding the old two barrel and cast iron intake.

thanks,
Chris

 

You could try clothes pins clamped onto the hard line between the pump and carb, they act as a heat sink, keeping the fuel cooler.

 

... are you running a hard line between pump and the carb (last little bit for a filter is ok)? (if that is all rubber, go back to hardline or use a smaller diameter rubber line to decrease/eliminate your vapor lock). worked for me. The smaller the diameter line the faster the fuel runs up the line and doesn't get a chance to heat up.

Insulated fuel line would be next:

https://www.pegasusautoracing.com/pr...EfShoC7Mrw_wcB

If all else fails, install an electric fuel pump which will generate enough pressure to push the vapors through the carb at all times. :-)

 

Put some pipe insulation over your fuel line, be it hardline or rubber. This will help especially if you can find reflective pipe insulation, otherwise just use regular pipe inulation - the sort of stuff you see on houses hot water pipes.

If and when you do an intake swap, make sure you have a valley pan. This will keep hot oil off the intake altogether and is an older performance trick - keeps the charge a bit cooler.

Cheers - boingk

 

I like the clothespin idea. If you're doing laundry, hell they're right there and everythang.

 

Electric fuel pump time. Todays gas sucks.

 

I went electric pump set somewhere between 5 and 6 pounds and it fixed this for me on my latest project. Be sure to pull the old pump and plate it off though for you won't know it when the old pump in place starts to fail and starts messing up the mechanicals under the timing cover. And all mechanical pumps create wear and eventually fail...

 

The gas sucks, the mechanical pumps suck, the electric pumps are junk... Hm.

Seriously though aren't the electric pumps kinda noisy? Like everything else, good parts cost a little bit, and electric motors seem to be all over the map in terms of quality.

 

Double check condition of the lines. Any small leak or soft collapsed hose will want to lock it up.

That said, the "robust" fix is an electric fuel pump mounted low on the rear frame rail where it is cool. This completely fixed hot weather vapor lock for me. By putting a little pressure in the line where it gets close to the engine, no bubbles.

A Mr gasket mini pump will do it for a stocker and a Carter pump is a higher flow option.

 

I was having vapor lock on my truck a few years ago. I looked up online for a fix for these and it seemed that Ford recommended going to a lower thermostat setting, a 192 or lower. I did that and it solved my problem.

 

I will go back over my fuel system when i get some garage time and check all of the lines.


As for an electric pump. I have dual tanks, not sure the easiest way to convert. maybe a pump for the main and a transfer pump from the AUX tank.

 

Quality header wrap, insulate the fuel pump with the sticky foil tape, like used in heating and air duct work.

Follow advice on fuel line material changes. Make sure you have a fan shroud to get the air funneled into the eng compartment.

Route the fuel line away from hot items, headers, heater lines and see if you can work out the shortest route as possible from pump to carb.

 

I installed a Carter external electric inside the frame rail, just ahead of the tank selector valve. No more vapor lock. I can hear the pump "pump-up" when I turn the key, but there's no offensive noise when running.

And no place in the US gets hotter than Yuma!

https://www.ford-trucks.com/forums/1...-the-79-a.html