Replaced all the fuel lines last spring and a new Carter pump and filter this spring

Did you use a metal line between the pump and the carb?

 

A 1/4-1/2" phenolic spacer between the carb and intake is a given "standard" preventer too.

 

I never had a Vapor lock issue in a Ford.... but I had a 1995 Caddy with an LT1 that had bad Vapor lock problems real bad. The solution?? All I did was drill a good sized hole in the middle of the gas cap.... Problem solved... The car never died again...

)

Tony K.

 

Are you sure it's vapor lock? I had the same problem and it turned out to be a bad coil. Coils don't act the same cold as they do hot (leaving the key in the "on" position can damage a coil). To prove that it is vapor lock, you can check to see if your fuel is boiling. Use a clear section of tube in the fuel line before the carb, or, and this is what I was going to try, use a clear fuel filter.

 

@wolfeman haven't had a chance to bend up a line from the pump yet but that is the plan. Metal from the tank to the pump

@kenash do have a 1/4" insulator spacer; that's the thickest that'll fit under the hood w/ a 14" air cleaner

@NEFaurora will give that a try, I was wondering if maybe the tank isn't sufficiently vented

@quik I've got a clear filter in it so I can see it's definitely vapor lock; based on the minimal flow into the filter when it shuts off I'm guessing it's at the pump. Also I did have a coil related misfire earlier this year but I already replaced that

Thanks for the suggestions :smile2:

I'm thinking the best solution (until I do EFI) is probably to put an electric pump back by the tank and maybe also re-do the lines from the tank to make them straighter; would that work? For the lines I put in last year I followed the stock path so there're several bends I could straighten out.

 

do have a 1/4" insulator spacer; that's the thickest that'll fit under the hood w/ a 14" air cleaner

Try a shorter 14" air cleaner to fit a thicker spacer. May not fix your issue even with a thicker phenolic spacer. I've tried a few spacers (different thickness, materials) and still get vapor lock in hot weather if I park and come back too soon. It'll last for about a mile before it clears up. I have a FiTech EFI and not immune to the vapor lock.

 

Since my thoughts of coil getting to hot, carb spacer, fuel lines to close to block all touched on, only thing comes to mind then if no fuel in clear filter is get another fuel pump. Timing ok..

Only other small way to keep some of the heat out of engine bay is ceramic coat exhaust manifolds/headers.

I'm running a pretty stock 390 in my 67 in New England, 95 degree days no problem. Has a lot of heat. Note a turn signal hood on a 67/68, the vents on the hood are heat extractors. That helps

 

When you switch to a metal tube from the pump to the carb, consider using stainless steel. The heat transfer value is 1/3 that of steel. You could also use clear header paint, which is silicone ceramic based.

 

I had vapor lock a couple of years ago. I ended up with a 1" phenolic spacer under the carb and also covered the bottom side of the carburetor bowls with a heat reflective tape to help keep the heat away. That got me through a couple of summers until I switched to an electric fuel pump.

 

Thanks guys, sounds like an extra pump by the tank is probably what I'll go with. Will look into getting stainless for the pump - to - carb line; have also got some heat tape I might put on the line and or the carb bowls.

Headers are already ceramic-coated so under hood temps should be reasonable, seems it's just when the weather gets a bit too hot the mechanical pump isn't staying vapor-free.

 

1. Don't drill your fuel cap. If anything, in hot weather, you'll have excess PRESSURE in the tank, not suction. You don't want fumes escaping but you DO want fresh air entering.

2. Use MILD steel line from the pump to the carb. The problem with rubber (and any other line coating AND stainless) is that they don't RADIATE heat fast enough. It's not as much of an issue of the line ABSORBING heat as it is the line SHEDDING the heat. Once air gets moving the line will cool back down. Slow fuel flow at idle and hot temps will heat the line but a rubber line will HOLD the heat and won't let it go.

3. Get rid of your clear filter. If you have an Autolite carb use the factory metal screw-in filter. If you have an Edelbrock, use the banjo-style inlet with screw-on metal filter. If a Holley, use a Rochester inlet filter under the inlet adapter. Don't use any filter before the pump.

4.. Make sure the rubber line from chassis to pump and from tank to chassis isn't rotted on the inside and is stiff enough to not be collapsing, especially the one to the pump.

5. Run as much spark advance as you can without "pinging". If using distributor vacuum advance, switch to full manifold vacuum as a source. This will greatly reduce combustion temps in the exhaust and underhood heat (at the expense of some unburned hydrocarbons... a good trade-off as far as I'm concerned).

 

3. Get rid of your clear filter. If you have an Autolite carb use the factory metal screw-in filter. If you have an Edelbrock, use the banjo-style inlet with screw-on metal filter. If a Holley, use a Rochester inlet filter under the inlet adapter. Don't use any filter before the pump.
.

Thanks for those tips that's helpful; just wondering what is the reasoning for not running a clear filter? I have an Edelbrock.

Ok, 14" dia. does not translate to depth of the filter. I ran a 14" with a standard 3" thick filter and a 1/2" phenolic spacer. This was on a Eddy Performer RPM and a 1405 Eddy carb. Yes it was close, but it did "barely" clear my stock hood. One can also, install a "drop base" which allows additional clearance. I've been here done all of this......

You're right, had forgotten about the option of a drop base for the filter. I have that same carb/intake combo, currently using an edelbrock insulator pad (https://www.amazon.com/Edelbrock-9266-Heat-Insulator-Gasket/dp/B00062YBPM) which is 0.320" thick. What would work better, the insulator pad or a 1/2" phenolic spacer? Obviously the spacer is thicker but not sure about relative thermal insulation properties.

 

Another ploy, install an electric Fuel pump. This is a classic fix for Vapor lock. But, not many, want to go through the additional funds to add one.....I did early on......

 

I think a supplemental electric fuel pump on a toggle switch would be the most effective at overcoming vapor lock while you're stuck in traffic. I think heat from the hot engine block is traveling into your fuel pump and vaporizing some components of the fuel. See Vapor Lock.

A solenoid pump (like the Mr Gasket 12S) allows flow-through operation when its not running, unlike a rotary vane pump that does not. The Edelbrock 17301 is another option.

I would also consider adding some insulation between the fuel pump and the block like Canton Racing 85-010.

 

I found that adding Stabil 360 to the fuel also helps -- gets rid of the ethanol which I believe has a lower boiling point.

 

I had some hard starting issues that may have or may not have been vapor lock. I did a number of the above mentioned tricks to get rid of it, it quit happening after I went to a higher octane gasoline (89 to 91).

 

Sta-Bil 360 doesn't remove ethanol from gasoline. It is fuel system corrosion inhibitor. From the Sta-bil 360 FAQ:

HOW DOES STA-BIL 360° PERFORMANCE WORK?

STA-BIL 360° PERFORMANCE offers comprehensive protection by releasing a microscopic corrosion preventing vapor inside the fuel system that coats ALL metals parts, including the fuel tank, fuel sending unit, valves, carburetor, fuel injectors and intake manifold. It’s like fogging oil for your entire fuel system, offering “360 degrees” of corrosion protection and is safe to use in all types of gasoline – from ethanol-free fuel to E85.

RestoMike66's higher octane fuel might be ethanol-free or have components that have a higher boiling point. The extra cost of 91 octane might quickly pay for a phenolic spacer under the carburetor or an electric pump.

 

You've said that you had vapor locking but haven't told us exactly what were the symptoms. Did it stall? Or, would it not restart? When it did start, what did it take? A lot of cranking or after sitting, did it crank right up?

 

I'm having the same issue. I finally fixed the overheating. The car runs around 180 down the road and idles at 190-195 but the longer it sits and idles it starts to act up. The idle speed drops and the engine bogs until it will eventually die. It takes a little longer now that I fixed it from overheating but eventually it will happen.

 

I used to have vapor lock as well. I cured mine by going with an electric fuel pump and also adding a return line back from the carb to the fuel tank.