Vapor lock prevention?

Hello everyone. Hope everyone is doing well now summers around the corner. Me I’m excited every day I’m closer to getting my bird back in the road. But the temps are climbing. We’re getting closer to triple digit temps and sook will bee 100. A concern I have is vapor lock. Last thing I want is to stall out at a light or worse up a hill. My idea to solve this a cheap parts store external electric fuel pump underneath the fuel tank hooked up to relay. When fuel gets hot or when car sits flick on pump to re “prime” lines with fuel to avoid vapor lock and stalling. My question is it ok to have the fuel go through the stock pump. My only worry is if the diaphragm ruptures it’ll just pour fuel straight into the oil pan and I won’t notice until it’s done a lot of damage. What’s your all opinions? Also still debating between 144 or 200. And trying to tell of a 144 can even power AC.

dont bother with using a switch to turnn the pump on and off. use the relay to turn the pump on when you have oil pressure, that will prevent yu from forgetting to turn the pump off when you park the car, and you dont have to deal with vapor lock.

There shouldn't be a problem with turning it on and off, the Studebaker crowd does this in their cars often. But yes you're better off having it run constantly. Just dont have a high pressure one and it shouldn't eat the mechanical pump out

star is right. and if you have the system setup where the relay is energized only when the ignition switch is on, then there should be no problems. unfortunately a lot of people forget that, and just wire it to the toggle switch. if you leave that on the engine can ultimately be filled with gasoline from the tank when the pressure gets high enough to over come the needle valve.

another suggestion would be to use a pressure regulator and a return line. that way if you leave the pump on it just recirculates the fuel back to the tank, and then drains the battery from constantly using electricity.

That sounds good but how do I make a return line that sounds a little complicated. Right now I have the ignition on a separate toggle switch. I was thinking about tying fuel pump and if ignition on the same switch or ima series so that way I can’t leave the fuel pump ok unless ignition is on. Another choice is to make the stock ignition switch in the on position power a relay that then power a “circuit board” with Wires going to ignition and fuel pump. My only problem with that is if the key is in on he ignition and fuel is always on.

lotta complication'n worse - fire hazard. Don't like the ele pumps, even if in tank (but a lill better).
Y not run w/it and C.
U can gather all the info'n make a plan, even set aside the money for prts. My bet is by then you'll abandon it all.
Lets See...

FM to run a return line you need this;

https://www.summitracing.com/parts/hly-12-803/overview/

it has one inlet port, and two outlet ports. you plumb one outlet to the carb, and the other to a line that runs back to the tank, or as some have done to the inlet of the electric pump(not ideal but it works). the other nice thing is that the regulator is adjustable up to 9psi.

and as long as the pump is tied t the ignition so that when the switch is off the pump is off, and you use the regulator and return line, you should have no issues with fuel being pumped up through the carb and into the crankcase.

Yeah thanks for the info. I didn’t mean flood the bowl in the carb I meant there would be a rupture in the fuel pump diaphragm and it would pump fuel into the oil pan through fuel pump

The easy way is to use a fuel filter with a return. Just plumb it in with a "T" back to the feed line. No need to go back to the tank. This worked for me for many years.

A old member "Addo" from Australia showed me this trick. Search his name for some very useful posts.

Also insulate any under hood fuel lines.

falcon_master":3pq87c2i said:

Yeah thanks for the info. I didn’t mean flood the bowl in the carb I meant there would be a rupture in the fuel pump diaphragm and it would pump fuel into the oil pan through fuel pump

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with a mechanical fuel pump, what happens is the fuel is pushed past the inlet valve, and then the outlet valve, thus not putting pressure on the diaphragm. so a ruptured diaphragm is a remote possibility unless the diaphragm is weak to begin with.

falcon_master":1zmwp96d said:

...A concern I have is vapor lock... My idea to solve this a cheap parts store external electric fuel pump underneath the fuel tank hooked up to relay. When fuel gets hot or when car sits flick on pump to re “prime” lines with fuel to avoid vapor lock and stalling. My question is it ok to have the fuel go through the stock pump...

Click to expand...

nother shot @ it by a 'bird owner

https://www.ctci.org/gilsgarage/VaporLock.php

ive seen a lot of guys mention just running the electric and forget the mechanical and i would agree if thats what you want to do either one or the other do not do both. It puts major strain on the mechanical pump to try and pull through the electric when its not running and the mechanical becomes a restriction to the electrical so i would do all or nothing to save replacing parts consistently, the big thing would be to insulate the fuel lines before worrying about running higher pressure in the line itself

falcon_master":3uo73lzk said:

Hello everyone. Hope everyone is doing well now summers around the corner. Me I’m excited every day I’m closer to getting my bird back in the road. But the temps are climbing. We’re getting closer to triple digit temps and sook will bee 100. A concern I have is vapor lock. Last thing I want is to stall out at a light or worse up a hill. My idea to solve this a cheap parts store external electric fuel pump underneath the fuel tank hooked up to relay. When fuel gets hot or when car sits flick on pump to re “prime” lines with fuel to avoid vapor lock and stalling.

Click to expand...

That setup will work fine as long as you use a solenoid pump instead of a rotary vane pump. Using the electric pump to prime the mechanical pump (or the carburetor if it's been sitting for a long time) will prevent you from having an extra continuous load on your alternator. Adding a return line will raise the temperature of the gas tank and will add unnecessary complication. See Vapor Lock.

falcon_master":3uo73lzk said:

My question is it ok to have the fuel go through the stock pump. My only worry is if the diaphragm ruptures it’ll just pour fuel straight into the oil pan and I won’t notice until it’s done a lot of damage. What’s your all opinions?

Click to expand...

If your fuel pump ruptures, your car won't run because no fuel will get to the carburetor. A simple way minimize this risk is to rebuild your mechanical pump (if it's an original rebuildable pump). Old diagrams likely aren't ethanol-resistant so they probably won't hold up very long with modern gasolines. You can either get a kit or send it out to a place like Then & Now Automotive.

If you are using an electric fuel pump, but routing it through the mechanical pump this can also cause vapor lock. The mechanical pump heats the fuel & aggravates the condition.
The best thing to do is delete the mechanical pump & run just the electric pump.

Switching to an electric pump avoids vapor lock issues but has 2 downsides:

• Added constant noise (especially from rotary vane pumps)
• Added electrical load (could cause dim headlights at idle)

While a mechanical pump will very slightly increase the fuel's temperature, the vast majority of fuel heating occurs from conductive heat transfer from the engine block. This is why a car will be hard to restart when hot or will stall in traffic - the fuel isn't moving fast enough to carry away the heat so the fuel starts to boil at the source (fuel pump). Pouring cool water on the fuel pump can help get you going again.

[bbvideo=560,315]https://youtu.be/EppSYI8s3nI[/bbvideo]