1969 E200 with 302 v8 motorcraft 2100 carb. I'm tired of the fuel vapor issue when I try to start a hot engine after a few minutes. My plan is to add an airtex electric fuel pump near the tank. But I was just going to add it and keep the mechanical pump too. I could bypass the mechanical pump too.

Also, adding a vapor line from a wix fuel filter returning to the tank is often part of this adaptation but dropping the tank is a headache and I'm wondering if it's really necessary. I am afraid I'll lose fuel pressure via the vapor line.

My question is if adding an electric fuel pump that feeds a mechanical fuel pump is going to cause problems. AND if I should really add that vapor line return. I was going to add the electric fuel pump and see if it actually works to avoid the vapor lock by pumping liquid gas to mechanical pump that I think goes completely dry when the fuel overheats while sitting. If it works then good, otherwise I will add the vapor line because I can smell fuel vapor and hear the carb bubbling when I turn the engine off when it's hot. It needs a vapor release but I dread trying to connect the tank to the filler hose again on my back.

The carb already has a spacer and the fuel line is insulated but ethanol free fuel is not available here and this is the best plan I have.

 

Why not first try using just the electric pump by itself to see if it solves the problem?

 

It's one or the other, never both

 

Can you duct cooler air into the doghouse?

 

I think this note was confirmed as I installed the pump, no leaks at the pump end...tested the electrical...all good...fired up quicker than usual, no leaks at the pump but running slightly rough...so I look at the carburetor and it's absolutely pouring out of the throttle pump area where it's never leaked before.
So, now I will bypass the mechanical pump and test again.

 

While I was under there I realized there is a tank vent that I can use to have a vapor return line.

 

with this mechanical pump directly on the engine and above the exhaust manifold and the fan turns off when the engine is off the problem really appears when I stop at a gas station and actually pause for about 10 minutes.That is when I can smell fuel vapor and hear a boiling sound from the carburetor and when I crank it there is no fuel pressure.

It doesn't actually cause any problems when I'm driving or even stop and go traffic. the fan prevents vaporizing of the fuel when I'm moving...but when the fan stops and the heat rises in the engine and the fuel pump then the pump can't pump vapor. even when I can see there is liquid fuel in the carb bowl the loss of fuel pressure prevents it from starting again. I can get it started if I floor it and crank the starter for at least 15 seconds. OR if I shoot some starting fluid in the carb it will start and somehow start pumping fuel again.

but I would need a way to cool the engine bay with the engine off so a battery operated fan with a temperature relay and that's too high tech for this vehicle. I'm going to keep pushing for this electric fuel pump to work. I'm not sure why the carb was leaking but will report back after I bypass the mechanical pump.

 

agreed. if the mechanical pump fails, the electric pump will fill the oil pan up with gas.

 

what is the pressure of that pump? you dont want much more than around 7 PSI pressure for a carburated engine.

 

Looks like that old 2bbl just needs a carb kit with a new power valve and cover gasket
And a new accelerator pump
Clean that intake off, all spotless, where it has been leaking so you can watch it closely as you run it when you're done

 

Are you saying the mechanical pump can fail so the fuel goes directly into the oil pan through the actuator arm on the mechanical pump?

 

good advice. it never leaked there until this electric pump. I have a rebuild kit I'll throw at the carb once I test this bypass out. "spotless" is going to be a challenge.

 

This airtex/carquest pump says 4-6 psi, although I didn't test it with a gauge, and the mechanical pump is 4-6 psi so I'm hoping either a gasket failed or the combination of two pumps was too much pressure rather than the pump is too powerful for the carburetor.

 

My fuel path is not ideal but it looks to pump at 5psi.

 

Looks like the accelerator pump leaks still so I think the carb was due to be serviced at the same time as using the electric fuel pump so coincidence it failed at the same time. Or the diaphragm in the accelerator pump can't take 5psi. I'll find out soon with a carb rebuild