I experience vapor lock in the summer and noticed that I do not have a fuel return line at all on my '78. Can someone show me photos or tell me how to setup a return fuel line please?

I did all the engine bay cooling techniques without any real help. I do run headers and a mechanical fuel pump still. I burned up one electric fuel pump so I may beed advise on that too if I ned to go that route.

I replaced the original fuel tank with a 38 gal one.

Thanks

 

I'm unclear on what you're planning to do? Run a mechanical pump and add a regulator and return line?

If so, you'll need to pull the sender from the tank and braze a 5/16 or 3/8-inch return tube. Orient the end of the return tube pointing away from the pick up to avoid introducing bubbles.

 

I am trying to fix my vapor lock issue. I do not mind adding an electric pump back but not sure how to set it up exactly.

 

Below is a simplified diagram. Yes, run a regulator. Your system will have a return port at the regulator which goes back to fuel tank.

 

Perfect diagram! Thanks a million! One more question, does the return line go back to the tank or just circle around the regulator?

 

Nevermind, I did not read what you said correctly.

Thanks a million

 

Here's a better diagram:

 

If you stick with the stock style mechanical pump a fuel bypass can help also. With or without a return style regulator.

As posted above first step is installing a 1/4", 5/16 or 3/8" return nipple in the fuel sender at the tank. Braze or solder. A good radiator shop can do it.

To run the bypass without a regulator, you "T" the line between the fuel pump and carb. Install an orfice in the "T" with .050" diameter and hook the return line to the "T" and route it back to the added nipple at the tank in a second fuel line. You are basically introducing a small leak back to the tank. The hole in the orifice is small enough that it shouldn't hurt fuel pressure but it will keep some fuel circulating to keep things cooler and also get any bubbles or vapor headed back to the tank.

If your vapor lock happens while running the bypass will help a lot. If it vapor locks only after stopping and heat soak, bypass may help but may not be enough.

 

Thanks guys. It does seem to vapor lock more when i stop but it does do it on super hot days just driving. Now i do tow a camper with this too.

 

Has anyone done this on a dual tank setup? The only way I can think of is by wiring some kind of solenoid in the return line similar to the one already there, in parrallel so it switchs when the tank selector switch is active. Sorry for grammar just had eyes dialated.

 

How is the fuel line from the fuel pump up to the carburetor run now? If it's tucked in close to the block or exhaust side of the engine, behind stuff, it's in a hot environment.

 

Ford, AMC and Chrysler used an inline right before the carburetor fuel vapor separator, looked like an inline fuel filter with a 3rd fitting for the vapor return to tank. Things were getting hot under the hood in the 70's and up.

 

I haven't found any evidence yet of a factory or other return fuel line but I haven't really dug into my dual tank setup yet other than to reconnect the ground for the rear sending unit that was mysteriously disconnected. I did locate the valve under there once.

I know of the fuel filter you speak of but I haven't found any return lines, truck had a normal plastic one on when I bought her.

From what I know a hard line comes from the rear up to the mechanical fuel pump (Replaced that pump last year), then from there a soft line shoots up to my filter and then to the carb.

The truck does not have any evidence of any emissions control.

 

I take it you have a 3 port electric valve to switch between tanks now?
You will need a 2nd 3 port valve or 1 6 port valve but they are $$.
Right now you have 2 lines in from the tanks and 1 out to the pump / carb.
This 2nd valve will have 1 in and 2 out going to each tank. Thing is you have to make sure the retrn to the tankis going to the right tank you are pulling fuel from. If not you can over fill the other tank if it is full to start with.

You dont have a return system on the truck now so you will need to make this happen also.

Some 80-86 trucks used the 6 port valve and you can get the pig tail for it also.
The 460 trucks had a Hot Fuel Bypass. It looked like a 3 port filter up by the carb. 1 of the ports was a return back to the tank or a 6 port valve if dual tanks.
The HFB part on the carb came in 3 different port sizes but I dont know what controlled what size got what?
Dave ----

 

That sounds about like the setup I have. I can wire the valves and plumb them so they go to the appropriate tanks when selected. I was thinkin about just making the return the filter with the extra nipple for simplicity sake and just use a regulator at the carb with no return.
Anyone know where I can find that valve?

My fore tank is currently not being used as it is about to fall out of the truck. Its the plastic tank with the cage and the cage is almost gone. I do plan on replacing this at somepoint.

I like thunderhead289s idea of having the return go to the fillers instead of the tanks.