71coupe

In the other post, you stated:

"I have found that electric pumps will have very short lifespan if the fuel is dead-headed. This overheats many pumps, and increases amp draw significantly. To counter this, I always run a fuel return line back to the tank when using an electric pump along with the mechanical. I run the return line as close to the carb as possible, thus always keeping cool fuel circulating all the way up to the carb. I run a small restrictor oriface at the return line to keep fuel pressure up while allowing fuel circulation. This works very well, and eliminates the lean-out condition as well as vapor lock problems."

What size restrictor should I use?
Also, can you use the vapor return line for this ?(I've removed the evap canister) I just have the electrical pump. The drawing below is my fuel schematic. Should I install the restrictor near the carb & run a line to the vapor line(blue line) or just after the fuel filters (red line)?
Thanks in advance.

I'm using the Holley pump that does not require a regulator - not sure if it's red or blue. & a Q-Jet.







[Modified by 71coupe, 1:03 PM 11/19/2001]

71coupe

Duh - I just read that you said to install the restricter close to the carb - that answers that question.

71coupe

ttt

lars

71 -
Just caught your post....
I've been running return lines on all the custom systems I've been doing with electric pumps in addition to the mechanical pump. This has eliminated vapor lock problems, and has greatly increased useful life of the electric pump. All these systems have been with Holley carbs, but there is no reason you can't do it with a Q-Jet, too. On the Holley systems, I have come off the fuel pressure pipe tap in the chrome dual inlet tube assembly. This is about as close as you can get to the carb. I have screwed a Weatherhead "T" fitting into this 1/8" NPT pipe tap that has a male 1/8" NPT fitting on one side, a female 1/8" NPT port on the second side, and an inverted flare port on the third side for a 1/4" inverted flare tube. I then install a fuel pressure gauge in the female NPT port, and run a 1/4" line with an inverted flare fitting on it as a return line. I plug this return line right into the stock vapor return system if the car is equipped with one, or run the 1/4" steel line all the way back to the tank if it's not. The Weatherhead "T" fitting has a heck of a restriction in it where it transitions to the inverted flare port (about a 1/8" dia hole), and this restriction is just perfect for running the fuel return through. You'll get good fuel circulation while maintaining very good fuel pressure at the carb. If you don't want to run a fuel pressure gauge, I'm sure the straight 1/8" NPT to 1/4" inverted flare adapter has the same restriction in it.

71coupe

Thanks Lars - I'll install one in the system & use the vapor return line
:cheers:

JeffReed

Lars, I tried to do this using the original style fuel filter. I have an electric pump back by the fuel tank and then about a foot before the carb, I have the original fuel filter. Is this an effective way to have the overflow from the electric pump sent back through the return line? I really didn't think much more about it until I read this line of posts.

Thanks!!

lars

Jeff -
If you're running an original style in-line filter with the return line coming out the top, these do work quite effectively. It will keep fuel circulating to keep the fuel cool, and it will keep the electric pump flom dead-heading and burning up.

JeffReed

Cool...

Thanks Lars!