Share your thoughts - plugged return fuel line

[Travel'n Man]

My car has started running very rough once warmed up - almost to a shut down point at higher rpms - rechecked my floats and they were dead on - I deceided to plug my return fuel line and that fixed the problem. Full rpm's and great responce at any speed and rpm.

Here is my challange - I would rather have my return fuel line doing it's job and my railing not getting hot with sitting fuel in the railing.

1) What would have caused this error in my fuel system

2) Is it safe to maintain a plugged fuel return line

I just finished a 20 mile drive and as soon as I got back in my garage I felt the fuel rail for temp - the rear section (closest to the firewall) was the hottest and I could touch it without getting burned but it was very warm.

Share your thoughts-

[geezer]

Just random thoughts & a WAG.

I don't think you "fixed the problem" by blocking the return line, but you did create a condition that enabled the engine to get sufficient fuel volume and pressure in order to operate properly throughout the RPM range. It could possibly be a failing fuel pump or a fuel restriction in the system. Try getting a fuel pressure reading from the pump and also check for a properly working evaporative emissions system if it is still intact. If it has been bypassed, try removing the fuel cap to see if a vacuum is being created in the tank thereby restricting fuel flow. Just guesses, you have to start somewhere and you will want your fuel return line operative before the weather turns hot once again.

[jmortensen]

I ran a dead headed fuel system with no return. I ran an electric pump and had the feed line out of the fender go to the filter, and then a rubber hose off of the filter and ran that around the front of the core support and back to the carbs. Worked great.

I think the mech fuel pump puts a LOT of heat into the fuel, and the rail which is bolted to the head adds even more. By removing both of those I solved a vapor lock problem, never had it again after those mods.

[ajmcforester]

I'm with geezer on this one, also you might want to try a new filter and flush the fuel lines as much as posable before buying a new pump.

[Travel'n Man]

Found it!!

My flow guide valve was not hooked up correctly after my rebuild went in - it may not look it but that valve is important on the performance of your engine - (needless to say).

Thanks to all for guideing me through the thought process!

[Gary in NJ]

Mitchell,

Your topic has me thinking; should I check the condition of my return line? Is it safe to run a few pounds of compressed air (say, 20 pounds) through the return line to clear it of any possible obstructions?

Any thoughts on this?

[ajmcforester]

Mitchell,

Your topic has me thinking; should I check the condition of my return line? Is it safe to run a few pounds of compressed air (say, 20 pounds) through the return line to clear it of any possible obstructions?

Any thoughts on this?

Yes, I've done a lot more thab 20, I would not do it with a full tank, and remember you will make air bubbles in the tank. It also don't hurt to force some straight weight oil down the lines to prevent rust, ethanol is not your friend on these lines.