Routing Hard Lines - Trans Tunnel or Frame Rail?

[73Inka2002]

Hi everyone,

Just want to get a quick feel for where everyone is routing their hard fuel lines on vehicles that didn't come equipped with factory EFI. I'm not sure if the transmission tunnel is best (up and out of the way) or if most just route along the underside of the body or frame rail, etc.

Thanks!
Robert

[patrickbrown]

Mine are run just to the inside of the left side frame rail. I made sure that they never dip below the lowest point of the frame. You don't want to accidentaly crush them with a jack or speed bump.

[fury fan]

On a lot of vehicles the exhaust is closer to teh trans tunnel than to the rockerpanel or framerail, and it would be preferable to avoid the exhaust in case there is ever a fuel leak.

I'd recommend to follow the OEM practices/gemeplan, they've put far more thought into it than we ever could.

[Six_Shooter]

I will usually run the new fuel lines in the same location as the original line(s) were.

In the case of my Datsun, this meant in the trans tunnel.

On my Jimmy, this was along the frame rail.

If you plan to race your car, check with the rules of the sanctioning body that you will be racing in. In a few I have seen that the fuel lines can't be run through the trans tunnel, unless OEM placed them there.

[73Inka2002]

Thanks guys, good info. I think I've found a nice clear safe path along the frame rail.

[a73camaro]

On a '73 Camaro I used the factory 3/8" steel line. I swapped the mid rubber coupler with high pressure rubber hose. On each end I put on a AN to steel line connector. I used the gas tank charcoal canister vent for the return.

[Mike_Robert]

Six Shooter: I like your response a lot!

[kjones6039]

A quick point if I may.........

When installing or replacing feed/return lines make sure the return line is large enough to accommodate the fuel returned to the tank from the regulator. IMHO the return line should be the same size as the feed line when possible.

I learned this the hard way. (the way I learn most things!)

I tried to use the stock 3/8 feed and 1/4 return line on my 79 Corvette. Bad idea! Holley told me to use at least 5/16 for the return and insure that the pressure on the return side was less than 3 psi. When I was done I had 14 psi on the return side of the regulator. Needless to say this caused me a lot of problems when adjusting high-side fuel pressure. I am now changing the return line to 3/8. A PITA but it has to be done!

So much for cutting corners!

Just my 2 cents worth guys.....

Ken

[Six_Shooter]

Thanks Mike_Robert.

A quick point if I may.........

When installing or replacing feed/return lines make sure the return line is large enough to accommodate the fuel returned to the tank from the regulator. IMHO the return line should be the same size as the feed line when possible.

I learned this the hard way. (the way I learn most things!)

I tried to use the stock 3/8 feed and 1/4 return line on my 79 Corvette. Bad idea! Holley told me to use at least 5/16 for the return and insure that the pressure on the return side was less than 3 psi. When I was done I had 14 psi on the return side of the regulator. Needless to say this caused me a lot of problems when adjusting high-side fuel pressure. I am now changing the return line to 3/8. A PITA but it has to be done!

So much for cutting corners!

Just my 2 cents worth guys.....

Ken

My Datsun originally had a 5/16" feed and 1/4" bypass/return line.

I retained the original feed line and used it for the return line, then added a 3/8" feed. I figured that since GM set up most of their EFI fuel systems this way in the '80s and early '90s (and later), then It should support my needs.

When we injected my Grandfather's '71 Chev pick up, we added a second 3/8" aluminum fuel line, since 5/16" aluminum seemed difficult to find. Seems to work well on the Crossfire TBI system we are using.

I do agree that return line pressure should be accounted for when designing a fuel system.

[73Inka2002]

More good info, thanks guys! I bought a roll of 3/8" hard line, so I'm using it for feed and return. Doing a -6 sleeve and nut on the hard lines and then I'll just do a nice -6 line to my FPR, fuel filter, fuel rail, etc. Nice and simple. Probably expensive to do all -6 lines, but whatever... you only live once.

Thanks again!
Robert