SteveG75

What I do know is that the tank was getting very warm to the touch after running the car for 30 min or so, especially with less than 1/2 a tank of gas. Fuel pressure would also start to drop.

After switching to the -8 feed line with the regulator/return at the tank, no more issues.

SteveG75

Good discussion on overheated fuel on chevytalk.org:
http://www.chevytalk.org/fusionbb/sh...d/205302/tp/1/

And another good one on fuel pressure regulator plumbing at pro-touring.com:
http://www.pro-touring.com/threads/2...lator-plumbing

This plus discussions with my tuner is how I ended up with my setup.

lionelhutz

I've seen the discussions. I've always thought there's more to the story than the car simply having a return style fuel system that is causing the issue. The reason I believe this is that for any one car that you might find on the side of the road you could find another car at the same power levels with a full return loop that keeps going.

Things like the fuel line material and routing as well as the fuel rails themselves can all affect the amount of heating. Then, the design of the pump affects how well the pump works with hotter fuel. In this respect, I expect part of it is differences in the aftermarket vs OEM testing. 20 years of EFI vehicles had return lines from the engine and they all worked without this issue, so there's a lot of history that says a return line system can work too.

I've seen the arguments that it's only big pumps because the fuel cycles faster. Well, that's almost the reverse of the stupid coolant flowing too quick through the radiator argument. If the fuel is circulating faster, then it picks up less heat during each cycle through the fuel system. So, the net heat pick-up should be similar heating for both high and low flow pumps.

Putting the pump in the tank and running the regulator in the back eliminates the second line to the front. However, the second line to the front generally isn't the hard part. The hard part is putting the pump into the tank and/or adding the return line port to the tank. There are solutions for both, but they aren't cheap. When talking about a system like the FiTech, the in tank pump solutions are over 1/2 the cost of the EFI system. So they do add a significant cost for the guy on a budget. In many cases, it's really not technically that hard or expensive to pull-off the modifications yourself with a little work, but people are scared about doing it themselves and want a proven solution. Hence the $500 to $600 in tank pump kits and both Holley and FiTech having the fuel systems designed to work without any modifications to the tank or fuel lines on many cars.

I have yet to see an aftermarket solution that works like the OEM pumps. These days, the OEM pumps are in a canister that is always filled so the pump is surrounded by fuel. It's almost like a small surge tank inside the main tank with the pump inside it. There are different aftermarket solutions to eliminate the fuel sloshing issue, but none keep the in-tank mounted pump fully submerged in fuel all the time, well except for a aftermarket custom built tank that uses an OEM fuel pump module.

You can slow the main tank heating with a surge tank like I suggested. Just put a small orifice in the return line so the mechanical pump doesn't circulate the fuel too much.

On my last conversion, I just put a sump on the tank since many of the 60's era GM cars had tanks simply too short for any in-tank system to simply install. Then, I used an external pump with a GM truck style filter after it. Which brings up another point. Any filter before the pump means you're forcing it to "suck" harder and suction on the inlet side can cause cavitation. I have highway cruised this system through more than a full tank of fuel on a 90* day a few times and had no issues with it. I've also been in traffic and basically idling for hours with it.

At the end of the day it's what works for you.

lionelhutz

I would think that all 3/8" for the fuel lines will support your power level just fine if the pump is in the tank.

If the pump is external in the back you might need to use 1/2" to feed the fuel to it. The rest after the pump being 3/8" would work fine.

You might need a 1/2" feed line if you did a surge tank like I posted or used the Holley setup posted or use a FiTech FCC. But, you might get away with a good quality mechanical pump sucking on the stock 3/8" line. In part, this would also depend on the use of the car and the size of the surge tank. The 1 or 2 gallons of fuel in the surge tank would have to be mostly used up due to not enough flow from the main tank before you would begin having issues.

gdh

FiTech, Sniper, RobbMc all say that the original 3/8" would be fine. Now if you are huge horespower you'd want to move up to 1/2".
Here's a link to RobbMc Powersurge for fuel and rtn lines:
http://www.robbmcperformance.com/pro...owersurge.html

Zip Corvettes

It is but I quoted the wrong one. I also changed it over the AN line which is what I would run, it is 3/8 but its not referred to that anymore or at least when it comes to the AN line selection. I personally would use -6 and roll with it.

gdh

72Project, found a few pics that may help you.


Sniper with stock tank and rtn (#7 are -6AN)


Using a sump (FCC, Edelbrock, Powersurge, selfmade)