To Run a Return Fuel Line .....or Not

[grego37]

considering running a return fuel line in my street/ strip carbeurated mustang, in an effort to keep the fuel circulating and as cool as possible

Are the benifits that great of having a return fuel system in a carb. application?

what can I expect to gain by doing this.

I would have to:
pull the gas tank for welding work
purchase new regulator (aeromotive 13301)
purchase return line and proper fittings
route the return line back to the tank etc...

thanks

 

[rbohm]

you dont have to pull the tank for welding. just pull the sending unit, and install a return line in that with a bulkhead connector. also run the in tank portion of the return line to the bottom of the tank to prevent problems with static electricity.

 

[grego37]

thanks, good idea

 

[xoxbxfx]

what are your mods?? I dont think its going to be worth it. Lots of new cars with high pressure EFI setups dont even run return style systems...

 

[Bignose]

I would not sugest running a return system unless you are going with a power adder such as supercharger or turbo. Return system just turns your fuel system in to a hydronic heating system. Dead head type fuel system which you currently have will allow less heat into your fuel system. Furthermore opening up the cowl is a bad idea to keep your engine compartment cool. That theory only works if the car is stationary. At sppeds the area directly under the front windsheild is high preasure. This preasurizes teh engine compartment which does not allow air to come threw the radiator. The more you seal off the engine compartment teh cooler it will stay.

Eric

 

[grego37]

thanks for all the insight and info.

I have decided not to do the return line.

however, I now am going to run one of those poly moroso cool cans where I can still run my AN fittings. and run more fire sleeve where I have not on my fuel line.

 

[ron67fb]

Unless you're insulating everything after the cool can - lines, regulator, carb, the fuel will soak that heat right back up on its way to your carburetor. During cruise you will not move fuel fast enough to keep the line cool. Fire sleeve does not insulate from convective heat, only radiant heat and short bursts of conductive heat. What you want is foam insulation, like the type you see around A/C hoses or hot water pipes in your house.

If your fuel pump is rated much higher than your regulator then it should be able to supply enough pressure to prevent vapor lock. I still haven't gathered that you're actually having a problem with it. Check your fuel pressure while the engine is hot after a cruise - you do have a pressure gauge? As already mentioned there are thousands of cars out there with deadhead regulators and no cool cans on the street, plus they run 200-degree thermostats with electric fans that you'll barely catch running, no hood vents, and vapor lock is not a problem. If it ain't broke don't fix it. If it is broken, figure out why.

My vapor lock was traced to a pinched line under the car in addition to the radiator fan blowing hot air directly on the pump-to-carb line. I watched the pressure gauge and saw the pressure go up as I sprayed water on the line. As the water evaporated the pressure dropped again. But when I fixed the pinch and didn't re-route the hot line the problems went away.

 

[grego37]

Ron, everything is fire sleeved from the regulator to the carb. I do have a gauge and its always set at 6.5lbs until the 1 day I had vapor lock, it read 4lbs and the pump sounded weird, when the engine was turned off I heard perqulating.

Anyways, this was the only time I experienced vapor lock and I have now pin pointed it to the 4month + old fuel that was sitting in it detererating.

everything is fine and dandy now. and for now Im going to wrap the 6" fuel filter with a heat barrier and see if I really need a cool can.

 

[ron67fb]

Yeah mine was at 3psi but the only problem was fuel starvation at 4000+ RPM and the engine would almost stall at idle right after that. Around town the low pressure didn't cause any issues.

 

[grego37]

a buddy just sent me this informative link on
fuel pumps, regulators, return lines etc....

http://www.centuryperformance.com/fuel.asp