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  1. #1

    Default Fuel system question

    I am completely redoing the fuel system in my car and updating everything to 6an lines. I am doing a full wire tuck as well so I want to keep the engine bay as clean as possible.

    My question is how to setup the remove fuel pressure regulator on the car, a return or deadhead setup?

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    what are the benefits/drawbacks of each one? I am leaning towards a dead head as that will keep things cleaner and only have one fuel line going to the engine.

    Here is a photo of what I am working with.

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    1986 SVO 1E (IRS'd and too much $$ spent making it turn, stop, and go)

    1979 Pace Car #2179 (Gathering parts for GT500 5.8, T56, and t-top swap)

  2. #2
    Moderator wraithracing's Avatar
    Join Date
    Jun 2010
    Grand Junction, CO/RR TX


    I don't know that I can give you specific details for each system. I just know that in V8 systems the dead head setup always has some issues with fuel pressure and flow the injectors at the end of the run. I believe this is generally as HP/TQ output increases, but that is one concern. The other concern with the dead head setup is fuel temperature in the rail and the fuel pump stress. In the open system you are always returning fuel to the tank, so you have constantly fresh fuel that doesn't heat up sitting in the rail when the vehicle is a low speeds or low RPMs. I know there are arguments that the constant flow adds heat to the fuel also. The issue with the fuel pump in a dead heat system is the stress due to pumping pressure into a fully pressurized/filled system. The return system generally will not have the added "back pressure" for lack of a better term. The fuel constantly flowing through the pump can also help to prevent the pump from overheating. That's all I have to provide or at least mention. Good Luck!

    "I Don't build it hoping for your approval! I built it because it meets mine!"

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  3. #3
    FEP Super Member erratic50's Avatar
    Join Date
    Dec 2016


    in the 90's I was actually struggling with vapor lock my V8 86GT in hot weather. It was SERIOUSLY frustrating because it was my only car at the time.

    The issue is exactly as Trey described -- added heat in the fuel.

    The main parts of my problem were that I had foolishly bought into the 255 lb/hr fuel pump / bigger is better argument. Many videos have been published by top parts suppliers on why such a large pump in a stock hanger is just BEGGING for problems. Yep ...... problems confirmed.

    I had fuel running laps through the fuel system like it was going out of style. And, of course, suffering from drivability issues because when my foot wasn't firmly planted on the floor the return line wasn't big enough to keep up with return demand. Fuel pressure went sky high as the return line became the acting "regulator". It is a wonder that I never blew out my crossover line at my fuel rail! I did blow out my high pressure rubber lines multiple times in the rear which is ultimately what caused me to discover where my problems were. VERY fortunate that I did not burn the car to the ground on that deal !

    Another consideration ...... fuel lines at the rear of the car are *so* close to the exhaust on a V8 car. this inherently contributes to the heat problems.

    Granted -- I was mainly only encountering vapor lock issues if I let the car get below 1/2 tank and when it was 100+ outside and I was driving over black pavement that was undoubtedly 130+ and did so for some distance.

    I could "fix" it by finding a gas station with their fuel tanks in a shady area and filling the car back up. Around 2-3 hours of road time later it would be back down to 1/2 tank and vapor locking if I didn't put it into 3rd and plant my foot for a mile at least once every 3 miles. Aggravating to say the least.

    One of the other HUGE contributing factors was ethanol blended fuels. That's because of Alcohol's low boiling point that's barely over 100 degrees. Running premium without any ethanol blend helped considerably -- its evaporation point is much higher than ethanol blended fuel as well as lower octane fuel.

    I think there are some lessons in there which is why I'm sharing.

    1 - never -- ever - oversize a fuel pump larger than is needed to support the maximum output of the engine application or the fuel supply and return lines. 190 lb/hr is the outer end of what the stock hanger and return lines will put up with. After that you're going to have to get serious (as you are doing). Some will say repurpose the supply for return and run a new supply. Others say abandon the factory lines entirely.

    2 - well controlled and fully known fuel pressure at the fuel rail under any and all types of throttle positions is a BIG priority in a fuel system. Fail at this and you'll either blow your car up or fight it at every turn util you figure out what is wrong. (speaking from experience!)

    3 - It is NEVER a bad idea to insulate the fuel lines and tank to keep the fuel as cool as reasonably possible

    4 - fuel temperature at the injector rail should always be THE priority. Fail to control this and you'll suffer weeks or months or years of frustration in various conditions before you figure out what is wrong

    5 - A wise man keeps his car full of cool fuel in the summer if he wants his fuel pump to last more than a few seasons at a shot. (Knock on wood I have not touched my fuel pump on my 86GT in over 200K miles now)

    Hopefully these things are helpful to you

  4. #4


    I appreciate all the info above and will take the advice to heart. The only thing that is staying from the original fuel system is the tank, everything else is brand new and set up for E85/flex fuel and around 400-ish hp, some items maybe a little over kill but that is not a bad thing imo. I want to make sure I do everything right as I have already had to buy a couple things over by not fully researching what I needed.
    1986 SVO 1E (IRS'd and too much $$ spent making it turn, stop, and go)

    1979 Pace Car #2179 (Gathering parts for GT500 5.8, T56, and t-top swap)

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