Line off 54psi. ? Fuel pressure

[Convertedfromv8]

hey guys I have a 87 Gn , walboro 340 with a Hotwire kit.

I currently have an old school chip tuned for 93 octane with 42lb injectors, she's run mid 12s with no alky so far.

I have purchased a turbotweak chip with 60lb injectors. In the directions it says to start tuning with fuel pressure at 42psi line off. I checked my current fuel pressure and I'm at 54 psi line off !!! , seems a bit high ?

Should I turn the fuel pressure down when I swap chips initially ? Or just keep the same fuel pressure and turn it down if it's too rich at wot ? Please advise

Why do you think the fuel pressure it turned up so high ? Or is it normal ?

 

[626gn]

If you have a 340lph that could explain why your fuel pressure is higher. A few have had trouble getting fuel pressure down with the stock return line. If you have a 340m 255lph then forget what I just said. Lol.

Assuming you're working with a 255lph pump I'd start at 42-43psi line off. Just be aware that this is just a starting point. Some cars run better with higher base fuel pressures. Every car is different so I wouldn't get too hung up on staying in the 42-43 range (unless your car happens to like it) if you find your car runs better with higher pressures.

 

[BEATAV8]

old school tuning.... back in the day before you could make tuning adjustments in the chip using your powerloggger or scanmaster, guys had to use fuel pressure to increase the fuel delivery.

I would turn the pressure down to 42-45psi. Then start in the basement with the boost pressure turned down too and work your way up using the chip to tune the fueling and the timing.

Once the chip is tuned you want to make sure it keeps the tune and doesn't lose it due to lengthy storage or power interruptions. So either keep an eye on it by checking the settings frequently, or send it back to turbotweak and have your new tune settings "defaulted" into the chip so it can never ever lose it.

 

[bison]

A good way to know if the fuel pressure is correct is to look at the block learn in closed loop while cruising. It should be 128. If it's lower then back the fuel pressure down. If it's high increase it. If start at 43psi. Id rec an accurate gauge. Not those little ones that people screw onto the end of the fuel rail


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[Chuck Leeper]

If start at 43psi. Id rec an accurate gauge. Not those little ones that people screw onto the end of the fuel rail

I've checked many on my flow bench...Most all had a variation as much as 7psi.
The variance became fairly linear at the various checking pressures.