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carb to efi fuel system

Old 03-07-2019, 05:30 AM
  #1  
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Car: 91 Firebird Formula
Engine: 383
Transmission: built 700r4
Axle/Gears: 4.11, 9inch
carb to efi fuel system

not sure where to put this so ill use the tbi thread since im going to tbi. want to run either a fitech or holley sniper. car is originally a factory carb car. so no pump in tank. my question do you guys recomend converting to an intake pump and running factory lines or should i just throw an inline pump in and plumb it up? i like the intank idea just not sure i want to spend the money on new lines. like 100 bucks a line for pre bent ones.
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Old 03-07-2019, 07:51 AM
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Car: '90 Trans Am GTA
Engine: 305 EBL-P4 w/T76
Transmission: Stalled 700R4
Re: carb to efi fuel system

Don't waste your time with an intank pump if the vehicle did not come with one. Guys back in the day would worry, if, say, they were switching from fuel injection to carb if they needed to pull the fuel pump, which of course justified either dropping the rear, or cutting a trap door, which is a pain in the rear (pun intended). In your case, since it's already carb, just run an external pump, and mount it where the TPI fuel filter would be located, tucked away and hidden. You can use the factory feed and return lines up to where the mechanical fuel pump would be, just need to add the proper fuel regulator for the amount of psi you're planning to run, then make some fuel lines leading to the injection system (preferably GM saginaw fittings, just need a flaring tool). It's simple...

- Rob
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Old 03-07-2019, 09:05 AM
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Location: Muscatine IA
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Car: 91 Firebird Formula
Engine: 383
Transmission: built 700r4
Axle/Gears: 4.11, 9inch
Re: carb to efi fuel system

that should work. know what sizes fittings those would be at the mechanical fuel pump? probably just do an adapter to -6an.
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Old 03-07-2019, 09:19 AM
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Car: '90 Trans Am GTA
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Re: carb to efi fuel system

The LG4/L69 carbed engines should have a 3/8th feed and a 5/16th return by the mechanical fuel pump. Summit Racing should be able to cross reference them for you just knowing those sizes...

- Rob
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Old 03-07-2019, 11:03 AM
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Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
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Re: carb to efi fuel system

The LG4/L69 fuel lines can be used with an in-tank pump for the injection system. You will need the return line. 'Course we don't know what year car you have or what fuel lines are currently installed.

I installed a Walbro 255 in-tank and converted my fuel lines in the bay to quick-disconnect, factory 'nylon'. Did need to install a filter at the rear where the 3/8" feed line turns at the frame rail. Ran a filter near the fitech for a while to ensure the line was cleaned out.

Wiring for mine was simpler because the 87 LG4 had an in-tank helper pump, just used the fitech fuel pump signal lead to engage the fuel pump relay by tapping into the old lead under the dash. You'll have to run conductors for your in-line pump back there anyway though.
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