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.

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

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.

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

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.

Re: carb to efi fuel system
 

@ziggy89 How did this go? I am about half way through installing a Sniper EFI and trying to decide where to put my Walbro... Was a carb car. Doesn't even have a filter back there. There is some room under the back seat if I cut my lines, but I was hoping not to. I don't think you can near the centerline in front of the tank because I believe the rear end can go that high. Thoughts anyone? Any pics?

Re: carb to efi fuel system
 

Never ended up making the swap. Sold the car with a carb on it.

Re: carb to efi fuel system
 

Sorry for hijacking the thread I want to do this with my 84 LG4. Holley have recommended an Adjustable Billet By-Pass Regulator-6AN
Part # 12-880 and a 255 LPH Forced Induction In-Tank Electric Fuel Pump Part # 12-914. would this do away with my mechanical fuel pump in the engine bay and is my tank suitable for the pump they mention? Also could I use my existing fuel lines?

Re: carb to efi fuel system
 

mine was easy because it was a carb car. I assume yours is fuel injection. Likely why they recommended the in tank. If your carb I wound recommend pulling the tank. Well, it would be quieter then my inline, but I didn’t pull the tank. Just replaced a my old rubber lines and plumbed in the pump. Mine has been working great. I used my 1/4” return. The regulator seems a little odd too. The sniper has a regulator in it. Wonder if the pump they recommended needs more control.

Re: carb to efi fuel system
 

Mine is a carb car also. Easy way would be to plumb an in line pump like you said. However if my tank is able to use this pump i would prefer doing that it just confused me as it said the pump fits 85-92 and mine is an 84.

Re: carb to efi fuel system
 

With carb, your current pickup does not have a pump mount on it. My understanding is that you can keep the tank, but replace the pickup assembly with a later mode like 85-92. That will give you the holder section for pump and power ground leads. It should be quieter that way. Mine is pretty noisy with the walbro unit I have. I don’t really care though. Sniper has a blue power with that goes from front to back. Just frame mount the group (test that it is a good ground). I just drilled a hole above the hump behind the carpet. Put a grommet and some shrink wrap so it stays safe.

Re: carb to efi fuel system
 

If i went for the inline pump and left the tank as it was would this kit be suitable and contain what i need would you think:

https://www.holley.com/products/fuel...parts/550-868K

I can't figure out why holley did not recommend this to Me. I think they may have thought as said that my car was injected

Re: carb to efi fuel system
 

yes, that is basically what I used. The only thing is you may want to get under and make a strategy on where to put it. I put it vertically right in front of rear axle and behind drive side rear seat. It is right below the current vent. Replace all! The lines back there. They are only and you are under there already. Make sure your tank vent is functioning. They aren’t replaceable so disassemble and clean. YouTube it. Use vapor lock fuel line or better. Use their clams too. I assembled the fuel from my own parts. I just got the base kit. I didn’t need some of the items they had in their kit. I used 90 elbows up at the body and plumbed to original hard lines. I only have about 350 hp so I have had no problems with flow. I wanted to get two pressure gauges on each line up front but ran out of money and just tried it. Worked out fine. I did do the Holley pro dash for my gauges. Hooked right up to their CAN bus and worked great. Pricey but really cool. Back in the rear I drilled 3 holes. One for 12v wire, 2 for mounting pump. It is tight. Took me a lot of time to find just the right spot. Oh and I put my after pump filter in the hump below the back seat. I couldn’t fit it all together in back. So, hard line off tank, pre filter, pump, hardline under, post filter. Sorry can get photos for you. It is in storage for winter.

Re: carb to efi fuel system
 

I know threads old but looking for more info on 87 with lg4 ls swap with inline pump i also have corvette reg./filter too.