In Tank Fuel Pump

[Ernest]

Would it be possible for it to function properly in a non baffled(original) gas tank?

I would like to go with an electric fuel pump just for carburated use only and ditch the mechanical, some have suggested in the past about using a "vega" pump.

From what i've read, it puts out around 6psi, so i should be able to use the existing factory 3/8" hard line and run it straight to the carburator without the need for a return line, or would it be a good idea to have that return line anyway?

The intank fuel pump assembly i'd like to use - https://ecat.spectrapremium.com/en/parts/SP172A1H

 

[81cutlass]

If its a carbed street car that you don't plan to take on really aggressive turns or launches at the track? 99% chance you'd be fine (made up statistic haha)

An in tank electric pump is no different (probably even better since it has a good quality fuel wicking sock) than a mechanical pump on the block or an in line electric that thousands of hot rods use. You have a higher risk of fuel starvation on fuel slosh vs. a baffled tank but if the pump picks up some air for a fraction of a second it will just bleed out the vent on the carb and the carb has a big enough reservoir that the carb won't starve fuel.

EFI will cause an issue if it sucks air as there's no air bleed built in the system and a drop in pressure can be really bad for the engine. Carbs are much more forgiving.

The biggest issue you are going to have is knocking the fuel pressure down to 6psi for a carb. That spectra pump is for TBI style cars and has an internal relief at 25ish psi. You need to run an external pressure regulator at the engine or at the back of the car. Back of the car you can get away with a foot of line looping back to the return, at the engine means running a new return line all the way back or reusing the stock feed line as the return and running a new feed line up.

Personally I'd put a carb regulator under the bump in the trunk floor and run a 1ft hose to the feed and return on the regulator and cut the OEM steel feed line back a few feet and connect it to the carb regulator. Set and forget.


Your milage may vary. I am a self proclaimed hack. The 'do it right the first time' crowd will likely say it needs to be baffled with all new hose but it's such an edge case where you'd never notice an issue I'd take the risk.

 

[stew86MCSS396]

If you like hacks...I seem to recall someone in the EFI realm used an old Lucas Fuel Additive bottle modified to provide the baffling for a tank that didn't have it.

 

[64nailhead]

We ran a Vega fuel pump with a carb’d 327 with no return. It worked but wouldn’t make it a fuel 1/4 mile before the bowls were empty. But worked great for street use and 8-9 seconds at WOT - 300whp and 380 wheel torque.

It made only about 4.5-5.5psinif fuel pressure, but that’s plenty for lost every carbine ever seen. The pump was reliable for over a year. And wiring it was pretty simple with a factory oil pressure switch to turn it off if the motor shut down unexpectedly.

 

[Ernest]

Thanks for the replies.

81cutless - the spectra premium fuel pump assembly doesnt include the electric fuel pump, i'll have to install one seperately. My malibu will not be used in autocross or drag racing, just normal driving conditions and if the day ever comes i decide to go EFI(edelbrock proflo4), then an aftermarket made for g-body baffled gas tank will be used.

Stew86MCSS396 - thats sounds interesting, a home made baffle for a carbureted gas tank.

64nailhead - street use is all im interested in, the vega pump should be more than enough for my needs for a returnless system like the OEM did, and i'll be sure to run the electric pump through a relay and a oil pressure switch for sately reasons. To be honest, i wouldnt mind going straight for a baffled tank, but i've read the only issue is, that the fuel filler inlet tube is a bit short or not in exact placement like the original. Possibly having to remove the aftermaket filler neck and replace it with the original OEM tank filler neck or cut it near the tank and use a fuel resistant large diameter rubber hose to correct the length. Descisions Descisions

 

[Clone TIE Pilot]

When GM used to sell a ZZ3 350 swap kit for LG4 and L69 Thirdgens F bodies, the kit included an intank electric fuel pump and a return regulator that bolted on the engine at the mechanical fuel pump mount. The regulator which looked like a typical Holley unit reused the original fuel supply and return lines. Mounting the regulator at the front allows for easy pressure adjustment. Also with this conversion you may want to install a universal impact shutoff switch.

http://www.camarotech.com/engine-ZZ3.html