Ironhead38

Trying to figure out if I need the tank fuel pump or not in my 383 stroker swap . I'm looking at the 86 Chevy service Manuel as I'm typing this and it says the L69 and LG4 engines both use mech fuel pumps with the L69 also using the tank pump also and says nothing about the LG4 using an electric tank pump . I do see the fuel pump relay on the firewall , should I remove the tank pump and go just go with the edelbrock fuel pump I have now ?

Ozz1967

iTrader: (4)

that depends on what you want to do? Are you going carbed?

I actually got rid of my mechanical pump and installed an in-tank pump and put a regulator in line with it to bring the fuel pressure down.

On cars with the dual pump set ups, the mechanical and in-tank pusher pump (3psi or so), the mechanical pump can pull through the dead electrical pump in the tank but it's hard on the pump and not advisable.

Is your wiring and relay good? that may go a long way to deciding which way to go.

dmccain

iTrader: (2)

I would pull the electric in tank pump out and go with the manual pump just because its such a job to drop that tank and change it every time they quit. Ive heard the manual will pull through it but like before mentioned it is hard on the pump if you drive it a lot.

Ironhead38

Yes , engine is carbed with a 770 street avenger electric choke and was also wondering about the fuel return line , should I just plug that up ? . And last do I need to put a regulator in before the mech . Tx for all the info .

Night rider327

iTrader: (13)

With a carb, just use a block mounted mech. fuel pump. With it being a performance engine get you a carter, summit, holley 110-130 gph mech. pump, or a parts store replacement pump for a 1970/71 LT1 350 370 HP camaro.

If you get the 70/71 pump it will have a return line port on it... If you get one of the others you can buy an inline fuel filter with a return line on it.

Damon

The LG4 got the in-tank "helper" fuel pump in 85, I believe. The L69 HO cars always had them. They aren't enough to feed the engine all on their own. That's what the factory used them IN ADDITION TO a traditional block-mounted mechanical pump. They were used mostly to help prevent vapor lock in hot climates, not because the engines made so much power the mechanical pump alone couldn't keep up.

If the in-tank pump is dead (likely) you should remove it and replace with a piece of fuel hose. A non-running electrical pump presents too much restriction for the mechanical to draw through under high-demand conditions (WOT).

Ironhead38

Wow great info thanks

Ozz1967

iTrader: (4)

You're probably correct, though when I pulled my tank I found I had an in-tank pusher pump that didn't have any wires hooked up to it. It was clipped at the rear quarter where the chassis harness meets the sender harness. The only lines hooked up were for the sender reading. I ran like this for 8 years and can't say I experienced any issues.

That said, this was on the original 305 and not a true high performance application.

RamIt

My 84 L69 does not have an intank pump. The fuse block has a spot but there are no wires connected where the fuse should have gone nor is there a relay in the engine compartment.

My car suffers from fuel boiling in the lines where it runs next to the headers even though they are wrapped. Gotta love the oxygenated gas.


I will be installing a TPI intank pump to replace the mechanical with a return regulator. Higher pressure in the lines raises the boiling point hopefully enough to cure it.

Ozz1967

iTrader: (4)

I think they were a dealer installed option. I mean, mine had one on stalled, has the connector, wires and everything that goes up into the engine compartment but I could never find where they went. I can't find the relay and my fuse box, like yours, also has nothing in the "Fuel pump" part...it's just empty.

I would occasionally have fuel issues when it got really hot in New Mexico and I was stuck in traffic.

When I installed my new motor, I installed a 255lph pump in the tank and ran a painless fuel pump relay harness. I have a mallory 4307m return style-regulator to bring the pressure down.

5 years now and zero issues with it.

DonW

Ummmm...Fuel boiling in the lines next to the headers? Why not save your skin and reroute the fuel lines?

naf

iTrader: (7)

If you maintain the stock fuel lines, you will NEED the to keep the return fuel line operational. It recirculates fuel to keep it cool. Block mounted pump alone will work, Carter M6626 (like $13 at RA) is a recommended replacement.

If you have the in-tank pump, I'd recommend keeping it. This pump will clear the lines of any fuel that may be vaporizing before start up.

Re-routing fuel lines is a good idea, but I'd still retain the return.

five7kid

iTrader: (14)

'87 was the only year 3rd gen LG4s got the in-tank helper pump. If an earlier LG4 car has it, it was installed by a dealer as a vapor lock fix.

Damon

five7kid- Thanks for the correction. You're right. 85 was when the LG4 got higher compression and a knock sensor like it's L-69 big brother. 87 was indeed when it got the in-tank helper pump.