G11 NA to Turbo fuel pump swap

Hey, As title states I’m swapping g11 turbo tank and fuel pump into my n/a. Am a bit unfamiliar with carby turbo setups, carby now keeps flooding with electric pump, have now found the Fuel pump relay from the turbo car but am not sure where the wiring runs to. Loom is pretty destroyed. I’m assuming somehow the relay lowers the voltage to the pump to lower the pressure??? any help would be great. Cheers :slight_smile:

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The relay is just a high power switch. It turns on via a low amp 12v signal from another switch. The latter is low amp and the relay then provides high amps.

Modern efi pumps can vary pressure, and such do not have a return line. Lowering fuel pressure will need a fuel pressure regulator between the pump and engine, and then, probably, a return line to the tank.

That said I know little about the G11 Turbo.

G11 CB60’s use a low pressure electric pump around 4-5psi that i know of, have shared post with a G11 guru on facebook.

My G11 factory turbo has a low pressure fuel pump (15psi max i think). This was regulated by a bypass line that was on the carby.

This bypass went to a return line that was approximately 6mm in diameter back to the fuel tank.

I bought an aftermarket carby turbo rising rate reg and replaced the bypass bleed off line with a normal banjo fitting. That would fix this issue.

My engine is still sitting on a pallet plumbed up that way. If you get stuck i can take some pictures if needed.

G11 turbo carbs have a fuel pressure reg with 6mm return line and not 4mm like the Na ones have.

Cheers for the replies, yes have changed the return line back to tank to 6mm. I think daihard3cyl might be onto the cause of the problem… photos of would be great :slight_smile:, still have the problem of the turbo fuel pump relay… have traced the wires and have matched a few going to a vacuum value?? that would probably go onto the back of the carby… not sure where the valve would go but I assume it would just plumb into the one going to the manifold for pressure, have also place the fuel pressure regulator after the carby return line leading back to the tank… hopefully this makes some sense lol!! :slight_smile:

That vacuum valve will go to the manifold for pressure/vacuum reference. Not sure about the pressure reg. Guys? Back before EFI I used DCOE webers and the fuel pressure reg was always before the carb. To much pressure overcomes the float valve. On efi the injectors need to have high pressure behind them.

haha cheers will give that a go… maybe that’s my problem running the pressure regulator after the carb :slight_smile:

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Carby is still flooding with regulator before carby. So the fuel pump relay alters the volts going to the pump? I’m thinking it must be just going flat out all the time and cant adjust or something? or does it just run flat out? and the pressure regulator is meant to alter this? sorry guys bit confused lol

Relays do not alter voltage. They are just a load switch. Like this over simplified example, you want to run spot lights. If you run the lights through a switch on the dash the switch can prob only handle 2amp, but you’ve got 50amps going through the switch and it melts. So you run the switch to a relay. Let’s say the relay can handle 100amps. The two amp goes into it when the switch is flicked and it activates a tiny coil solenoid which closes the 100amp contact point. The 50amp spotties come on and there is lots in reserve amp wise.

Early stuff like this just runs flat out. Pressure regulator limits it. The pump has fuel going through all the time because of the return line, so it can’t over heat.

You will have to make sure the carb float level is correct and that the needle and seat are closing such that no fuel gets through.

I’d suggest exactly what gormsby said.
If the seat is seating good then the pressure should still not flood.
I’d say the needle (rubber tipped) has shrunk or been damaged by fuels these days or just age.
If it’s a new needle I’d look at the seat. Most seats can be replaced also.
If it’s been sitting around it could also be just dirty.
Make sure the floats aren’t buggered and the float level is ok.
I’d start there first before you go crazy with electronics.
Ps: is this the one from me?

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Thanks for your patience guys :slight_smile: must be the needle and seat then. Have tried the original carb which I have never had any trouble with and the turbo one of the that I got from you. They all seem to over flow out the jets? then more fuel comes out the bowl vents?, will have a look at one in the next few days and hopefully its just a simple fix. Cheers :slight_smile:

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Yeah if it’s coming out the vents I’d say it’s not seating or the floats are set wrong.
I feel a bit bad now. I swear I had never run that engine. My mrs bought it and the most I looked at it was when we took pictures for you. Lol.