MFI Fuel Filter w/Carbs?

[Neunelfer]

Hey Gang,

I'm running my 2.5 in my 911 while I build my 3.0 MFI motor.

I need a fuel filter in a bad way.

Thinking of the pending MFI install, would it be possible to hook up the fuel filter in advance and run it with my Webers? How would one do so?

Thanks,

E.

[MoparBoy72]

I don't know why not. Here is a diag. that may help ya; also you should have a fuel pressure regulator in the system (pump dependant).

[edmayo]

Be aware that one of those banjo fittings is a check valve, remove them and look in the end, should see a ball and spring, don't think you'll need that with carbs.

[Neunelfer]

Thanks Andrew and Ed,

So, from the looks of this I would simply disengage the cold start enrichment and plug the MFI Pump return line.

Do you guys forsee any problems with that for a temporary set up? Talk to me about a regulator. I got the last new Bosch fuel pump my supplier had last year but it's not an MFI pump.

[orange911]

I am no expert on this topic, but have you found the pressure rating of the fuel pump? I know the MFI pump is out of the equation, but I would feel better knowing the pump isn't rated for 5 bar (75 psi). A carburetor needs much less pressure, and thus may not be designed/able to restrict the higher pressure. By comparison, my old SU pump for triple SU's is rated for 3 psi.

[mjmoran]

The MFI pump and pressure rating is too high for the carbs. You will need another pressure regulator inline to bring it down to 3-5 psi

[Neunelfer]

I have the carb pump on the car now... everything is working fine. I just want to plumb in a better filter and I have this one sitting on the bench staring at me.

[mjmoran]

Eric,

in that case, there will be no problems...

[edmayo]

The best regulators that I have used are the Holley regulators. They are of a higher quality than the common $10 one most people tend to use. They used to come in two different ranges, as long as you aren't using the MFI pump which will put out about 40 psi the Holley regulator should be able to bring it down to the 3-4 psi you need for Webers. Try Summit racing and check the specs for the regulator range.

[mjmoran]

I agree, the Holley is one of the better ones. The one to get is their adjustable one with a recirc. circuit in it. I don't have the PN, but it should not be hard to find...