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fuel pressure regulator - is it needed?
Posted: Mon Feb 18, 2008 6:02 pm
by msoultan
I have a mechanical fuel pressure regulator on my vw bus that was used w/ the stock EFI. Is there any reason to still use this device? It uses manifold vacuum to lower the fuel pressure at idle. Is there any reason the MS can't just be set to inject less? Right now my VE table values are around 67% for idle which yields a slightly above stoich mixture...
Thoughts?
Mike
Posted: Mon Feb 18, 2008 8:53 pm
by Vicoor
the fuel pressure regulator uses the "vacuum" hose to keep the pressure difference betweent the inside of the manifold and the inside of the fuel rail constant. this is what allows for the accurate prediction of the duration of injection to get the right mixture.
So, yes, you do need a regulator.
Posted: Thu Feb 21, 2008 10:53 am
by msoultan
Ok.. just thought I'd check.
Thanks!!
Mike
Posted: Thu Feb 21, 2008 5:32 pm
by 73Eldo
Edit: I got my regulator threads mixed up but this sort of fits here also....
I read on some other site that there is aftermarket EFI system(s) out now that use PWM control of the fuel pump to eliminate the need for a bypass regulator. I was unable to find any details but it would seem logical.