1984 GPz1100-A2 DFI FPR?

Before buying an adjustable FPR, I better understand how they work first, and what the role is of the vacuum signal.

Does the fuel pressure delivered to the injectors increase with load?

Need I get a replacement FPR that uses a vacuum signal?

Thanks,

fuel pressure regulator has a vac line so that hte fuel pressure to the injectors is always constant. So when the pressure in your intake runners changes due to the throttle opening and closing the fuel pressure varies the same amount so that the injectors supply a constant amount and any changes are done by the ecu. So yes you definatly need a vac referenced FPR

Copied this from the msefi.com site

The vacuum referenced fuel pressure regulator is essential. It provides constant pressure differential between fuel at injector nozzle and manifold air pressure [port EFI] or atmospheric pressure [TBI]. This makes the injected fuel quantity solely a function of the injector open time.

If you were to 'cap off' the manifold vacuum port on the fuel pressure regulator, you are reducing the dynamic range of the injectors. This means you will need lower pulse widths at at (giving less control over idle mixtures) and lower flow under boost (restricting the maximum horsepower).

So, in general, for port injectors, have the fuel pressure regulator connected to the manifold vacuum is a good thing. There is very little reason not to do it (though some have argued against it for individual runner port EFI set-ups).

If you have an adjustable fuel pressure regulator (FPR), set the pressure with the fuel pump running, but the engine not running - that's your base fuel pressure (it is referenced to atmospheric pressure).

405-677-6397, ask to speak with Sid. He'll hook you up with a good adjustable regulator.

I spoke to him 2 days ago. He'll still do the Throttle Body bore as well.

This is the one I bought.
cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll...ported#ht_500wt_1214