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Adjustable Fuel Pressure Regulator
enginearin - 17/4/12 at 09:31 AM

Hello,

I've got this regulator on my Fury, can anyone confirm the means of adjustment?



I'm assuming that it's something to do with the nut on the top? lock nut with adjustment underneath?

Thanks

Tim

coyoteboy - 17/4/12 at 09:37 AM

Well, two points. Unless I'm very much mistaken you are missing the manifold vac feed from the top (brass nipple) so your injector pressure differential isn't maintained with changes in manifold pressure, and the way you adjust it is a small set screw sat under the chromed cap nut next to the brass nipple. Clockwise gives more pressure usually.

enginearin - 17/4/12 at 09:56 AM

quote:
Originally posted by coyoteboy
Well, two points. Unless I'm very much mistaken you are missing the manifold vac feed from the top (brass nipple) so your injector pressure differential isn't maintained with changes in manifold pressure, and the way you adjust it is a small set screw sat under the chromed cap nut next to the brass nipple. Clockwise gives more pressure usually.


Thanks for the quick response... i've no idea on the plumbing but, if it makes a difference, the engine is a 2005 CBR1000RR (so injected).

Where would i pick up this vac feed? Off the throttle bodies somewhere? Presumably this applies with FI or carbed engines?

Thanks for the tip on the set screw... i'll have a look under there

Tim

mrwibble - 17/4/12 at 10:09 AM

with my gsxr TBs there are vacuum outlets and hoses from each TB, which join together, i guess to equalise pressure across them. That looks like a malpassi FPR sold as "power boost valves?" don't know whether they are suitable for carbed setups but i have used one on an injected zetec before. Ideally you'll want some sort of guage to measure the fuel pressure, and ideally a probe in the exhaust for air fuel ratio.

coyoteboy - 17/4/12 at 10:12 AM

Indeed you'd need a feed from all of the throttle bodies if you're running ITBs, you need the combined average of all of them.

What ECU are you running? If it's been mapped like that then leave it but if it was mapped with the correct vacuum feeds maintaining pressure you'll end up running rich at high load.

enginearin - 17/4/12 at 11:02 AM

quote:
Originally posted by coyoteboy
Indeed you'd need a feed from all of the throttle bodies if you're running ITBs, you need the combined average of all of them.

What ECU are you running? If it's been mapped like that then leave it but if it was mapped with the correct vacuum feeds maintaining pressure you'll end up running rich at high load.


I'll have a look for the vac feeds on the throttle bodies... from memory, looking at my spare throttle bodies, there are two brass nipples on each ITB, but i don't know whether these are plumbed in on the car. I'll post some pics to ensure i have the right connection points before plumbing it in. Presumably a combined average of them just means to connect them all together? Does this mean all 8 nipples or can i take one from each ITB and blank the other? I'll have a look in the Haynes manual tonight on the subject.

The ECU is std honda, with a power commander for fuel only (as per RGB regulations). The car is new to me, so god knows what the map is... though i'm sure the engine is running rich as its fouling plugs. The guys at PDQ recommended to check fuel pressure as this is often the culprit with aftermarket regulators.

I'm going to do a power run with Pistonheads on at CFM engineering in Reading on Sunday to see A/F ratio after checking the fuel pressure is correct. It's cheap (at £35), local and i'll be able to see how far out the power commander map is. TBH i'm in the process of modifying the Honda airbox at present, so when that's sorted i'll probably head over to PDQ for a mapping session.

Thanks

Tim

[Edited on 17/4/12 by enginearin]

baz-R - 17/4/12 at 11:25 AM

the vac pipe is conected if your engine is maped to run verible fuel pressures to manifold vac.
some people go fixed and others go verible (std production cars usualy go verible tuners go fixed)
think of it as pressure diffrence between the fuel in the rail and air inside the manifold in low throttle openings the high vac is pulling more fuel at the injector than if the throttle is wide open when the pressure is near atmoperic so we ajust fuel pressure at the same amount as manifold pressure to cancel this effect.
if a ecu was maped to run fixed fuel pressure then we dont need to worry about it as its built into the values in the map.
you would pick this up by rich mixture at low throttle openings etc.

baz-R - 17/4/12 at 11:28 AM

oh and i think the ajustable bit is at the dome nut end.
slacken off the dome nut and ajust the nut under it to ajust main pressure up or down.
3 bar is the norm iirc