[V8] Fuel pressure gauge

[Craig Nicol]

<snip>Has anyone installed a valve on the fuel rail to measure fuel
pressure? I thought I read about it somewhere.  The AF TWiki has one for
S4/S6 cars.  It was an incredibly valuable tool on my previous cars and I'd 
like to have one to check numbers. <unsnip>

Yes, I've installed a fitting on my S6.  I've also seen folks who have
modified their V8 fuel rail for the fitting.  I cut a rubber section of the
fuel line near the fuel filter, installed a brass tee with two
hose-to-pipe-thread fittings. The third leg of the tee to a brass Schrader
valve.  You have to use FI hose clamps on the hoses and a metal valve cap on
the Schrader valve. The valve has a 1/4" flare fitting that's the
most-common standard for EFI pressure gauges. The magic part is the valve
and it's NAPA # 209459 and I paid $3.74, (jobber price). FI clamps are
705-1226 or 1227 depending on hose diameter (14 mm and 15 mm).  I've often
wondered why so many guys on the list just replace the FPR without checking
the pressure.  FI pressure is critical, the ECM accepts it as a given
pressure and if it's off open-loop will be fat or lean and closed loop may
not be able to squeeze the injectors enough to keep the engine from running
fat. 
Craig N.
90 V8 Q
95 S6 Avant