GMC Repair: 2001 GMC problems., fuel pressure regulator, fuel injection system

Question
I've had this very strange problem with my 2001 GMC Jimmy 4WD. It has the 4.3L Vortec with the csefi fuel injection system. It has been starting rough for awhile and the other night it finally died. I thought maybe a tune up was in order so I replaced plugs, cap and rotor, fuel filter, air filter and PCV valve. After all of this it still wouldn't start. It is getting good spark and fuel is making it to the fuel meter module at the rear of the carb. I bought a fuel system pressure tester. You hook up this device to the Schrader valve on the high pressure line. I hooked it up and turned on the key. For a couple of seconds the fuel pump hummed as it pressurized the system. According to the manual for the pressure tester the system should hold pressure even after the fuel pump switches off. It went up to about 30psi and then when the fuel pump kicked off the pressure dropped to zero. An auto parts guy told me it's probably the fuel pressure regulator. I bought one ($50) and then discovered this little device is located UNDER the fuel meter assembly (plenum). How in the world do you remove this plenum? I can get the injector electrical plug off and the fuel lines but how is the plenum supposed to come off? Do I have to remove the entire manifold? Also what are the chances that this could still just be a faulty fuel pump and if so why didn't the line hold pressure? Any advice would be appreciated. Just as a side note: when cranking the engine fuel sprays from the intake line at a fairly high rate.


Answer
Hi
The fuel pump is your problem.
This system HAS GOT to produce 60-66 psi to pop off the nozzles. The pressure regulator would have to bascially be pouring the fuel in the intake/upper plenum to only lwet the pump put out 30 psi.
ALSO the pump has a check valve on it. This is what holds the pressure. If the pump is faulty, CAHNCES ARE the check valve on the pump is also at fault.
Take the pressure regulator back and get a fuel pump.
Also the 30 psi of fuel coming out of a 3/8" hole will appear good.
I have replaced less than 15 regulators ALL for setting codes p0174/p0175. Thats it. I have never ran across one of this style leaking, because it operates off vacuum located inside the plenum.
I really hope this helps.
Good Luck
Follow post back, if needed.
Pawl