1- Fuel pressure regulator
2- A 15/16 in. wrench
3- Hold down the throttle lever to gain access
1- Fuel pressure regulator
2- #40 TORX socket
3- Extension
4- Hole in throttle cable bracket
5- Ratchet
Replacing fuel pressure regulator on 3.1l / 3.4l v6 GM engine. A few tools are needed to perform this simple do it yourself repair.
Leaking fuel pressure regulator can cause hard stating, stalls, gas odor, misfire code p0300.
When the fuel pressure regulator(1) on the 3.1 and 3.4 engine fails, fuel leaks into the vacuum hose
at the top.This condition causes a hard start, long crank time, runs rough when started, and can also cause a
stall condition when coming to a stop.

This also causes poor fuel economy.

Use these pictures and instructions in the replacement of the regulator.
The upper intake manifold plenum does NOT need to be removed.
The fuel pressure regulator is a vacuum operated diaphragm relief valve with fuel
pump pressure on one side and regulator spring pressure and intake manifold
vacuum on the other side. The fuel pressure regulator maintains a constant pressure
differential across the injectors at all times. The pressure regulator compensates for
engine load by increasing fuel pressure as the engine vacuum drops.
Great info! I think on my 1993 Buick 3.1 the regulator is under the intake tho?
Yes, on the older models the fuel pressure
regulator is located under the upper intake
plenum manifold.
What should the pressure be on These? i have a 2005 Monte Carlo ls with
the 3.4 and I'm reading 30 only when the engine is running. At any other
time the pressure is zero.
I think the fuel pressure should be about 45 PSI running. With engine off, if
you are showing nothing, then it sounds like a bad fuel pump.
55psi for start up, 49psi-52psi at idle, as high as 58psi through operating
range is normal
What should the pressure be on a 2003 Buick Century?
A good rule of thumb is 45 PSI.
I have the 3.1 v6 Chevy Malibu.  I took the hose off for 3 mintues, didn't see
any fuel come out to suggest a problem.  However, whenever the hose is
put back on, I can hear humming while I'm sitting in the car with it running. I
take of hose, no hum.  Strange?  Should I replace the regulator. Note: Just
did fuel pump 4 days ago because it failed, also did fuel filter and pump
relay just as a precaution.  BTW, the sound is not coming from the back or
the fuel pump, but in the front.
If this is an older 3.1L, then yes, replace the
fuel pressure regulator. There was a design
change years ago for making noise.

Leaking Fuel Pressure Regulator Replacement- 3100 and 3400 Engines

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