Joined
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45 Posts
I finally got my fuel pressure tested on my 89 xj. It's supposed to be at 31 psi but it's only running at 29 psi. Is two pounds enough to really make a difference??
Fuel pressure issue
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Unfortunately I dont have a manual, but I wouldnt think 2psi would make that much of a difference.
Fuel control system handles actual delivery of fuel to
engine. See Fig. 1. Fuel from fuel pump enters fuel rail, injectors
and pressure regulator. Based upon a manifold vacuum signal, pressure
regulator maintains a constant fuel pressure in fuel system of
approximately 31-39 psi (2.1-2.7 kg/cm �� ) by allowing excess fuel to
return to fuel tank.
Fuel injectors are electrically operated solenoid valves
which are energized by the ECU. The ECU determines injector pulse
width ("on" time) based upon input from the various sensors
1) Remove cap from pressure test port located in fuel rail.
See Fig. 3. Connect Fuel Pressure Gauge (J-34730-1) to pressure
fitting.
2) Start vehicle. Pressure should be approximately 31 psi
(2.1 kg/cm�� ) with vacuum hose connected to pressure regulator and
39 psi (2.6 kg/cm �� ) with vacuum hose removed from pressure
regulator.
3) Check fuel pump flow rate. A good fuel pump will deliver
at least one liter of fuel per minute with fuel return line pinched
off. If fuel pump does not pump adequately, inspect fuel system for a
plugged fuel filter or filter sock.
engine. See Fig. 1. Fuel from fuel pump enters fuel rail, injectors
and pressure regulator. Based upon a manifold vacuum signal, pressure
regulator maintains a constant fuel pressure in fuel system of
approximately 31-39 psi (2.1-2.7 kg/cm �� ) by allowing excess fuel to
return to fuel tank.
Fuel injectors are electrically operated solenoid valves
which are energized by the ECU. The ECU determines injector pulse
width ("on" time) based upon input from the various sensors
1) Remove cap from pressure test port located in fuel rail.
See Fig. 3. Connect Fuel Pressure Gauge (J-34730-1) to pressure
fitting.
2) Start vehicle. Pressure should be approximately 31 psi
(2.1 kg/cm�� ) with vacuum hose connected to pressure regulator and
39 psi (2.6 kg/cm �� ) with vacuum hose removed from pressure
regulator.
3) Check fuel pump flow rate. A good fuel pump will deliver
at least one liter of fuel per minute with fuel return line pinched
off. If fuel pump does not pump adequately, inspect fuel system for a
plugged fuel filter or filter sock.
Joined
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45 Posts
Hard to start, have to crank the shit out of it, poor mileage, doesnt run well at all (see my numerous other posts) 
Joined
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644 Posts
Sounds just like mine about 2 months ago. Ended up being my fuel pump. It was still working (technically) but it wasn't sending ENOUGH fuel to the engine, hence the hard starting. I could sit there for literatly 1 minute with the starter cranking and it still wouldn't start (*Note, I did not do this as I know it is very bad for the starter). But nonetheless I would definatly keep the fuel pump in mind as the possible trouble maker. HTH....Hard to start, have to crank the shit out of it, poor mileage, doesnt run well at all (see my numerous other posts)
1 - 7 of 7 Posts
