Fuel Pressure Erratic - JeepForum.com
 
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post #1 of 5 Old 06-13-2021, 05:22 AM Thread Starter
Alientails
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Wj Fuel Pressure Erratic

Help! I have tested the fuel pressure on my 2002 Jeep WJ, 4.0, 2WD, with over 300k miles... the needle on the gauge shows normal fuel pressure when the switch is turned on, and remains steady when I shut it off. But when started, the needle literally vibrates between about 48 to 58. I'm confused as to what the specs should actually be, one page (here on Jeep Forum) says 37-41 is normal, another says 48-50. Mine is crazy. SO... do i need to replace the fuel pump, or the pressure regulator, both, or something else? I'd like to keep my Jeep a while longer!


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post #2 of 5 Old 06-13-2021, 03:55 PM
jtpeters
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2002 WJ 4.0L, FSM states:
Oil Pressure
At Idle Speed 89.6 kPa (13 psi)
At 1600 rpm & Higher 255 to 517 kPa (37 to 75 psi)
Oil Pressure Relief 517 kPa (75 psi)

2004 Jeep Overland WJ 4.7 H.O. (Bought new in Oct 2003)
2014 Jeep Overland WK2 5.7 Hemi (Bought used in 2016 w/7k miles)
1970 Ford Mustang Boss 302 (in Family since 1974)
2013 Ford Mustang Boss 302
2011 BMW 328i
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post #3 of 5 Old 06-13-2021, 04:08 PM Thread Starter
Alientails
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I'm asking about FUEL pressure, not OIL pressure! But thanks anyway...

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post #4 of 5 Old 06-13-2021, 04:38 PM
jtpeters
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Yep...I'm an idiot....I guess I shouldn't be watching golf and responding to blogs at the same time!

Fuel Pressure:
Normal operating pressure should be 339kP a 34 kPa (49.2 psi 5 psi).

My apologies.

2004 Jeep Overland WJ 4.7 H.O. (Bought new in Oct 2003)
2014 Jeep Overland WK2 5.7 Hemi (Bought used in 2016 w/7k miles)
1970 Ford Mustang Boss 302 (in Family since 1974)
2013 Ford Mustang Boss 302
2011 BMW 328i
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post #5 of 5 Old 06-13-2021, 06:27 PM Thread Starter
Alientails
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LOL! We all make errors... at my age, I've made so many that I've lost count. Thank you for the info!

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