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Jeep Wrangler YJ
YJ General Discussion
Any performance advice for 2.5 4-cylinder?
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<blockquote data-quote="deadpool1" data-source="post: 441104" data-attributes="member: 21229"><p>the key part of this jeep engine for power, that loves to fail is the FPR. (of vast possibles) but is common this old.)</p><p>31psi at idle and 41PSI at WOT. (41 is what is possible) the vacuum in the plenum does that. Intake manifold center area plenum.</p><p>if the FPR fails , this is what happens:</p><p>if the vac hose pulled off ,fuel leaks out the FPR nipple the FPR is NO GOOD.</p><p>the FPR has 2 more failure modes</p><p>stucks open or closed as the love to do 15 years old or greater.</p><p>stuck <strong><em>open</em></strong> fuel pressure drops to say 31 all the time or even 20, and power is greatly lost. ( << hard cold facts)</p><p>stock <strong>closed</strong> the engine floods and CAT melts (2 problems now). with fuel even at 75psi can happen and is the PFR /pump shunt test spec in the FSM</p><p>a tech checks all that. The valve wears out and fails. they all do.</p><p>and the FSM leak down test.</p><p>and the injector balance test.</p><p>the enjectors can be sent out for ultrasonic reverse flow cleaning and checked for balance as a set.</p><p>finding power loss takes lots of testing.</p><p>engine , and EFI and brakes and the whole drive line.</p></blockquote><p></p>
[QUOTE="deadpool1, post: 441104, member: 21229"] the key part of this jeep engine for power, that loves to fail is the FPR. (of vast possibles) but is common this old.) 31psi at idle and 41PSI at WOT. (41 is what is possible) the vacuum in the plenum does that. Intake manifold center area plenum. if the FPR fails , this is what happens: if the vac hose pulled off ,fuel leaks out the FPR nipple the FPR is NO GOOD. the FPR has 2 more failure modes stucks open or closed as the love to do 15 years old or greater. stuck [B][I]open[/I][/B] fuel pressure drops to say 31 all the time or even 20, and power is greatly lost. ( << hard cold facts) stock [B]closed[/B] the engine floods and CAT melts (2 problems now). with fuel even at 75psi can happen and is the PFR /pump shunt test spec in the FSM a tech checks all that. The valve wears out and fails. they all do. and the FSM leak down test. and the injector balance test. the enjectors can be sent out for ultrasonic reverse flow cleaning and checked for balance as a set. finding power loss takes lots of testing. engine , and EFI and brakes and the whole drive line. [/QUOTE]
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Jeep Wrangler YJ
YJ General Discussion
Any performance advice for 2.5 4-cylinder?
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