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Thread: Possible pressure regulator problem?

  1. #1

    Default Possible pressure regulator problem?

    The fuel pressure on my Commander 950 is high, wanted to run about 26. Turns out part of the problem was some form of Loctite in the threads, I thought I had the screw backed clear "out." So now after cleaning up the threads I can adjust the pressure.

    Now I was VERY careful about assembly, and made absolutely sure the o-ring was in place. But the regulator does NOT seem to be regulating with manifold pressure. It runs the same pressure whether key-on/engine-off or engine running at idle or opening the throttle. Thoughts?

    An additional question: I may convert this to multi-port, using homemade drilled manifold, Mopar or Ford injectors, both of which I have a harness that fits the injector ends. I can build a rail. So the question is, can you buy JUST the various connectors and pins for the Holley systems, as opposed to complete harnesses? (I have not bothered figuring out yet whether I'll need a separate injector driver module or not.)
    Last edited by 440roadrunner; 11-21-2012 at 01:47 AM.

  2. #2
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    Quote Originally Posted by 440roadrunner View Post
    Now I was VERY careful about assembly, and made absolutely sure the o-ring was in place. But the regulator does NOT seem to be regulating with manifold pressure. It runs the same pressure whether key-on/engine-off or engine running at idle or opening the throttle. Thoughts?
    The Holley TBI units don't have a vacuum referenced fuel pressure regulator, because the four fuel injectors are located above the throttle blades (and therefore not subjected to vacuum). The Holley TBI fuel pressure regulator is the constant pressure type. The Holley TBI unit has a 1:1 rising rate (boost referenced) fuel pressure regulator. The air passage (under boost) is a small hole, located in the driver's side rear throttle bore, leading to an o-ring seal on the regulator housing; its purpose is for "blow-through" forced induction applications only.

    Quote Originally Posted by 440roadrunner View Post
    So the question is, can you buy JUST the various connectors and pins for the Holley systems, as opposed to complete harnesses?
    (I have not bothered figuring out yet whether I'll need a separate injector driver module or not.)
    I've done this exact conversion.
    The ECU is the same; the software just needs to be correctly configured (Engine Parameters) and the Fuel Map retuned.
    You can purchase the injector connectors & terminals here: http://www.holley.com/534-112.asp
    You can purchase the MPFI injector harness here: http://www.holley.com/534-130.asp
    You can purchase a new fuel pressure regulator diaphragm here: http://www.holley.com/512-1.asp

    My MPFI conversion, with pictures & links: http://www.network54.com/Forum/85220...old+Conversion
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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