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2004 F115 rough running and limited rpm

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  • 2004 F115 rough running and limited rpm

    My ‘04 F115 Jet Drive is acting up and can’t figure it out. It will start no problem, idles a little rough. Transition from idle to low rpm approx 1500 is rough, she’ll rev up to about 2500-3000 with no load. Also hets rough and sometimes cuts out when dropping rpm quickly from 3000rpm to idle. Checked VST screen and it was spotless and tank was spotless. Inline filter from mechanical pump to VST is clean. Water bowl filter is new. I bypassed boats fuel supply and hooked it straight to a new can and primer bulb. (Obviously I really thought it was a fuel issue). I tried primer bulb while throttling to see if maybe mechanical pump was issue. Fuel rail holds ~40psi and ~35 on idle and throttle demand. Resistance on coils is 2 and 2.1 ohms. I tried pulling each plug cap while idling and all were active. Even replaced the slightly corroded battery main cables. Compression is 150psi across all cylinders. Totally at a loss at this point as to what’s causing it. Any suggestions?

  • #2
    where does the limited RPM come into play?

    stalling when dropping to idle might be a problem with the Idle air control valve