Mercury Oil Injection Alarm Beeping at High RPM's

Discussion in 'Bubba's Outboards' started by achilles555, May 30, 2008.

  1. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    I have a 1988 Mercury XR4 150. I've got her running great - but there's one last problem I can't get figured out. When I get past about 1/4 throttle, my Oil Injection Alarm starts beep - beep - beep, and won't stop until I slow the boat down to about 1/4 throttle again. It's not a constant beep, so it's not overheating. It's definitely the oil. I've replaced the sending unit, made sure that my reserve tank was full to the top, and checked both oil tanks and caps for cracks or leaks. I've also pulled the oil pump off, and inspected it for problems. Everything looks good. What's got me buffaloed is that it only starts beeping at the higher RPM's. Anyone out there have any suggestions? Thanks for the help. AC.
     
  2. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    I would say that the pump isn't putting the right amount of oil out at those R's. Sometimes this problem comes from the pump itself and sometimes its the injection line being somewhat cloged.
     

  3. achilles555

    achilles555 New Member

    Messages:
    21
    State:
    MO
    bubba. thanks for the suggestion. I went through the oil pump and even I replaced the sensor and bearing this morning. No luck. Same beeping. I do have some good news though, I think...

    I had one last thing to try that was suggested to me by a fellow Merc owner over at iBoats. He suggested switching the wire that connects to the same post on my switch box as the number 2 cylinder. He suggested removing the wire from the number 2 cylinder, and trying it on another cylinder on the OTHER switch box. That wire regulates voltage being sent to the spark plug (I think).

    Anyway, I did as was suggested...and sure enough, the beeping stopped at the higher RPM's. I'm not 100% sure what that means. Maybe a new stator? I need to find out. It's great to know that I'm on the right track, though.

    It does still beep a little, but only at about 1/2 throttle. It beeps a couple of times, then stops.

    Thanks again for the help. If any of this sounds familiar to you, let me know what your next course of action would be. AC.
     
  4. Bigjonrigger

    Bigjonrigger New Member

    Messages:
    16
    State:
    Missouri
    The oil pump is driven by a worm gear off the crank shaft. The gear on the crank is made of nylon and wears easily, as the rpm's increase it starts to slip. Remove the oil pump, put a screwdriver in the slot on the end of the shaft and hold light pressure on it, have some else rotate the flywheel a couple of times and see if you feel the gear slip.