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Thread: Help on Low Water Pressure CEL?

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    Default Help on Low Water Pressure CEL?

    Had the boat out today and the Smartcraft Monitor was giving me a "low water pressure" warning. (Optimax 200) The engine seemed to be operating normally, the engine temp was normal, about 73 degrees F. Water pressure was reading around 7 psi at 4,000 rpm, but also under 1 psi at idle. Can anyone provide any insights as to what the problem may be. Actually I'm not exactly certain as to what water pressure this is sensing, I assume cooling? If I hadn't had the monitor I would have had no indication that anything was wrong. Any thoughts would be appreciated.

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    Member Dupont Spinner's Avatar
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    Jet or Prop?

    Yes it is reading cooling water.

    So it was peeing water out the witness ok...even at idle. The 73* seems a little low, will have to see what I can find out.

    Try flushing the system with the garden hose and adapter. You may even need to remove a hose on the block and reverse flush. May have some debris caught up in the system. I think it was last year that TBloomA had the same issue with his and we flushed with the garden hose and got it cleared. Last but not least may be time for a water pump.

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    Jet, I'll give the flushing a try. Thanks for the quick response.

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    Member jeff p's Avatar
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    Default merc

    Yes it is sensing water pressure & the 1st question is how old is the water pump impeller?
    they dont last forever. The sensor has been known to fail at times but my guess would be on the water pump just getting old. The sensor sends a 0-5 volt signal based on the pressure.

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    Only have 40 hours on it... so I would hope it isn't getting aged.

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    Member Crumm's Avatar
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    Quote Originally Posted by Dupont Spinner View Post
    Last but not least may be time for a water pump.
    Quote Originally Posted by jeff p View Post
    the 1st question is how old is the water pump impeller?
    they don't last forever. The sensor has been known to fail at times but my guess would be on the water pump just getting old.
    This motor has no dedicated water pump. Water for cooling purposes is being pushed through the power head by the drive impeller. Sport jet owner's don't have to concern themselves with little rubber impeller wheels. There is a 7.2 Stainless Steel impeller taking care of coolant matters.

    You might have some minor blockage somewhere in the system. I would try flushing it out real good and see what it does. It doesn't sound like your pressure is low enough to overheat but it is a hair low. I had mine plugged solid once and without flow it will overheat very quickly. My blockage was in a small hose that hooks to the lower part of the drive on the right side of the engine.

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    Member jeff p's Avatar
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    I didnt see where he had said it was a sport jet or had a jet lower on it? If it is a sport jet then no water pump, but if it is a jet lower then it should have a impeller in it for cooling
    Either way you need to ck water pressure at the sensor & if it is low the find out if you have a restriction or a bad pump. If it is good the we need to look at the sensor.

    oops I see you gave the water pressure readings & yes they are very low. If it is a jet lower put a water pump in it.

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    Member Crumm's Avatar
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    Quote Originally Posted by jeff p View Post
    I didnt see where he had said it was a sport jet or had a jet lower on it?
    It didn't but I know it is a Sportjet in a Jetcraft XS from his previous posts.

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    Thats cool, just shows the need for the poster to give complete info when asking for help.

    With that being the case confirm the lack of water pressure & start looking for the blockage.

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