Gauge goes crazy

[Bryce C]

My RPM gauge gets weird when I turn the water pump on. It works perfect when the tm is running at low, medium, or high. But when I turn the main water pump on the gauge maxes out and no longer reads the rpms of the machine.

 

[Dwain Ray]

My RPM gauge gets weird when I turn the water pump on. It works perfect when the tm is running at low, medium, or high. But when I turn the main water pump on the gauge maxes out and no longer reads the rpms of the machine.

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When you say waterpump and main water pump you loose me. I have no idea what your talking about. Transfer/ supply/auxiliary supply pump??? Those terms would make me think that you carry water and is supplied to the machine by this pump . Where as ,main/pressure/ high pressure or name ie:cat/general/ hipro would make me assume that you're talking about the pump that supplies soulition to your wand . Then there's the wastepump i dont know what else you can call that one but waterpump pump and main pump can be interpreted differently . But with that said i don't know about your machine specifically but generally speaking the tachometer has a magnetic pickup and so machines mount this pickup on the main pressure pump and attaches a magnet on the back ( pump side) of the clutch pulley that pulley generally speaking again , turns much slower than engine or blower and is compensated electronically with a setting button on the tach. Perhaps with the work you have recently been doing in that general area youve inadvertently knocked this outa whack . I tack my machine off the driveshaft and measure blower speed below is a picture of mine yours will probably look different but worhs the same ill try to find another picture and edit with it