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 couldn't easily find it but Google says the location is on the blower drive pulley