Speedometer issue

[Fromtoronto]

I have a 3.0 ltr Mercruiser on a 2009 Q4 Tahoe.

My speedometer is at about 40 mph when still, it moves up when running . Obviously have cleared the hole for debris which usually stops it from moving at all. So why is its baseline now at 40mph? I am not sure if I go 20mph it goes to 60, .Otherwise I may be able to dial it back to zero.


I have been using GPS latley for speed but would be nice to have.

If your aware, thanks, pictures always helpful.

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[Trooper583]

Re: Speedometer issue

I battled my speedo tube for about 6 months last year. I am assuming that you are running an alpha gen 2? On my boat I had to go to great lengths to make sure that my hose wasn't kinked our pinched anywhere. That might be causing your probelm. I have removed the tube from the back of the gauge and blown some low pressure air back through the line to make sure that small debris hadn't migrated up the tube. (have someone stand at the drive and feel/listen for the air). Just make sure its low pressure. Have you had any outdrive work done lately? It seems people have a lot of problems after having work done. (mechanics get in a hurry sometimes) Other than that, it might be a gauge problem.

I have a 3.0 ltr Mercruiser on a 2009 Q4 Tahoe.

My speedometer is at about 40 mph when still, it moves up when running . Obviously have cleared the hole for debris which usually stops it from moving at all. So why is its baseline now at 40mph? I am not sure if I go 20mph it goes to 60, .Otherwise I may be able to dial it back to zero.


I have been using GPS latley for speed but would be nice to have.

If your aware, thanks, pictures always helpful.

​