I have just purchased a 1994 procraft with 150 hp Mariner Mag iii. The tach reads 1000rpm with the engine off and bounces all over the scale when the engine is running. It reads 4000 rpm at engine idle. Without going to a lot of trouble, would a bad tach be a good guess? I have tried the zero adjustment and it doesn't change the 1000 rpm reading with the engine off. Haven't checked the rectifiers yet. Also, the speedo doesn't work. I have disconnected the tubing where it goes into the foot and blew compressed air in. It is totally stopped up. the pitot hole was plugged but I opened it up with a wire. Air will not go either way. Putting air in the tubing to the gauge causes the speedo to read. Is there some way to check the part of the tubing and pitot in the foot without dropping the foot itself? Could I add a hull-mounted speedo foot and by-pass the motor pitot? Thanks for your help!
