Jumpy Tach

[RatFish]

Re: Jumpy Tach

The tach in my boat and truck resets to zero when I shut the engine off.

 

[cg2er410]

Re: Jumpy Tach

when i shut off my engine, the tach will stay at the rpm it was at when shut down. In theory, if tach connected correctly (according to teleflex paperwork) when you turn ignition key to on, the tach should reset to zero if calibrated correctly. then once engine started, go to correct rpm. Not sure if all tachs do this.

 

[Cool It]

Re: Jumpy Tach

Thanks for all the reply- My tach does reset to zero when I turn the key. I repaired the bad connector at the coil -But the tach is still jumpy Maybe I will replace -might wait for next season --enough money spent this season already!!<br /><br />Thanks<br />Cool It

 

[milkyway]

Re: Jumpy Tach

My rpm went from 4800, to 5000 then to 6000, and the high rpm was observed when moving towards wot. RPM stabilized at about 3000.It used to be 4700. Then I tightened the serpentine belt. I hit something 3 weeks ago that broke a tiny piece off the blade. I did not suspect a bad hub until both the salesman from boaters world and marine store told me to check the hub. With a new hub installed, I'm back to 4700 with 2 people and half tank of gas. Cruised for 4 hours, from 3500 to 4700 rpm, and everything went well.

 

[Cool It]

Re: Jumpy Tach

How do I know if my hub is no good????<br /><br />Cool It

 

[milkyway]

Re: Jumpy Tach

I am using the Hustler prop and hub. Engage the gear with engine off so it will lock up the propeller. Better remove the throttle cable so you don't't flood the carburetor (if you have this). With the propeller locked, use a big wrench and turn the propeller itself. If the propeller turns without causing the shaft to move, then the hub is not holding onto the propeller as it should as brand new. Another note you should know is if the hub turned because you hit somehting, it goes out of alignment. It usually moves up or down the throat. Buy a new hub and compare the exact position of the new hub from the old. If they are not exactly the same, even 1/4" off, guaranteed the old hub is bad.

 

[Cool It]

Re: Jumpy Tach

Thanks for the info -- I figured for $40.00 I would just go ahead and change the hub anyway. My present hub looks pretty old and beat up I did not change it when I put a new prop on. I dont know if this will help but I will test it on Sat , I only had time to change it today.If this does not do the trick then I will leave this problem until next season and try to enjoy the rest of this season-- I am still running pretty good at 3200 RPM and get a nice cruise!!<br /><br />Thanks<br />Cool IT

 

[milkyway]

Re: Jumpy Tach

Let me know how it goes. <br /><br />Your description that your rpm drops when going toward wot is "very strange". Mine went up and up to 6000 with a bad hub. This can also happen if your belt/s ( I have serpentine belt) are worn and all glazed.<br /><br />Buy the Sears engine analyzer ($49.99). It can read rpm to 12,000 I think. Just need to clip-on 2 wires and you will have accurate reading. Of course someone has to be watching it while you speed up and up and then compare with your tacho reading on dashboard. If analyser displays steady and reasonable rpm "with your experience on the throttle", I would replace the tacho outright than go crazy looking for something else. I tell you a lot of things come up after 5 years. I couldn't figure out why I was always reading 1/4 tank when the tank was full of gas. Checked all connections. Turned out the fuel sender was bad. I almost replaced the gauge by mistake. Cost me only $20 to replace and 1 hour of my time. I have 4 more projects to do.

 

[Cool It]

Re: Jumpy Tach

milkyway<br /><br /> Thanks for the info -- I replaced the hub and no change - I guess I wiil have to buy the analyzer. Maybe it is just a bad tach and IM going crazy here for no reason!!! <br /><br />I also replaced my fuel sender, easy job for this ametuer and all went well!!!<br /><br />Hope the weather turns around for the fall -I would like to be out there until the end of OCT.<br /><br />Thanks<br />Cool It

 

[milkyway]

Re: Jumpy Tach

Cool it,<br /><br />My dash tacho reads 1500 rpm on engine start and idle but the engine analyzer reads 650 rpm, which is perfect. I have decided to rely on the analyzer since if I lower the idle more, the engine starts to stall. So 650 rpm reading should be closer and accurate than the 1500 on the dash tacho. There are so many things about a boat that drive us all like crazy. My oil gauge sender is all corroded and needs replacement. Have to clean also the bilge. Just fixed the leak on the fuel line. I used the pipe sealer and now the engine compartment does not smell gas. Can't imagine how much I already saved by doing things myself. I still have to remove the manifold and see what's causing the temp to rise.<br /><br />This is my first boating year. When do people start to bubble wrap the boat for winter?