Tach problem

[dymo]

I have a 70HP Chrysler and I had to replace the tach. I bought a Teleflex Tach with my motor listed. With the ignition off, the needle will sit anywhere from 200 - 400rpm's (says needle can sit anywhere when off). When I turn the ignition on, the needle goes to zero. When I turn the motor over, it will fast idle at about 1000 rpm's and normal idle at about 650 - 700 rpm's. So far so good!!!<br /><br />Now when I throttle up, the tach will not indicate over 1800 rpm's at WOT. I can only guess that my boat is going about 25mph. The instructions indicate that the setting on the rear of the tach should be pointed at 6P and that's where it is.<br /><br />I'm new to boating so I can't tell you what 1800 or 4500 rpm's sounds like on a 70hp outboard. The motor doesn't sound like it's racing high and it runs very smooth. I can't imagine that a boat weighing around 2000lbs would go 25 mph at only 1800rpm's.<br /><br />Any help or suggestions would be much appreciated.<br /><br />Thanks for your time,<br /><br />Dymo

 

[dymo]

Re: Tach problem

*Bump*

 

[dymo]

Re: Tach problem

*Bump*

 

[suzukidave]

Re: Tach problem

Dymo, <br />if you are on plane you are doing well over 1800 rpm. The problem is in your tach or your motor electronics ( sometimes a tach issue will tell you you have a rectifier or stator problem).<br /><br />Teleflex has a web page with a lengthy set of technical bulletins. Chryslers have unusual alternators (many poles) that affect tachs so I would take a look for anything that might help there first. If not, you need to try a different a tach on the boat to isolate whether it's the tach or your electronics. If it's electronics, then troubleshooting is outside my knowledge beyond checking the wire connections. Go back in history on this site for posts with Admiral "Schematic" in them (not starting them) that deal with rectifier problems. He has posted tests for troubleshooting the system.<br /><br />good luck

 

[Bry21317]

Re: Tach problem

My Force Engine also has a 20 Pole alternator and it was a pain to find a tach that would work for this. Your chrysler may have the same type of alternator. Teleflex didn't have one that I could find at the time, so I found a company called www.beade.com and they got me one that works awesome. <br /><br />Find out how many Poles your alternator has and then go from there.<br /><br />Hope this helps.<br /><br />Thanks,<br />Bryan Cox

 

[Bob_VT]

Re: Tach problem

Teleflex website for trouble shooting tachs is:<br /><br /> http://www.tflx.com/PDF/99320.pdf <br /><br />Hope it helps.<br /><br />Bob

 

[dymo]

Re: Tach problem

Thanks alot for your replies. I have found that the stator seems to be fine but the rectifier seems to be out to lunch. The stator is also a 12 pole. I did all the tests as indicated in the manual and I don't get continuity between connections from any of the tests as the manual says I should.<br /><br />I'll start with the rectifier and see what transpires from there.<br /><br />The bizarre thing is that the battery is charging at 13 - 13.5 volts while underway. I'll let you know the outcome. <br /><br />Thanks again,<br /><br />Dymo