Disappointing First Outing

[Vandalizer]

I finally ( ) got her out yesterday morning. Everything went smoothly up until it fired, when I noticed my tach was not working. I did r/r it when I was cleaning up wiring/rigging, but I was damn sure it was wired back up correctly. So I'm worried at this point that I fried something, and pissed because I can't see my engine speed. So I take her out and she's a little hesitant at first (plugs loaded, I'm sure) but eventually steps out just fine, and seems to wind all the way up (sounds like 5700-5800 to my ears) even though I went down 1/4" on the jackplate. Make a few runs, and the most I see is 61.
Second issue- I wasn't able to stay full throttle as long as I wanted because my hyd steering was a bit sloppy- I meant to re-purge the helm/cylinder, but just ran out of time. So hopefully I just have some bubbles in there.
After a few passes when I stop, I noticed that the rod that runs across the mid to act as a trim stop is way out on the starboard side- I try to put it back in the guide hole, and the swivel pin on the end falls off. So the rod goes in the boat. I'm thinking I'll just thread the end and use a nylock nut.

So the end result was three issues to fix, and a slower speed by 2mph with seemingly the same engine speed. I need to get the tach back working so I can really figure out what's going on.

On the bright side, at least I got it out again.

 

[Gimme Fuel]

You will get her figured out.......at least you are on the water. Its the little issues that cause the biggest headaches.

 

[groundloop]

If you check the tach wiring and find that it's ok the next thing to look at will be the rectifier.

Good luck.

 

[Vandalizer]

One thing that I forgot to mention was something strange the tach was doing- at anything other than WOT, it was pegged at 2k. When I went to WOT, it would then jump to 6k.
There are only three wires on the tach- +12V through the key switch, GND, and the signal wire. This would seem to indicate to me that the +12 and GND wires are ok and something strange is happening on the signal wire.
If it was a rectifier issue, would I have expected something amiss with the engine? Definitely seemed to be charging the battery OK too.

Any help appreciated, I won't be able to get out to look at it until late tomorrow at the earliest, recovering from a minor surgery.

 

[illMATTic]

If I remember correctly, the rectifier just converts your ac to dc. The tac signal is taken directly from the stator.

The tac may be sticking until it gets more voltage to make it jump up to where it needs to be.

 

[Vandalizer]

Thanks Matt- the fact that it's on an outboard motor apparently made me ignore the stuff I know about electronics- makes perfect sense.
As soon as I can borrow a multimeter I can figure this out.

The two things that are confusing me here are that it definitely seemed to charge while I was out there (cranked a little slower the first time, and I had already fired it on the hose once this year - I could verify that with a multimeter as well) and the ignition was obviously working, and since mine is electronic it's fed from the stator. Those two facts would seem to rule out both the rectifier and stator and point to a wiring mistake, no?

 

[Mpowered5]

If I remember correctly, the rectifier just converts your ac to dc. The tac signal is taken directly from the stator.

The tac may be sticking until it gets more voltage to make it jump up to where it needs to be.

The tach signal originates from the voltage regulator/rectifier Most likely that is bad. My merc 115 sat for a year and the regulator went bad in it. You wont notice the battery not charging unless your running something like a radio the motor will run fine with a bad rectifier mine did. check the engine manual you can use a multimeter to check the resistiance of the rectifier make sure you disconnect the battery first tho!

any other questions let me I just went through this issue myself.

 

[speegt]

tach

i had some similiar problems with a tach , i switched tachs and the problem was solved just my experience . good luck

 

[merc245]

I always changed out the rectifier when my tach went south. My mechanic told me why I was burning thru so many rectifiers, I was running while playing my 400 watt stereo system,working the jack plate and trimming all at the same time and that was just to much for the 16 amp charging system!And sometimes doing it with the nav lights too and with eye closed!

 

[illMATTic]

The brown sig wire for the tac is only pulled from one of the two yellow wires coming from the stator. There is nothing passing through the rectifier to get to the tac. Usually the tac will start bouncing when the rectifier goes bad. Not sure if it will cause your symptoms.

 

[Vandalizer]

Thanks for the help- I was able to verify good wiring from the tach to recrifier' and he diodes appear to be ok too. The only thing I could find (and I found his before checking wiring) was that the wiring harness was a little loose at the plug inside the cowling. Haven't had a chance to pull her out of the garage again to double check, but may be able to tomorrow. I'll definitely keep my fingers crossed that was the problem, but I don't know how that happened.

 

[Vandalizer]

Tach is alive and well- must have been the slightly loose wiring harness, although everything else worked fine.
Had it out yesterday for probably 2-2.5 hours running at or near wide open the whole time. Finally saw 63 again @ 5650, but it was a bear getting there. There was a good solid wind kicking up some good waves, some even turning into (just barely) white caps. I really need to get up to the river so I can get more than half a mile stretches to run wide open in, I think I can wind her up a little more... hopefully 65 is still a possibility.

The real surprise of the day was that I ran a total of 38 miles on somewhere very near 8 gallons. I wouldn't have believed it without the GPS tracker I was using, that got reset when I put in. Eat that EFI motors!!