Mercury Loss of Tach & Starter

kingfish62 · #1 June 18th, 2007, 09:12 AM

Good morning fellow boaters,
I trust all had a great Fathers day weekend out on the water. Mine brought me a new problem that I hope some of you may be able to shed some light on. I headed out on the water yesterday and my 1990 3cyl 90hp engine (ser#OC190284) started and was running along just fine. I looked down and noticed that my Tach was frozen at about 1200 rpm. I slowed to idle speed and shut the engine down in an attempt to reset the Tach. The starter did not engage, click, sputter or otherwise do anything remotely resembling starting the engine. The good news is that I cary a rope starter and the engine fired right up and we continued boating. The bad news is that the problem still exists. I know that there is a common link between the Tach freezing up and the starter doing absolutely nothing I just don't know what it is? Any help is appreciated as I am no mechanic... Thanks

rickdb1boat · #2 June 18th, 2007, 09:27 AM

First thing I would do is have the battery checked. The Tach. relies on a signal from the charging system in order to operate. Your battery may have an internal short...

kingfish62 · #3 June 18th, 2007, 09:51 AM

Thanks for the reply. The batteries were fully charged when I started the boat. They live in 1.5 amp maintainers and are only appx 2months old they are Sea Volt 675 Marine cranking amp. and I have two on switch unit. I was operating in the both battery position. Assuming I find the batteries to be in good shap and I suspect I will what components do the Tach and starter have in common. I.E. Voltage Reg., Rectifier, Power Pac??? Again I am clueless but have looked tru many threads here and see that these components can affect the Tach however I don't know if there is a common link to starter. Again it doesn't click, spin, or move as if no power whatsoever is getting sent to it.

Chris1956 · #4 June 18th, 2007, 10:06 AM

King, If the motor will not crank, then you are not getting voltage to the starter solenoid, starter or both. The charging system is mostly seperate from the starting system. First check is battery terminals, and where the motor battery cables connect to the battery switch. Second is voltage at the starter solenoid. Jumper the starter solenoid from +12V side of secondary (large battery cable) to plus side of primary (small wire, usually yellow), and see if solenoid clicks and starter spins. If so, your ignition switch or wiring to the switch is bad.

Get the starting system fixed first. Then start trouble shooting the charging and tach.

kingfish62 · #5 June 18th, 2007, 10:40 AM

Thanks Chris, I will try these things this afternoon after work. Assuming all checks out what else would I look for? Keep in mind engine started fine and then I noticed I lost Tach. I manually shut down and then had no starter. I have not realy begun to trouble shoot the issue so all thought are welcome and the more to look at may lead to a fix wothout more posting in between. Do you know if I suspect the starter solenoid, can I switch one of the trim & tilt solenoids for verification? They look the same.

hkeiner · #6 June 18th, 2007, 01:00 PM

The following FAQ might be of help. It outlines a systematic method to diagnose starting problems using a voltmeter/ohmeter (multimeter) to see if a circuit is incomplete, if voltage is insufficient, or if the starter itself has failed. It has helped me in the past and I think it is a great FAQ.

http://forums.iboats.com/showthread.php?t=158071

kingfish62 · #7 June 18th, 2007, 02:04 PM

Again many thanks for the help. I have printed the FAQ sheet and will use it later today to assist in trouble shooting. To verify the solenoid if it measures wrong can I take one from the trim side to use in trouble shootin? They appear to be the same and according to the drawings they have the same PN. Keep the ideas coming I will try them all until I get things up and running and let you all know the outcome.. Thanks again to those who have already submitted ideas and in advance for those to follow.

kingfish62 · #8 June 19th, 2007, 09:03 AM

Thanks Chris for your sound advice. I got home yesterday and jumpered the Solenoid and the Engine turned over just fine. The wiring checks good to the switch so my plan is to replace the ignition switch today. Thanks for all...

kingfish62 · #9 June 19th, 2007, 09:09 AM

I didn't mean to leave anyone out when I was thanking Chris, my apologies... Thank you, to all of you who provided advice on this problem. I will post once more tomorrow just to validate that the new ignition switch was the total fix. My confidence is high that it is. Again thanks!!

Silvertip · #10 June 19th, 2007, 02:02 PM

There is a main fuse on the starboard side of the engine. If it's blown, you lose the starter and it also fails to feed the harness to the controls and hence the tach. Since this fuse is probably blown, the next question you will have is what caused it. The answer is virtually anything that draws its source of power through the engine harness. DO NOT replace the fuse with a larger one or the wiring will become the fuse.

kingfish62 · #11 June 20th, 2007, 10:33 AM

Thanks for the information in reference to the main fuse. A local buddy of mine also told me about it yesterday. After he told me I went and took a look at it. The wire to the inline fuse holder had corroded and broken. The fuse itself was actually good. I put a new water-resistant fuse holder inline and the problem is solved. Turns out the Ignition switch was good all along so I will be returning the one I bought on my way home yesterday. I am going to exchange it for a manual for my engine. Again many Thanks to all who replied and assisted with the troubleshooting of this issue. I'm sure I'll have other issues in the future that I don't look forward to however, it is nice to know that the help is available here at Iboats. Safe Boating to all!!!!