98 200hp No Techometer reading at lower speed.

[R1racer]

Hi ..Its a 98 200 HP , Took it out today for fishing trip , It started OK ,At the dock i did not pay much attention to the Tech reading , It usually turn950-1000RPM at neutral . Got it on plain and reached 4000RPM. . On the way the Fish finder flashed High voltage detected and the finder shut down . I restated it but it did the same thing ( which could be a coincidental??? ) , i start slowing down and noticed my Tech was jumping all over till i Start trolling and notice at lower speed no tech reading what soever, When i get it back on Plain the tech works at high speed also if i slow down a little tech droop to Zero . Eng is running 100% and not skipping a beat . Went home and hocked the hose ..I usually see 1100 RPM on land but today i see Nothing ...?

• 
  
  I checked my panel wiring all looks connected . My fish finder receive it's voltage from the 12V Aux at the panel
  I have fully charged 2 marine battery
  Am reading 13v at each battery when Eng running . when i increase RPM's to my guess 1200-1250 i see 13V
  
  I have the Factory OMC manual ..

Any ideas ..i ran out of day light to do Tachometer test which the manual instruct to do. I did read something about the rectifier/ regulator could cause Tech to act up

 

[Faztbullet]

Re: 98 200hp No Techometer reading at lower speed.

Check the rect/reg and connections under pack

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

In there any way i can bench test the Techometer it self ? Or

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

OMC factory manual Tachometer /rectifier test instruction instructed to do the following

With key on and eng not in the run position in running position check the V between the purple and Black wire that comes to the back of the tachometer at the panel ,you should have the battery voltage ..Which i got 12.74

With key set to the ON position and Eng not running Then check voltage between the black and Gray at the same harness which is the one at the tech i should see Voltage there , If voltage detected pull the gray wire from the Eng side which comes from the Rectifier if Voltage goes away immediately then replace bad rectifier /regulator........ which i lost voltage when i did that step . So am confident that i got bad rectifier/regulator

 

[Georgesalmon]

Re: 98 200hp No Techometer reading at lower speed.

You said you had 13v at the battery with the engine running? Seems like it should be lower if a bad rect/reg. Than again seems it should be higher with a good rect/reg. With the engine NOT running there would not be any voltage on the gray wire. the gray wire from the stator is an ac voltage to drive the tach. do you have ac voltage on the gray wire with the engine running?

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

With the Eng not running i had 12.72 DCV on Bat #1 & 12.77 On the 2nd , When i ran Eng Sunday after i noticed tech not working just to do do a quick health check on the battery i was reading around 13.2 DC V @1000-1100RPM which is a good indication that my charging output getting to the battery somehow

However Yesterday i did the required test by the book which doesn't require Eng to run at all , I got 12.72DCv=Supplied battery Voltage with key on between the purple and black from the harness that connect to the back of the Tech at the panel , The 2nd step which to check between the Gray at the same harness & the black i did read lower voltage than Battery voltage .So as instructed i disconnected the gray lead at the motor/rectifier and lost the DC voltage that lead goes to the rectifier . at this point the manual calling for rectifier replacement since i lost the voltage at the meter ???!

 

[Georgesalmon]

Re: 98 200hp No Techometer reading at lower speed.

Well, I'm no expert. I just remember that the tach signal (gray) comes from the stator and is an AC voltage derived by the magnets going by the stator coils. I just don't undertsand why you should read voltage if the flywheel is not turning. It seems to me that if your battery is 13.2 with the engine running and less when stopped then your rect/reg is working, or at least sort of working. The stator wires are usually yellow. If you disconnect those wires from the rect and ran the engine you should find some AC voltage present. The gray tach signal wire should be attached to one of those yellow wires at the rect and sends the AC signal to the tach. Can you check for continuity from the gray wire to the tach? I think I'm getting in to deep with my limited knowledge. Best if you wait for sombody else to help. Sorry

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

The test you referring to is with the boat running to 4500 RPM to detect AC voltage at the gray lead , as I mentioned i detected a message displayed on my Fish finder stating ( High Voltage detected) then Tech stopped working , My guess its a good indication that Rectifier went open but it's a guess ...

 

[Joe Reeves]

Re: 98 200hp No Techometer reading at lower speed.

In there any way i can bench test the Techometer it self ? Or

(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Remove that gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

Joe ..Thank you so much for all this great info . My Tech appears to ONLY function at high RPM's so when i get on Plain tech go all the way up but nothing at low RPM's say if am trolling or docked it doesn't register any RPM at all. I received a High Voltage detected at the fish finder screen when i noticed it quit working.

I looked at my manual diagram and noticed there is no Terminal strip all wires are connected with factory butt connectors & plugs .

If i understood your instruction correctly and Lets say am going to run a jumper or splice it in , Am i going to take the Gray wire coming from the Tech and jump it /splice Directly to the Yellow/gay or Yellow coming from the stator ?????

Please note i have 2 yellow wires coming from stator , One is Yellow /Gray and one solid Yellow

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

Joe

Lets say am going to run a jumper or splice according to your above test instruction , Am i going to run My Gray Tech wire directly to the stator Yellow wire ???? Which yellow i should go with ????

 

[Joe Reeves]

Re: 98 200hp No Techometer reading at lower speed.

Lets say am going to run a jumper or splice according to your above test instruction , Am i going to run My Gray Tech wire directly to the stator Yellow wire ???? Which yellow i should go with ????

Use the Yellow/Gray. If that doesn't give the proper results, then try the plain Yellow.

 

[R1racer]

Re: 98 200hp No Techometer reading at lower speed.

Joe

Lets say am going to run a jumper or splice according to your above test instruction , Am i going to run My Gray Tech wire directly to the stator Yellow wire ???? Which yellow i should go with ????

Use the Yellow/Gray. If that doesn't give the proper results, then try the plain Yellow.

I think i found the Problem ...Went down to the local marine repair shop/friend pulled a good Spare Tachometer just like the one on the boat , connected it and started the boat , Still no Tech reading !!!