90 johnson 115hp

[swick73]

just rebuilt the powerhead and trying to figure out idle rpm....now it will barely idle in water and once in gear it dies. any ideas and where is the idle adjustment?......since this is orfice carbs..

 

[Joe Reeves]

Re: 90 johnson 115hp

There is no idle adjustment other than a mechanical idle stop. Hopefully you have all the jets in their proper locations.

If you have proper compression and spark, the idle on a flushette should be:

For 1 20" shaft engine: 1000 rpm

For a 25" shaft engine: 1200 rpm

In the water, the idle will drop to its normal idle rpm.

Make sure that the throttle buterfly linkage between the carburetors are adjusted properly...... butterflies open and close at the same time.... AND at idle both are absolutely closed.

Also make sure that the cam roller is adjusted properly..... the throttle butterflies just start to open when the scribe mark on the cam is dead center with the cam roller.

 

[wilde1j]

Re: 90 johnson 115hp

Agree ^^^ plus ... Did you analyze why it failed? May have been due to lean running due to crap in the carbs. Were they rebuilt along with the PH? If not, that might be a place to start. In any case, if you just repaired w/o determining why, it WILL fail again.

 

[swick73]

Re: 90 johnson 115hp

Thanks for the info....i rebuilt it for low compression on one cylinder and come to find out it had frozen rings that broke and scored the cylinder wall. had two bored over and two resurfaced....went through the carbs and they were pretty clean and in good shape...im checking into the tach working of and on as well....this has turned into a headache..........lol

 

[Joe Reeves]

Re: 90 johnson 115hp

I'm assuming that your statement of "im checking into the tach working of and on as well" contains a typo and was intended to be typed as "im checking into the tach working off (OFF) and on as well."

If so, do the following test.

(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.

 

[swick73]

Re: 90 johnson 115hp

Thanks for the info ur a great help and its truly appreciated......i beleive my stator is shot its not charging........will this have an affect on the timinig? im mostly haveing the issue of idling and once in gear it dies. I have the seloc manual and its not to clear on setting the timing....does this engine idle off of timing?

 

[Joe Reeves]

Re: 90 johnson 115hp

The engine is timed by the flywheel key. The key keeps the flywheel sensoring magnets aligned with the crankshaft. As long as this key isn't sheared, the engine is in time.

Idle has to do with synchronization as mentioned in my first post (cam roller) and the mechanical idle stop. When the stator is providing proper spark, we can go into the idle problem if it still exists.

 

[swick73]

Re: 90 johnson 115hp

Well took it out today and set the timing and wahlah....how it got that far off timing ill never know.....now it purrs and put it in gear and just putts along....now off to finding a new stator to keep my battery charged.