90 horsepower Johnson stalling

[Jasonfishing]

Hi fellow boaters, looking for some guidance / assistance with my 2000 90 horsepower Johnson j90plsse. Sorry to be long-winded, but want to give a full description. So I've had this boat and Motor since it was 2 years old, less than 120 hours on it. Put it in storage for many years. Pulled it out about 6 months ago empty the gas tank clean the gas tank and filled with new gas, all new fuel lines new primer bulb. New water separating fuel filter as well. Empty oil tank all new oil. Empty old oil lines. New spark plugs, carbs completely rebuilt. New thermostats as well and water pump. New lower unit oil. Took the boat out on two trips work exceptionally. At the end of the second trip pulling up to the doc engine stalled try to restart put in Gear engine stalled again luckily we were at the dock and just nudged back up to the ramp. Upon getting home opened it up to take a look and there was a little bit of oil in the air box. I clean that out and decided to take it out again the next day. Engine ran great the whole day no problems at all. Decided to take it out yesterday and had difficulty as soon as I put it in the water engine starts completely fine idles fine and will rev up no problem in neutral, but as soon as it's put in gear sounds like it's bogging down / stalling. I played around for about 15 minutes continuing to try and start it priming The Bulb Etc eventually went into gear took it for a nice run for about 15 or 20 minutes at 4200 RPMs wot is 5000 RPMs. Stopped for a couple minutes by an island put it in neutral leaving the engine running went to engage the throttle to run back to the ramp and again started to stall when in gear. After two tries it then went into gear with no problem and ran all the way back to the dock. I told into the dock and then as soon as starting to put in gear again began to die and stall. The idle is a little weak and I'm adjusting the idle screws today they were a little tight for what they should actually be. Other than that everything looks as it should. Engines getting gas spark on All 4 cylinders, just replace the spark plugs again today as I did run a heavy concentration of seafoam in the first tank of gas just to clean out any gunk in the engine and figured the plugs might be fouled, I did look at them a little bit they were a little black but nothing extremely out of the ordinary but opted to switch them out anyway Gap is correct. On another note, I noticed that the ignition kill switch doesn't seem to be working the boat will start up without the lanyard engaged and with the lanyard engage and then pulled off the boat does not shut off. However I don't think this has anything to do as normally that kills the Electric System right? This almost seems like it could be a fuel issue or an error issue but can't really figure it out any suggestions / assistance would be greatly appreciated trying to avoid a visit to a costly mechanic

 

[Bosunsmate]

You are correct about kill switch, you should fix that as well as horrific accidents have happened when those arent working
Sounds like an intermittent fault, they are hard to track down. You could test all your electrics to check they are in spec but your best bet is to test spark when its running poorly again

 

[ob]

If this engine was stored away for many years as you stated , I'd be shocked if the carburetors were not fouled. Personally, the first thing I'd do is remove dismantle and thoroughly clean the carburetor passages and orifices. Also perform a link and synch procedure and then go from there if your symptoms persist.

 

[racerone]

He stated that carburetors were " completely rebuilt " on this motor.-----Is the oil injection in service and have you verified proper operation of the oil injection ?----Post the results of a compression test.----Water pump impeller should be replaced as well.

 

[flyingscott]

When you replaced the oil lines did you bleed the oil system correctly? There is a specific procedure for that. Has the OIS sensor been serviced?

 

[oldboat1]

I’m with ob on the carb advice. If the motor was stored with any fuel in the carbs, there is varnish to be removed with a solvent. Would want to know more about cleaning and rebuilding technique. Shop rebuild?

 

[Jasonfishing]

Installed a completely new OEM water pump kit, pisses like hell. Carbs were completely rebuilt to OEM specs with OEM kits, I also replaced all the orifices and high-speed jets with OEM parts. I did not do anything special with the oil system. However like I said I have rented a couple times and it is consuming oil normally from the oil tank. Rebuilt them myself under the guidance of a technician I work with at my job. So I am a hundred percent confident carbs or not my issue. Update, took it out today and fired up fine at the doc but as soon as I put it in gear to go forward it bog down and stalled twice, restarted it gave it a little gas ran it for about 25 minutes and ran fine brought it down the idle shut it off restarted it and ran fine again. It really seems to be an intermittent concern

 

[oldboat1]

I don't know what the initial idle mixture setting is on that motor -- likely more than the typical 1 1/2 turns open on older motors -- maybe another lister can advise (think an oem manual would provide the info.). Guessing it may be upwards of 3 turns or so. Adjustment procedure would be the same as it has been for years. Get it started and warmed up at the correct initial setting, then tweak for best performance. In my experience, that's typically a little leaner than the initial setting, but your symptoms seem to say you may have them set a bit too lean.

 

[ob]

Besides the OEM kits you installed ,I'll assume that you either were able to visually inspect all carburetor passages or inserted a proper sized torch tip cleaning tool or small wire to clear all passages of any residual buildup. Past that it is critical that the carb linkage roller is aligned exactly with the scribe line of the fiber cam when in neutral and "just touching. The fuel pickup tube that resides near the bottom of each carb bowl is also a place that gathers residue that needs to be completely clear. If the engine was running good without the symptoms you are now experiencing when stored away then the fuel mix settings of each carburetor were at one time set correctly. Did you seat them clockwise lightly and count the exact turns they were set at when you disassembled the carbs to install the kits? If not ,then you'd have to start at so many turns out from lightly seated and proceed from their after the rebuild. If your stalling symptom when placing in gear cannot be adjusted out via the carburetor mix settings or being absolutely sure the carb passages have no obstructions,particularly the low speed circuits, then maybe you are in fact chasing an intermittent ignition issue.

 

[ob]

He stated that carburetors were " completely rebuilt " on this motor.

True ..but he made no mention of adjusting the all too critical link and synch procedure. Nor was there any mention of physically clearing all of the carb passages.

 

[Chris1956]

That motor likely has the SLOW system, where if the motor overheats, the ignition is partially killed leading to low RPM. Whereas your motor is not overheating, the fact that the killer lanyard is not working suggests to me trouble with the ign kill wiring, wiring harness diode or something similar. I would check the black/orange and tan wires for a short to ground, with the ign on. The harness diode is in the tan wire circuit. A wiring diagram would likely be helpful.

 

[Faztbullet]

He has the mechanical ignition switch,it supposed to turn key to off when lanyard is pulled not kill ignition. Sounds like the sync and link is off as the 60 degree are picky about this..

 

[Jasonfishing]

Carbs were completely taken off the boat, soaked overnight and new Jets put in, they were so clean I would lick them LOL in all honesty I really do not think there is an issue with the carbs they were like new, as I stated the boat has very minimal hours probably less than 120 or 150 so literally the carbs are like Factory new. I did adjust idle screws after a lot of research online it was stated that they should be about 6 and 1/2 turns out, I did have them at six and a half turns out which seems like a lot but after further research is normal for these type of carbs on this motor. However when I did have them at six and a half the idle was a little low so I set them out to eight 1/2 and she purse fine at idle. I'm kind of thinking maybe it could be the kill switch not sure. Although this is the original Killswitch I know something's wrong with it but it's always as soon as you put it in gear if you have it off. I suppose I should replace that but I really don't think that's my issue as the boat works perfectly other than the intermittent stalling when putting it into gear forward or reverse. She's gassed up charged up and ready to go now taking some friends out we'll see what happens. Thank God for free on Water towing assistance LOL. Haven't had to use it yet but you'll never know. Thank you for all the feedback all excellent points and things I'm still looking into with any luck the changing of the spark plugs might have done it as I did take it out yesterday and it stalled once when I put it in the water but that's kind of normal for a two-stroke will see what happens today. Only thing I can think is the plugs might have been a little fouled as I ran a lot of seafoam through it the first couple times I took it out as the engines been sitting so long I wanted to make sure everything was lubricated and clean, so I just opted to throw out the old plugs and put new ones in and they work pretty black and a little oily for such little use

 

[Bosunsmate]

good luck and lucky you get towing assistance, i just end up risking being blown into the south pacific if things go wrong for me.
Do do a closer inspection on plug colour if it does run poorly.
May just be settling in as you say after the seafoam, and mine runs poorly until shes warmed up

 

[zenwriter]

I had the same engine...the manual states idle should be adjusted on the water in forward gear, one carb at a time. Mine worked best at 6 turns out...

Another thing to look at is fuel supply. I had an intermittent issue caused by air leaking into the line at the fuel tank. Running off an aux tank could test your supply.

 

[Ric Flair]

For what its worth. I have a 2003 Johnson 90. I had some weird symptoms with sudden power loss or sudden "missing" too. Noticed my key switch (kill switch lanyard) was no longer operable, nor was the push to choke portion of the switch working correctly. Replaced the key switch (with factory parts) and problems have went away. I believe the "kill" portion of the key switch was intermittent.