'89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

I have been reading some posts looking for an answer to the problem that I am having, and I'm hoping for some good advice to resolve the problem. I purchased the boat with this problem and have had it working one time for a couple of days then it went back to the same issue.

The motor will start and run great at idle. It will even Rev snappy to 3k RPM, but once u try to pass 3k RPM it will start to surge as if the motor is starving for fuel. It is also smoking a little excessive, but I'm sure thats probably due to the fact the original owner use to drive the boat around no more than 3k just to use the boat since it wouldn't accelerate. When I had it working for two days, I removed the fuel pump and cleaned it. There is a one way flapper valve built into the plastic housing that never seemed to get clear. I put the pump back together and the motor would rev to 4,500 (I wouldn't want to rev anymore out of the lake other than very short burst). This worked two days, then the problem started happening just when I was going to take it to the lake to test it. I took the pump back apart and found the one way flapper valve hard to blow air through one minute and easy to blow air through the next. I wanted to purchase another side housing but I couldn't find a replacement part so I bought another VRO2 pump to be sure. After resolving the carbs overflowing due to fuel pressure, the motor will start very quickly and idle very smooth and even rev smoothly at 3k RPM. The problem is going past that. I have cleaned the carbs, replaced the tiny vaccuum lines with the same, replaced all the fuel line, replaced the primer bulb (Which gets hard), and gapped all the plugs. I DID notice some electronic goo under the flywheel. Would a Bad Stator cause this sort of problem to happen? I can see that the Timer Base assembly has been replaced with a new one, but the stator looks to be the cause for the leaking goo. I have not checked for charging as of yet. I was starting to think the top seals could be causing a lack of gas in the top two cylinders possibly causing a surge?? I checked the plugs, and they are black with carbon deposits, esp since it is smoking a bit. Would the seals cause this?? The Goo from under the flywheel, or is there a fuel problem that could cause this?? Please assist, I would very much appreciate some professional opinions.

Just some general information, I get 90 on all cylinders except port side top cylinder, and it gets 80psi. I use to do outboard repairs on older outboards with my dad, but never worked on this year model Johnson before. I have done extensive mechanical work as well as carpentry work. I'm good with my hands. Any information would be appreciated.

Thank you very much..

Brent..

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

It sounds like the stator is bad or in the process of going bad. Check the spark on each cylinder. It should be able to jump a 7/16" gap.

I'm not sure that is your problem, because with weak spark, you usually have a very hard time starting a cold engine. Once it starts and warms up, it usually restarts easily and runs better. Having said that, If you have weak spark, you need to fix that, as it's certainly not helping.

It could just be something as simple as doing the link and sync adjustment and checking or setting the timing cam adjustment.

Black sooty plugs usually indicate a rich fuel condition. When you rebuilt the carbs, did you happen to replace the bowls on any of the carbs. If so, you needed to remove the main jets from the old bowls and put them in the new ones. Seeing as it had this problem before you bought the boat it might be worth a look. Someone else may have forgotten to do this. It will cause the exact problem you describe. When the engine transitions to the high speed jets the unmetered fuel is sucked into the carbs that don't have the high speed jets in place causing a rich condition. You don't want to run it like that for long, as the excess fuel will wash the cylinder and you will damage the piston and/or the cylinder from lack of lubrication.

If nobody has said it yet, get a factory repair manual. It will make your life so much easier. You can find a used one on Ebay for cheap. Read my thread on how to make sure your ordering the correct manual for your model year.

Top port cylinder is a little low compared to the others, but not bad.

The surging could be caused by intermittent spark on one or more cylinders.

I have no explaination for why it ran better for a short while.

I am not a professional outboard mechanic, so take it for what it's worth.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

I wouldn't recommend revving the engine beyond 1500 to 2000 rpms if it's not under load. Are your running tests on the trailer, or when the boat is in the lake? That V6 will seem to run just fine on the trailer with only 3 or 4 cyls firing. You need all 6 firing when the prop is buried 1 1/2 feet under water. From your comments, I'd be inclined to check the voltage output on the stator. When cranking, ouptut should be at least 200 volts, as measured with a special "peak reading" voltmeter. Plugs are dark after idling. They become light tan when running at WOT.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

"I'm not sure that is your problem, because with weak spark, you usually have a very hard time starting a cold engine. Once it starts and warms up, it usually restarts easily and runs better. Having said that, If you have weak spark, you need to fix that, as it's certainly not helping."

That almost describes how its running perfectly! It does take a little bit of cranking to get it started and running. Though after replacing the fuel pump it has gotten better, it will idle with very little high speed throttle input now. But compared to after it is warm, there is no comparison. When warm the starter will barely spin and its running, cold you have to crank it a bit. I thought that was just a 2 stroke nature. I have not checked to see if the spark is missing on any cylinders or irratic. I will have to do that asap. Right now its raining and nasty, can't do it now.

I have been running the test on the trailer. I have not had the chance to put it on the water, but I already know its not gonna run right thats why I have been trying to fix it on land first. Do I need to lake test it for better diagnosis? I have noticed that on a couple of the coils the black insulation on the back has exposed a metal connector that goes to the powerpack to tell the coil when to fire. I didn't think by that being exposed it would be a faulty coil, but who knows. I will have to test the ignition. This motor has been well taken care of besides a little neglegence. It is very clean!

You mentioned float bowls. I did not replace a float bowl yet ,but I was thinking about replacing the top bowl because the fuel inlet nipple keeps coming out. It looks like a O-ring gasket goes on that nipple but mine is missing it so fuel was seeping out the sides of it. That would cause a fuel flow problem and a vaccuum leak. So I used epoxy and locked the nipple in place, leak fixed. Not sure how long it will last, so may end up buying another float bowl, and I'm GLAD to hear the advice. I will look for a factory manual, what am I looking to spend 30 bux? I have a manual for the "Johnson motors between 48-200hp" those manual suck! I have hated manuals like that for years, but factory manuals are EXPENSIVE! Ugh!

I noticed no one mentioned anything about the top or bottom seals, so I guess that would mean after all other options have failed, maybe its the seals no? Is that not a common thing to go wrong with Johnson outboards after being in service for years? My '77 Merc 850 had a leaking top seal from the time I got it to now.. I never fixed it cuz I would have to split the case to remove it.. It still runs like a champ, so a little gas leaking won't bother me! Heheh

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

These two stroke engines can be a little hard to start when cold, especially if you don't follow the proper start procedure. If you have weak spark it it will be REALLY hard to start.

I've used my inductive timing light to do a quick check to see if all cylinders are firing. If you have one, it's a quick and easy way to check for no spark or intermittent spark. It will not tell you the quality of the spark. You need a spark tester for that.

If you look in ebay motors, you should be able to find a used OMC manual for your model and year for between $25 and $35 shipped. I just bought two and they were both under $35 with shipping. Be sure your ordering the correct manual. Go by the part number not the year on the front cover.

Coils don't fail that often. Each coil has a metal strap that grounds it to the engine block. Over time you can get a poor connection. Removing and cleaning usually resolves that problem. If you suspect a bad coil swap locations with a good one. If the problem moves to the other cylinder it's bad.

They run good on the muffs because there is no exhaust back pressure with the engine out of the water. The real test is in the water.

If your certain you have good spark on all the cylinders and one or two of the plugs are black and sooty, you need to find out why those cylinders are getting too much gas.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Greg's right-an inductive timing light is a helpful tool, when testing for spark when the engine is running. The flashes from the gun will tell you a lot about the quality of spark on each plugwire: misses, no fires, weak firing, etc. Your engine should have the factory plastic fuel bowls. Over time they warp and won't make perfect contact with the underside of the upper carb body. They all warp over time-usually the biggest problem is fuel leaks at the mating surface. That thick, rubber gasket just won't take up the slack. It is also possible that if warped in the right spot, the engine can run lean. You may want to replace them with the older style aluminum ones. The factory made a special bowl replacement kit at one time due to all the problems with the plastic bowls.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

It has been a little since I have been able to diagnose anything on the motor. Allergies are NOT friendly to me this time of the year and it has made it very hard for me to do anything outside lately. Sucks!!!

I finally got the timing light on the outboard and what I have found is very interesting. First of all, Greg E it is starting Excellent cold. You just have to tap the choke a few times to keep it running for the first few seconds and then it will high idle on its own and smoothly. All the cylinders are firing at idle, and the motor is running VERY well at idle. When you Rev the engine just past 3k ALL the cylinders stop firing. You get big blank sections on the timing light where there is no fire or very little/intermitting fire on all the plug wires. Could this be the stator/pickup assembly underneath the flywheel??? Or is that a power pac??? Thats the question. The timer base assembly is new, so I counted that out. If I was a guessing man, I would say I have a bad power pack. It started raining so I had to stop diagnosing. Just my luck, need to finish my garage. So what do you guys think??

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

I've seen that happen, and I am not sure that it isn't caused by the timing lights inability to keep up at higher RPM's. I just don't know that answer. Does it really sound like its missing on all the cylinders at higher RPMs?
Also, running at 3000 RPM's with no load isn't the best thing for the engine. If your going to do that bring the rpms up and back down slowly.
In your first post you mentioned that it looked like the stator had leaked some goo on top of the engine. That's a sign that it's failing or has failed. You need to check that and confirm that it's either good or bad.
I think it's time to invest in a DVA adapter and a multimeter if you don't already have one, so you can fully test the outputs from the power pack stator and timer base. Youtube has a decent video on how to test the power pack outputs on a 225 Evinrude. There is also a video on how to build a DVA adapter if you don't want to buy one, but they aren't that expensive.
A bad stator would not explain the two sooty plugs, because all the cylinders would be affected or at least one bank. I'm not sure you don't also have a fuel problem. Verify the spark is good and then move to the fuel if the problem isn't resolved. CDI has a great outboard electronics troubleshooting manual that can be viewed online for free that will guide you through each step of the testing.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

I did some diagnostics on the engine, but was looking at the wrong engine!!! I need that service manual!! Stupid Clymer book, so I have to redo the ohm readings. But I located a video on youtube that shows the EXACT same problem that I am having with this engine. It sounds exactly like this guys engine. I am going to see if I can locate that diode and see if that resolves mine too. Let me know what u think..

1995 Johnson 150 Fast Strike motor troubles - YouTube

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

That is certainly a possibility. I don't have the manual for your engine, but on my 1988 the blocking diode is in the shift interrupt switch harness. The two wires from the switch are covered by a plastic sleeve. When I run my hand down the sleeve, I can feel a lump were the diode is spliced in. I have no idea if its the same on your engine, but it's a place to start. Before you posted the video link, I was thinking that it might be a bad shift interrupt switch if you engine has one. You can try disconnecting it and see if it runs better. Depending where that diode is located, you might be taking both of those components out of the circuit when you disconnect the switch.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

If you don't have a factory manual, you should be able to get the correct test specs from the troubleshooting info at: cdielectronics.com

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Here's the new link to the CDI troubleshooting manual.

http://issuu.com/cdielectronics/docs/cdi_troubleshooting_guide_-_2012_1/1#print
Click on the manual to read it online.
You can print individual pages without creating an account with issuu dot com.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Thanks guys. I did a search for Blocking Diode for johnson and i found the CDI website. It was their troubleshooting procedures that I was following when I figured out that blocking diode may be the problem, the video confirmed.

I disconnected both tan wires from the thermostats and the engine would rev above 3500rpm. (My tach may not be accurate) but it wasn't surging like in the video. When I connected the port thermostat, engine would still rev. When I connected the starboard thermostat connector (The one that has two wires) the problem started happening again. This is the kicker.. I connect the black and white wire that comes from the starboard thermostat but leave the tan connector that is on that same thermostat disconnected and the engine will rev fine. Is that a bad thermostat??? Or could the diode still be the issue? Greg, I was having problems locating that darn diode. But when u said it was wrapped in plastic with two wires, I think I have found it. I have a connection right on top of the engine where the tan wires plug together and they are wrapped in heat shrink sheilding. I didn't get a chance to x-acto blade that off tonight, but its high on the priority list tomorrow. I want the boat back on the water, I 'm missing some good fishing!

I'm on the edge of a touchdown!!! Guide me home... Thanks for all ya'll assistance!!

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Just in case u wanted to see if u could find the wiring diagram. My motor info. '89 Johnson GT 150 (J150STLCEM)

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Why not just test the Diode ?

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

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The diode on the smaller engines is in the engine harness. I think you probably located it.

You should be able to test the diode by disconnecting the big red plug and putting the meter on the tan wire on the plug + to the tan that goes to the over temp sensor - and then reversing the meter leads. The diode could be breaking down at high RPMs so I'm not sure that is a 100% test.

Also, you do have a functioning warning horn Correct?

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Nymack - I had completely planned to do that. But I have to see the diode to find out what the resistance of it should be etc etc. I'm not too good at testing components, but I have done it before. Besides, it may be easier after all this to just put another one inline. Heck I can solder like a pro! I think the diode would be all of 2 bux at Rat Shack ya know???

Ok Greg, that is something I hadn't gotten to just yet... I was trying to fix one evil at a time. I have NOT heard a horn sound from this motor since I bought it. That was a question I was going to diagnose later after I got the motor running good. The things I would be worried about is new. (Fuel Pump with Vro connected new! 418.00!!!!!) Which made a HECK of a difference in the way the motor ran!! I guess the cleaning of the carbs and setting the floats probably went a long way to helping it idle like a champ too. The guy I bought it from said it was giving him tone codes when he was using it, but I have not heard one tone. Maybe he disconnected it?? I have not started figuring out where the horn is located/connected cuz I bet he disconnected the horn so it would "Shut up". Of course he didn't know the tone codes or anything. He was not a "motor" kind of guy.. He took it to the shop, soooo.... I think this problem stumped the shop and he wasn't willing to put any more money in it since he had already bought a bigger and badder bassboat.

If I left the B/W wire connected and the port side temperature sensor connected, the motor would rev fine. Its the tan wire that is connected to the same sensor as the b/w wire on the starboard sensor. If I connect that tan connector to the harness thats when the motor starts acting a fool. Anytime that wire is connected, the motor starts hunting again. Since that diode is inline, if its faulty it could be allowing some signal to go backwards and is confusing the readings from the temperature sensors??? Cuz it looks like the sensors signal is connected at that junction point where the diode is inline to send a "joined" reading to the timer base is my guess.

The weather here has been gusting at 40mph and 40 degrees. Guess what my allergies did! So I am hoping to get out and work on it today. We will see!

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

Click on the image that Nymack posted. It will show two meters with the approximate reading you should see if the diode is good.
most meters have a diode check function. Just set the knob to the diode .

Sorry. I misread your earlier post. I thought it was running bad when the B/W wire was connected. It's probably the diode. I'm going to delete my previous post, as it does not apply and will only confuse people who read this thread.

If you have the binnacle style control with a separate key switch the horn is probably behind the gauges. Look for a purple or blue wire coming from the A terminal on the ignition switch and the tan wire. The horn is probably clamped to the wiring harness. If you have the old style remote control box with the integral key switch, the horn is inside that. It may be as simple to fix as unscrewing the two halves of the horn and cleaning the contacts

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

I checked the Diode, and I got .613 one direction, and no reading flipping the leads around. If its suppose to be 1k +/- 25%, then marginal would be .850. So that must mean that my diode is bad. Its almost 50% of 1k, so that would give a false reading to the timer base assembly and gives a false reading. So I'm gonna get out of here pretty soon and purchase a new diode, and see what it says. Say a prayer for me! I will be so happy if this does it.

Re: '89 Johnson GT 150 - Won't Past 3000 RPM, Surges..

I went to purchase another diode at Radio Shack, and they didn't seem to have it. (I think they are lazy and needed to cross reference it) so I went to fry's and they matched it up to a NTE580 Diode. NYMack maybe u have some electronic experience, but I want to make sure that this is a direct replacement for it. The one that came off the Harness was a 1N5397 8819 diode. Does anyone know for sure if this diode will work? It is a 3amp, but thats ok. 600v instead of 700v and I think that would be fine too. Its the other numbers that I'm not sure of. Does anyone have any knowlege of this?? I'm just hoping for a response before I try it.