1988 Johnson 90 HP issues

[BallisticRenegade]

I just picked up a 1988 Johnson the first time out after installation, about 4 mins at full throttle, the engine backed the RPMs down to a high idol and would not go above.

To Start the run we went slow for the first 10 min to warm up and due to low water levels 4 feet or so. Then when in 8' of water we ran it up. 3-4 min into the run engine limited back.

Symptoms:
Turned off and restarted no prob
Throttle up starts RPMs up for a second then limits down since first limiting event
throttle up with prop not engaged revs all the way up
the tell tail seems to be throwing a very strong stream

Work Preformed:
checked Plugs/ wires and replaced
Found bulb leaking some small amount of fuel, replaced everything including tube/bulb/johnson fuel adapter.
checked Fuel filter good
oil bulb is hard
Fuel bulb was hard tried squeezing no help during limiting event no help
Compression is good on all 120+
Found the warning siren faulty and replaced
Found the VRO causing an alarm with Siren so bypassed for now and mixed fuel

The question is what else can I do to check into why it shut down before I take it back out and if it happens again what should I do before taking it to the dealer?

Things I am debating:
Pulling the head to check over heat probes water deflectors thermostats
Replacing the water pump
I have NO experience with outboards or motors but I am mechanically inclined. I am debating just taking it in or to try to do these items because I know the Marina will for sure. I found an e-bay kit that give me Head gasket, thermostats, water pump and a few other items for $125 to do the repair if I can do it.

Can the newbe do these things?

I have also been on marineengine for this issue here is the thread: www.marineengine.com/boat-forum/showthread.php?402182-Johnson-90-hp-1988 this has a few more details as I go along.

Please Help if you can.

 

[BallisticRenegade]

Re: 1988 Johnson 90 HP issues

So I have established that the VRO was not working properly (incorrect power applied) The motor has ran for about an hour with out oil mostly at low RPM. Am I good to premix and get back on the water to test it or do I need to get it to a dealer for a damage assessment?

Some one with a VRO can you please verify where the wires go? I know one goes to the Tan alarm wire where does the second one go? to the positive battery terminal? Please let me know.

 

[Chris1956]

Re: 1988 Johnson 90 HP issues

First check the compression. If it is close to even on all cylinders, replace the waterpump. What you have described may have been the motor going into S.L.O.W. mode. I am not certain you have this mode, but it is likely.

Check the overheat sensors. Heat on stove in water and check temp. They should ground as water nears boiling point. Test thermostats the same way. They should open at 140*F.

Maxrules web site has wiring diaghrams. That will help with VRO wiring. Keep premixing until you get it sorted out.

 

[AEROCOOK]

Re: 1988 Johnson 90 HP issues

So I have established that the VRO was not working properly (incorrect power applied) The motor has ran for about an hour with out oil mostly at low RPM. Am I good to premix and get back on the water to test it or do I need to get it to a dealer for a damage assessment?

Some one with a VRO can you please verify where the wires go? I know one goes to the Tan alarm wire where does the second one go? to the positive battery terminal? Please let me know.

Your comment about incorrect power applied has me confused. The VRO pump on the motor is operated by pulse from the crank case, it's not electric, the wires on the pump are for the alarm system. The fact that the motor was running means the gas side of the pump was working and it's likely that it was pumping the oil too. I have a 110 of the same vintage and like many other folks, I've converted to 50/1 premix.

 

[BallisticRenegade]

Re: 1988 Johnson 90 HP issues

Thanks for the reply's guys.

Chris I have established I do not have SLOW on this motor. It does sound like exactly how they describe it however it does not have it.
The compression is good on all cylinders at 120 psi.
How can I get to the Thermostats? I know where they are however is it just dropping the lower cowling to get there for removal?
Is it just popping off the top cover where the spark plugs are to get to the temp sensors?
I can run premix AND the pump without issues?

Aerocook:
I did not understand they were just alarm wires to begin with (I guess the complexity of it made me think it was a pump). That being the case I have been told one goes to ground and the other goes to the tan wires. Can you confirm? When I do this the system alarms a constant tone. I have pulled the assembly in the oil tank and shook it around but this has not produced any significant result.

Thanks for the response guys keep them coming.

 

[AEROCOOK]

Re: 1988 Johnson 90 HP issues

Here is what mine looks like, it's a 1988 110 hp. I made a point of positioning the wires in the same configuration as the pins in the connectors. The second picture is the plug that comes directly off of the VRO pump.

 

[BallisticRenegade]

Re: 1988 Johnson 90 HP issues

Thanks for the pictures.

Those wires are to the pump. Can you look to see where the tank wires route? The Tank wires is what is causing the alarm.

I went to mastermarine and his electrical diagrams only show a tan wire to the tank no second wire. I dont think that will work either.

 

[AEROCOOK]

Re: 1988 Johnson 90 HP issues

I no longer have the oil tank, as I mentioned earlier I've disconnected the VRO system and now run 50/1 premix.
The debate about the reliability of the VRO systems is as old as the hills and I can only offer my personal opinion. The reason I disconnected mine is because I'm the only one who fills the portable fuel tanks on my boat and I'm 100% confident in my abillity to accurately mix my oil and fuel. I no longer have to question whether of not the VRO pump is doing it's job. The VRO delete procedure will not cost you a cent and takes no more than 10 minutes.

 

[BallisticRenegade]

Re: 1988 Johnson 90 HP issues

Sorry I was blinded with excitment that I may have found someone who knew where they went when I saw your pictures.:facepalm:

So the plug you have pictured you leave "unplugged" to eliminate the OIL pump portion of the VRO2 pump on your 88? Or you leave them all connected and just pull out the VRO oil tank and wires? capping the oil line I understand. That has been a looming question when I have been reading other posts.

Have you ever serviced your thermostats? IYP what is the best way?

 

[rothfm]

Re: 1988 Johnson 90 HP issues

A thermal IR gun can take some temp readings real quick. If your runnning hot and dont know it, all this "testing" can be doing damage. Verify your running, and remaining at proper operating temp.

 

[BallisticRenegade]

Re: 1988 Johnson 90 HP issues

I have one of those I have been using. Thanks for the tip Rothfm. What is the proper operating temp? I have not let the heads get above 150 on the hose. No more than 10 min of run time and do not go above 1500 RPM in gear.

 

[AEROCOOK]

Re: 1988 Johnson 90 HP issues

Sorry I was blinded with excitment that I may have found someone who knew where they went when I saw your pictures.:facepalm:

So the plug you have pictured you leave "unplugged" to eliminate the OIL pump portion of the VRO2 pump on your 88? Or you leave them all connected and just pull out the VRO oil tank and wires? capping the oil line I understand. That has been a looming question when I have been reading other posts.

Have you ever serviced your thermostats? IYP what is the best way?

As for the thermostats, yes I have replaced mine and it was a PITA but mine is a bubble back and yours is a flat back which makes yours a little easier. There are lots of posts on the topic of thermostat replacement with a lot of helpful tips.
As for the wiring question, although my VRO is disconnected my wire harness is intact so I can provide you with more info on wire color and location etc. when I get home from work tonight. If you opt to disconnect the VRO the only part of the alarm system that you will leave plugged in is the temp sensors in the heads.

 

[BallisticRenegade]

Re: 1988 Johnson 90 HP issues

Thanks Aero.

Just to clarify there is a connector going to the VRO pump that is in need of disconnecting ( pictured above) and the two wires running to the VRO oil tank. correct? Thanks for tracing them out as well. I have the unit back to the guy I purchased from. I have not decided if I am going to keep the VRO or not I guess that will be dependent on a new $150 oil tank unit needed or not.