2001 johnson 90 hp running rough & over heating

[BillProctor]

I appreciate all replies.. My 90 hp 6 cyl at around 2500 rpms starts running very rough like several cylinders are missing. Under 2500 it is very smooth and runs fine. If I try to push it the overheating alarm will come on. I've replaced the plugs and one fuel line but no change. I need several ideals on how to trouble shoot this. Does the motor have a thermostat?

 

[flyingscott]

If it overheats have you checked the water pump?
Also need a model #.
Are you sure it's a 6 cylinder and not 4.

 

[BillProctor]

You are correct it is only 4 cylinder. model #J90PLSTC. Water pump seems to be working fine. strong stream of water coming out.

 

[flyingscott]

Is the vro hooked up? And which alarm are are you getting?
Solid tone?
1 beep every 20 or 30 seconds?
1 beep every second ?

 

[BillProctor]

It beeps every few seconds. not sure the timing. What is the VRO tone like? I've order a manual but it hasn't gotten here yet.

 

[flyingscott]

If it is beeping every few seconds that is an oil flow alert that tells you there is not enough or no oil.. DO NOT RUN it until you figure out why it is beeping or run pre-mix in the motor at 50-1 until you figure it out.. Wait for the manual hopefully it is a factory manual it will tell you how to test the VRO pump. The motor is running rough because the S.L.O.W mode is engaging it is a safety feature.

 

[jakedaawg]

I'll add that any further running/testing must be done with 50:1 premix in portable tank until VRO is confirmed good. Double oil will not hurt anything.

Edit: oops, sorry, that was already mentioned.

 

[daselbee]

Come on guys...let's get accurate here....

A 2001 90hp surely has Systems Check. That would be a gauge or a tach with four lights. If overheating, the horn will sound solid for about ten seconds and the hot light will turn on.

There are no more multi tones from the alarm. You have to examine which light is lit for the fault.

If it is overheating, the HOT light will be on, and the engine will go into SLOW mode, which limits it's RPM to 2500 or thereabouts.

Is that what is happening?

It is a 2003 too, by the way.

 

[flyingscott]

Come on guys...let's get accurate here....

A 2001 90hp surely has Systems Check. That would be a gauge or a tach with four lights. If overheating, the horn will sound solid for about ten seconds and the hot light will turn on.

There are no more multi tones from the alarm. You have to examine which light is lit for the fault.

If it is overheating, the HOT light will be on, and the engine will go into SLOW mode, which limits it's RPM to 2500 or thereabouts.

Is that what is happening?

It is a 2003 too, by the way.

Maybe you should read post #5 where he is getting a beep every couple seconds. Also no mention of a light.

 

[daselbee]

Maybe you should read post #5 where he is getting a beep every couple seconds. Also no mention of a light.

I read it. So? Means nothing, except something doesn't match up with the way IT IS SUPPOSED to work.

 

[flyingscott]

I read it. So? Means nothing, except something doesn't match up with the way IT IS SUPPOSED to work.

You are right I am not standing in front of it like you obviously are.

 

[jakedaawg]

well, lets ask the OP. BillProctor Do you have a tach with the four lights at the bottom, or do you have a stand alone system check gauge with the four lights? Also, if so, does your system beep once and have the lights illuminate and then go off one by one when you first turn the key?

daselbee Good catch, however, I was under the assumption that it was possible to have the different horn tones on later motors. Guess I have not actually run across this yet with the exception of a low oil light on a 2000. It does not light the light but does give the slow beep. I assumed a bad guage but nobody wanted to pay for diagnosis/repair because the horn was alerting them. It is the system check guage that determines horn sounding and lights? The oil tanks and vro still send the same signal by intermittant grounding, correct?

 

[daselbee]

All the tan sensor wires go thru the harness up to the tach (gauge). They hit the tach in an eight pin connector, and if you examine all the individual wires you will see tans with varied colored stripes...just like you would see back at the engine. I used to know the colorof stripe vs. function, but don't remember anymore.
The tach then "figures out" which alert to sound...by the fact that the appropriate tan wire has grounded due to overheat, low oil, no oil, and on V6s, Check engine.

The tach turns on the horn, and lights up the light. Now the million dollar question....I am not sure about the low oil, for instance. I know it will light the light, but I am NOT sure if it produces a different sound from the horn.

I know for a fact that overheat will turn the HOT light on, and sound the horn for about ten seconds, then the horn shuts off. You have to look at the tach to see which light is lit.

Another quirk is that you cannot test the Systems Check FULL functionality without starting the motor. The motor has to be running. If you try grounding a sensor with key on like everyone is used to testing....the light will light up on the tach, but the horn will NOT sound. The horn only sounds with the engine running.

Now, I have been silent on this post waiting for clarification from the OP also. OP???? Where are you?