06 Johnson 90 2 stroke slow activation

[nycfyrman]

I posted about this last year and got some great feedback. But after replacing the power pack and optical sensor it ran great for a while then started activating slow. I rerouted my starboard side temp wire and that made it go away. I then went back out and it did it again. So this time I disconnected the port side temp switch and it seems to be gone. But it’s a pontoon boat so it doesn’t really “run” that much especially on my short 2.5 mile lake. I know it’s not overheating as I can put my hand in the water tell tale without any cursing. My water temp now on the lake is about 75 here in NY. I have read about the diode but I don’t think it’s that. What I would love is to find a factory manual but I have looked everywhere and can’t find one. It does not have the vro I removed it when I suspected it was causing a fuel starvation problem.

Thanks for the help!

 

[Chris1956]

Try the Marineengine web site for a service manual. You will need your model number.

I suggest you test your two head heat sensors. If either of the tan/blue wires are connected to ground, when the sensor is cool, it is defective.

 

[nycfyrman]

It’s intermittent that’s my biggest problem! Will do it, throttle back, it stops, proceed again does it again, and I mean go below 2500rpm and then go again it’s fine.

 

[racerone]

You are sure that motor is not mounted too high ?----Was water pump serviced recently ?------You are now running with temperature warning horn bypassed ?----Any other trouble shooting done.-----What fuel pump is on the motor now ?

 

[nycfyrman]

You are sure that motor is not mounted too high ?----Was water pump serviced recently ?------You are now running with temperature warning horn bypassed ?----Any other trouble shooting done.-----What fuel pump is on the motor now ?

If the motor was any lower it would be a underwater. The fuel pump was purchased from a marina down in Florida they have sold hundreds of them as a replacement. The water temp while running is Luke warm, and the amount of water is like my 4 year old taking a leak! It being a pontoon boat access to the motor is a nightmare. Im gonna go for a ride with the sensor disconnected again and see how it runs. I find it odd that the sensor would do this but hey, you never know!

I assume I should check the sensors when its idling as the thermostats are closed and see what if I get continuity to ground correct?

 

[nycfyrman]

So I ran it with the sensor disconnected for about 20 minutes ran like a champ! Now i need to reattach it see if it does it. I hate wasting money on parts

 

[Crosbyman]

The water temp while running is Luke warm, and the amount of water is like my 4 year old taking a leak!

wish I could pee like a 4 year old

 

[nycfyrman]

The water temp while running is Luke warm, and the amount of water is like my 4 year old taking a leak!

wish I could pee like a 4 year old

Talk about a time saver! And I’m only 44!

 

[nycfyrman]

So I reconnected the temp switch on the port side of the motor and it immediately started to fault in to slow mode. Anyone know how to test this thing? I checked for a ground but it didn’t give me one. I just assume it’s it because it’s doing it. But 200 bucks is a lot of I guess it’s this!

 

[Chris1956]

When temp switch detects overheat, it shorts the tan/blue wire to ground. So install it cold, unconnected and put an ohmmeter on the tan/blue wire and see if it is grounded to the block. If not check the balance of the tan wire from it for a bare spot that could ground when it is connected.

 

[nycfyrman]

When temp switch detects overheat, it shorts the tan/blue wire to ground. So install it cold, unconnected and put an ohmmeter on the tan/blue wire and see if it is grounded to the block. If not check the balance of the tan wire from it for a bare spot that could ground when it is connected.

I had done a continuity test as I couldn’t find any values for the actual sensor to test. The motor probably doesn’t even get up to temp really because the lake isn’t that big. I’d bet this thing doesn’t even have 200 hours on it.

 

[racerone]

Motor will be up to temperature after about 2 minutes of running.----Size of the lake would not matter.

 

[nycfyrman]

Motor will be up to temperature after about 2 minutes of running.----Size of the lake would not matter.

Is the tell tale an accurate way to measure overall temp of the motor? I’m old school I’ve never had a temp gauge on a boat. I just make sure I hear it pissin. The lake doesn’t have large weeds so obstructions aren’t an issue either.

THANKS EVERYONE FOR THE RESPONSES

 

[racerone]

No it is not.----On many motors the tell tale water does NOT circulate through the block.------It indicates that water pump is pumping / working.----It does NOT indicate that motor is cooling properly !!

 

[nycfyrman]

No it is not.----On many motors the tell tale water does NOT circulate through the block.------It indicates that water pump is pumping / working.----It does NOT indicate that motor is cooling properly !!

I’d venture to say though on this motor it does as it does fluctuate in temperature.

 

[Chris1956]

Gee, the overheat sensor is a temp switch. It is either open or closed. No other resistance value is normal. When the temp sensor is cold it should be open. When hot it should be closed.

It is likely just a piece of wax inside the sensor. When hot the wax expands and pushes the contacts closed, grounding the tan/blue wire. When the contacts close, the ground is sent to the powerpack, telling it to go into SLOW mode.

 

[nycfyrman]

Gee, the overheat sensor is a temp switch. It is either open or closed. No other resistance value is normal. When the temp sensor is cold it should be open. When hot it should be closed.

It is likely just a piece of wax inside the sensor. When hot the wax expands and pushes the contacts closed, grounding the tan/blue wire. When the contacts close, the ground is sent to the powerpack, telling it to go into SLOW mode.

I agree but when I tested it I didn’t get anything! But when I unplug it the boat runs fine and this is upon immediate start up.

 

[Chris1956]

Usually those V4 motors have a two wire heat sensor and a 1 wire heat sensor. The 2 wire heat sensor also controls Quickstart. So when cold, the white/black wire is grounded. When overheat the tan/blue wire is grounded.

Also, whenever the motor is started, hot or cold, it will go into Quickstart mode for a few seconds. If the motor is cold, the Quickstart mode will stay on, due to the sensor, until the motor warms.

In any case, it sounds like you have enough evidence to replace the sensor, provided the motor is not overheating.

 

[nycfyrman]

So yesterday I made four attempts at confirming it was the temp switch and not something else by connecting and disconnecting the switch and running it. I ASSumed that because the retaining clip for the switch plug was attached to the wiring harness that it was in the proper place but after it running fine with the it plugged in I figured that it was probably IF from the plug wires. I disassembled the plastic cover in the starboard side and rearranged the zip ties and wires to allow me to get the lead wires further away from the plug wires and so far it’s operating normally. I will run it a bunch this week to verify and report back so if anyone else Google’s this a solution will show up. Thinking of maybe wrapping the wires with metalized hvac tape to further provide isolation from interference.