1995 johnson 150 slow mode? I'm stumped please help!

[pioneer11]

Ok guys I have a 1995 Johnson 150 The engine starts and runs great but will not rev past 2500 when warm. On initial start up it will rev right up but when I put it in gear and get on plane it cuts off at 2500 and when I slow to idle put it in neutral still wont rev. let it cool for half hour still wont rev.

have tried pumping primer while revving no change.

Engine runs great at 2300 rpm but will not go any higher.

I have read there is a diode somewhere in the harness that could cause this? Where in the harness? and what does it look like? Is there more than one?

Previous owner ran it hot. not hot enough to do damage as it compression tested perfect.

So far I have replaced impeller kit head gaskets plugs drained fuel cleaned fuel filter added inline filter . thanks again guys.

 

[pioneer11]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

am I on the wrong forum?

 

[multimech]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

No you are not on the wrong forum.

Does your setup include a tach or seperate gauge with 4 lights? Does your setup have an alarm? If so are you getting any type of alarm?

If not, then you probably have a mechanical problem. Carburation. Ignition. Usually S.A.F.E mode limits the engine to under 1800 RPM. This does not sound like your scenario.

Check your prop. Dinged, bent? Check the bottom of the boat. Any barnacles? Is the boat too heavy from water coming into the boat that you are not aware of? There are a number of scenarios that could cause your problem.

 

[seahorse5]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

A 1995 engine does not have the 4-light System Check warning guage - unless someone did an expensive jury rig as it did not come out until 1996.

You engine may be only running on 3 cylinders due to a shorted shift interrupter switch. You have to do the basics first to check out the ignition system, fuel system, and internal engine condition.

If the boat has just come out of storage, you may have plugged jets.

If you do not have the skills or want to learn the skills of troubleshooting - take it to a knowledgeable mechanic for diagnosis.

 

[pioneer11]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

My boat came with the system check gauge the boat is a 99 stratos and someone has disconnected that gauge and installed a 95 wiring harness on the engine. . it has a 3 wire alarm that is new. I am not getting overheat or anything like that as I have two temp gauges installed and they stay at the same temp at idle.

I have looked in the harness for the diode and I can't seem to find it anywhere. It is really strange because the engine revs when first started then will not rev again.

The boat just left the mechanic last week he replaced head gaskets impeller. said the engine is a fresh rebuild and they used old gaskets to put it back together.

I don't think it is carb related as it is consistant at 2500 rpm it cuts out.

 

[pioneer11]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

Just started boat on hose when I first started it engine revved to 3000 5-6 times. All seems right, put it in gear and engine will not rev past 2500 rpm. back to neutral same thing will not rev. shut off restart will not rev.

Disconnected tan wires from temp sensors no change, disconnected shift switch no change.

Power pack issue? It seems like something is telling the power pack to cut off when it is in gear to me. Or is the power pack fried? Weird that it revs fine before going into gear. then wont rev at all after it cuts out.

This is on a hose connected to the tell tale and no prop.

also cannot for the life of me find the diodes?

 

[pioneer11]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

Ok so I disconnected both temp sensors and it revs right up in gear many times I reconnected temp sensors one by one and when I got to port side bam 2500 rpm limit again!

This is a brand new temp sensor!!!!

My question now is do I need these sensors hooked up? I am running two temp gauges one per bank.

I know these temp sensors set off the alarm but I have gauges so I don't need the alarm.

Also read that they have to be hooked up so it doesn't stay in quick start? How do I know it's in quick start? Do I even have it? 95 Johnson 150 vro disconnect.


When I push in key I hear a click I assume it's a choke?

I can leave the starboard side temp sensor hooked up and it will still rev out. and the port side has the white wire still connected So is one enough?

 

[HenryB]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

I guessed at your model number, but the diode should the same for all the harnesses. Plug in your model number to make sure.

Go to a parts store and call up your information.

ITEM #26, DIODE, #0583898, is on the site I used.

You will have to peel back some of the cover. It’s obvious. Change out is easy.

Quick Start advances the timing by around 5 degrees (This mode is ony for starting a cold engine, it is not associated with SLOW, which cuts out two cylinders when a hot condition is detected, and does not let the rpms exceed 2500.

To disable the quick start

Disconnect the white/black wire at the sensor, port side cyl.

Remove the Power pack cover. ground the white/black wire at the pack terminal block (the other end of of the wire you disconnected the at the cylinder)


Disconnect the yellow/red wire coming from the pack.

Note the idle rev's. when cold

Reconnect the wires.

Note the idle rev's. when warm.

No change your power pack has a problem.

 

[seahorse5]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

From your description you do not have a diode problem. All the diode does is keep the other warning senders from putting the engine into the SLOW mode as the temp switches do. You have a problem with the wiring or a temp switch. Use an ohmmeter to see if there is continuity between the tan wire and the engine ground at the offending switch. If so, then it needs replacing.

If not, then there is a short between the tan wire in the wiring harness and the power pack.

 

[pioneer11]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

I am not trying to disconnect quick start I am wondering since my port temp sensor is putting the engine into slow I have disconnected the tan wire will this keep the engine in quick start?


I went all through the harness and couldn't locate the diode. they say its right by the big red plug but I was all though there took off every cover and couldn't find it. my vro has been disconnected so maybe they have taken it out as there isn't anything else to throw it in slow other than the temp sensors.

I got my engine out of slow mode by disconnecting the port side tan temp sensor wire. Before the disconnect it wouldn't go past 2500 rpm I disconnected it while running and after a couple seconds it would rev up no problems. reconnected the tan port temp wire and would only go to 2500.

The star side is still connected as is the port white wire from temp sensor.

Will the star side being hooked up keep it out of quick start? It idles around 1000 rpm on the hose and temps are perfect.

I have two temp gauges installed so I am not worried about the temp sensor sending an alarm I can monitor both heads and I wouldn't want to just rely on an alarm hence the reason for two gauges.

Do people run without temp sensors if they are running gauges or do they need to be installed so the quick start doesn't stay on? that's my issue now...

And what is quick start just a high idle when cold and it goes back down on it's own? Also I am not sure of a model number as it's not on the engine anywhere.


Thanks!

I am assuming it is a bad temp sensor although brand new it wants to cut the rpm and put it in slow mode. I initially was told power pack but I didn't buy it because it would rev for a couple seconds cold.

 

[seahorse5]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

it is not associated with SLOW, which cuts out two cylinders when a hot condition is detected, and does not let the rpms exceed 2500.

You are mis-informed, the SLOW circuit does not cut out 2 cylinders. It disrupts the firing of all the cylinders, limiting the motor to about 2500 rpm.

 

[pioneer11]

Re: 1995 johnson 150 slow mode? I'm stumped please help!

if it only cut two cylinders it would rev past 2500 rpm. It does indeed limit it to 2500 rpm. Maybe that guy is thinking about the shift switch that cuts 3 cylinders? Not sure.

You have to take the right advice on here I've learned. You know who knows what they are talking about in the first sentence.

Thanks seahorse you saved me 700 dollars today I was on the phone with the Johnson dealer in Ontario Canada and he was saying power pack the whole time.

Like I said I wasn't buying it as it would rev for a few seconds. initially I thought it was putting it in gear that was throwing it in slow but it was the sensor telling the pack it was on fire!.

Brand new sensor..... Always the last one to check...LOL. Haven't put it in the lake yet but it revved on the hose fine.... not supposed to rev em on the hose but I had good water pressure on the hose and my temps never moved. never went past 3000 anyway.