25 Johnson Alarm & SLOW mode

[PAULMN]

This refers to a 1996 25hp 2 cyl Johnson remote. The motor first began loosing power on an intermintent basis. The power loss is now full time. The alarm now goes off from the begining of start up, and I believe the motor is running in SLOW mode. The motor can not be overheating (good water flow ect). The following has been replaced (belive it or not) Plugs, Fuel Hose, Fuel pump, coils, and rectifier. It was later found out that someone had inadvertanly crossed the negetive and positive battery conections, (one wire going into the rectifier melted). All fuses have been checked, and no wires seem to be pinched frayed ect. Could it be the power pack? You may ask why so many parts have been thrown at this,, it is on a pontoon boat in a very remote area.

 

[PAULMN]

Re: 25 Johnson Alarm & SLOW mode

^

 

[Solittle]

Re: 25 Johnson Alarm & SLOW mode

Don't assume that it is not overheating because you have a good flow from the telltale. I do not think that this is your problem though due to "The motor first began loosing power on an intermintent basis."<br /><br />You need to get the shop manual and follow the troubleshooting guides.

 

[ob]

Re: 25 Johnson Alarm & SLOW mode

PaulMn,How did you arrive at the fact that the engine was going into the S.L.O.W. mode? Did the rpms suddenly drop to the lower rpm level while running or did the engine have trouble getting up to speed when this problem began.What is the condition of the thermostat?<br />I'm trying to determine whether we are chasing a temp problem or fuel/spark issue.

 

[PAULMN]

Re: 25 Johnson Alarm & SLOW mode

The reason that I suspect the motor is in S.L.O.W. mode, is that it starts fine, a constant horn under the dashboad begins imediately (and does not stop). It would seem the motor would not have had a chance to heat up yet. When you push the throttle it reachs a certain RPM,, (no tach), and starts vibrating. If you push the throttle more than 1/3rd the engine realy spudders (vibrates), and no additional acceleration occurs. I will check the thermostat condition

 

[ob]

Re: 25 Johnson Alarm & SLOW mode

PaulMn,The steady alarm tone on your engine denotes two possibilities .Overheat which limits the rpms electronically and fuel restriction .I'm guessing that your alarm is indeed being triggered by the VRO fuel restriction sensor.<br /><br />After you have inspected and or replaced T/stat you need to insure that the fuel supply from tank to VRO pump is clear and unrestricted.Next you can test the operation of the VRO pump at cranking speed by disconnecting its discharge hose and routing into container while observing its flow at cranking speed.If all is fine there ,the next thing is to remove and clean any restrictions in carburetor fixed orifices and porting.Fouled carburetors are quite common in two stroke outboards that have sat idle for a spell.

 

[PAULMN]

Re: 25 Johnson Alarm & SLOW mode

The motor is connected via hose directly to the six gallon tank. The OMC manual indicated that the constant horn inicated a possible fuel restriction. I changed hoses, and tanks (had spares) the problem went away for one trip around the lake and returned. Could it be the carb needs cleaning? I still keep wondering if when the battery cables were reversed something fried in the Power Pack? One wire was all but melted off going into the rectifier (which I replaced).

 

[Walker]

Re: 25 Johnson Alarm & SLOW mode

I'd start disconnecting sensor (Tan) wires one at a time until I isolated the cause of the alarm. The buzzer unit itself may be bad and causing the alarm.

 

[OBJ]

Re: 25 Johnson Alarm & SLOW mode

I would have to agree with walker here. Time to start narrowing down possibilities. If the alarm horn starts when the key is put to on, and not to start, then I would have to say the horn module is faulty. Disconnect all inputs to the horn and turn the key on. If the alarm is continuous, the module is bad. If the alarm is silent, start connecting the inputs and see which brings the tone in.<br />With refference to the "frying of the rectifier", it is very possible that the reverse power surge could have had a negative (no pun intended) impact on the power pack. Especially if the key was turned on with the battery connected in reverse, something we don't know. But start with the alarm horn and work back. Just my opinion.

 

[PAULMN]

Re: 25 Johnson Alarm & SLOW mode

I am sure the key was turned on when the battery was connected backwords. I disconnected both tan leads (one at a time) going out of the power pack, The alarm still goes off continuous, and still no power. I assumed it was the power pack,,, The local marine dealer did not have one in stock,,, He said I was probably correct with the power pack (because the S.L.O.W. mode could be effected by the Power Pack), but I should check the stator first?