50hp johnson high speed alarm, bogging

[ne-boater]

looking for some help on this one, tried almost everything... i've got a 99 johnson 50 (j50pleea) that runs excellent from idle to maybe 1/2 to 3/4 throttle, then the alarm will chirp once or twice (very rapidly) and the engine will bog but not quite die...
i've already replaced the pump and t-stat to eliminate overheating, even though i know it isn't a steady overheat alarm, and the raytech laser heat gun shows it is not getting hot.
i've also tied running it with both the oil tank sensor unplugged as well as the harness from the vro pump unplugged, running on pre-mixed fuel from a remote tank, with the same results, horn will only chirp one or two urgent tones and that's it. i thought it could be a problem with the alarm circuit itself, and unplugged the alarm, still get the same results but without the chirp.
i am going to be looking at the pulse fitting (couldn't get it out with the tools i had last time) and maybe looking at replacing the vro pump with a straight fuel pump but i am not convinced this will solve my problem. i might suspect carbs if it wasn't for the alarm beep, but it is inconsistent with 'normal' alarms...
any insight would be greatly appreciated.
thanks-

 

[ne-boater]

Re: 50hp johnson high speed alarm, bogging

let me add i've removed the oil line to the engine while running pre-mix to sound the no oil alarm, and it was not the same alarm i get when it bogs, i then reconnect the oil line to the engine and it primes itself and the alarm stops, oil flow looks good, pick up in tank is ok as well...

 

[ne-boater]

Re: 50hp johnson high speed alarm, bogging

where are all the johnson experts?

 

[Seasport]

Re: 50hp johnson high speed alarm, bogging

Some of the motors also sound an alarm when there is a fuel restriction (causes lean running which is bad for your cylinders). Not sure if yours is one of them.

Does the primer bulb go flat? Does pumping the primer bulb cause the problem to go away. Check for fuel restrictions somewhere.

 

[Walker]

Re: 50hp johnson high speed alarm, bogging

The fuel restriction alarm is a tone about every 40 seconds if I remember right. I think Seasport has good advise.

 

[ne-boater]

Re: 50hp johnson high speed alarm, bogging

thanks for your reponses...
i do not have the fuel restriction alarm, and i did try pumping the primer ball though it wasn't flat and it made no difference...

 

[ob]

Re: 50hp johnson high speed alarm, bogging

If the alarm is sounding as you say with the vro harness disconnected as well as the oil reservoir harness disconnected,the only sensor leads left in the alarm circuit are from the overheat sensor.This also initiates the S.L.O.W. feature which will drop the rpms to around 2500-3000 regardless of whether the engine is actually overheating or not.

So, my guess is that your engines overheat sensor is intermittedly making contact and causing your issue.

 

[Seasport]

Re: 50hp johnson high speed alarm, bogging

Good point ob. You can disconnect the tan wire going to the temp sensor and see if this fixes the problem.

 

[ne-boater]

Re: 50hp johnson high speed alarm, bogging

thanks, i will try disconnecting it to see if it is causing the alarm. i overlooked disconnecting it initially as i was sure it was not overheating.
thanks-