Fuel Restriction Alarm Question

I have a 1990 Johnson 70.

At or near full throttle, after a few minutes, I am getting a steady alarm from the control box, and SLOW kicks in. My immediate presumption is that there is a cooling issue, and I have bought a water pump service kit which I intend to install this weekend.

However, the service manual also indicates that, "on some models," a steady alarm can indicate a lean condition (ie. fuel restriction) if it occurs at or near WOT. The manual is unrevealing as to which models have this fuel restriction alarm, but I believe I recall reading somewhere that it was only included on V-configuration engines, and not on the 3-cylinders. I also understand that a lean condition will not activate SLOW.

Have I got this correct?

Re: Fuel Restriction Alarm Question

The vacuum switch that gives a constant alarm when there is a restriction on the gasoline line is not stock on your engine. It doesn't mean that there isn't one but that it did not come with one.

Regardless, you are going the right way in assuming that the horn signaled an overheat. Pull the thermostat and make sure that the housing is clear and clean after you put in the impeller.

Re: Fuel Restriction Alarm Question

Thank you for the suggestion - as a follow-up, the water pump servicing kit also includes a thermostat cover, gasket, and spring replacement, so the people at OMC obviously thought as you do.

Re: Fuel Restriction Alarm Question

Good information. Would you mind sharing the part number of the kit? I would like to write it on my parts diagram.

Re: Fuel Restriction Alarm Question

I will do that when I get home. I can also post a scan of the small instruction sheet that comes with the kit, if that would be helpful, as it details the procedure for changing the spring assembly.

Re: Fuel Restriction Alarm Question

On engines that do have the fuel restriction alarm, when the alarm goes off it will not kick the motor into SLOW. Only heat kicks a motor into SLOW.

Re: Fuel Restriction Alarm Question

Thanks for that confirmation, Dhadley. That was also my understanding.

Re: Fuel Restriction Alarm Question

70hp engines are not equiped with the vacuum switch.
onlu the 60* v6 and the 90* V6 loopers have these switches.

so you can rule that out.

Re: Fuel Restriction Alarm Question

Thanks - that was a specific version of my general understanding.

Re: Fuel Restriction Alarm Question

The part number for the kit I purchased is Water Pump Kit #432955. I would be pleased to email the file for the manual that came with it if anyone wants it.