Mercury 1993 175 hp Alarm

[wlksjstn]

I have a 1993 Trophy Center Console boat with a 175hp Mercury oil injected outboard. At the beginning of this season, I replaced the entire lower unit with a brand new unit from SEI, so I'm assuming the water pump is good. I've also recently replaced the thermostats in both heads with brand new units. When I turn the key to "on," the alarm under the helm beeps as usual. When I start the boat, it is well within 30 seconds before the alarm goes off with a series of fast beeps, and it won't stop- this is even before the engine is warm to the touch. There seems to be a steady flow of water out of the engine after it's warmed up, and the tank on top of the engine is around 7/8 full of oil. The stream will continue until I give the engine a quick rev, it'll go dry for a few seconds, then start going again...this is while on the 'muffs. I unplugged the alarm module because I was tired of listening to it while experimenting- I pulled the tan wire and the alarm did stop. Unless I'm mistaken, I thought a continuous alarm related to a lack of injection oil, and a steady beep signaled an overheat condition.

It looks like I have temp sensors in both heads; the port side head has 2 wires coming out of it, and the starboard side sensor only has one wire. It also appears that my oil injection tank on top of my engine has a pair of sheathed wires running out of the cap; under the cap there is a float switch.

I have a hard time believing it is an overheat condition, and it looks like I have plenty of oil in both tanks.

Could I have a sensor or alarm unit going bad on me? How do I test to confirm? I'd like to take my boat out this weekend, and I'd feel a lot better knowing I wasn't going to lock it up...

Thanks for your time!!

 

[wlksjstn]

Re: Mercury 175hp Alarm

Well I did a bit of testing today. I hooked back up the alarm, started the engine with the muffs on, and it was a few minutes after the water started pumping thru that the alarm started going off with a fast intermittent beep. I unplugged the sensor wire for the oil level on the engine, and it stopped; plugged it back in, and it started back up again.

I'm thinking there's something wrong with the float switch now. There seems to be plenty of oil in there; it's about 1/4" down or so from where the neck meets the tank itself. What do you guys think? Should I replace the oil pump and/or sensor to be safe?

Also, is there a way to dial back the amount of oil delivered? I typically put a new set of NGK plugs in every season, but she tends to load up rather quickly at low rpm's or under extended idling. It'll always start back up, but not always right away. I typically use the Pennzoil semi-synthetic or West Marine semi-synthetic oil, but before my last outing, I topped off the tank with some Klotz snowmobile injector oil...the good $40/gal stuff.