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I have a very interesting issue going on with my outboard right now (2001 Merc 135 DFI about 120 hours). I have been using it since the start of walleye season in may and up until now no issues at all. Yesterday I was fishing and when i was running down the lake the 4 beep oil low alarm sounded, no big deal I add oil and restart it. The 4 beep continues, take off the cowling and had to bleed the air out of the on board oil tank which was new last year after the sensor failed. Once i did that the beeping stopped and all was well. While running the lake something very stranged happened that I've never experienced before. Every time the RPMS reach EXACTLY 4700 RPMS i get a constant beep alarm going off that I haven't heard before. The strange part is that even if i throttle back to 4600 RPMS it goes away. Has anyone had this before. I haven't found anything like this while researching. I've been on vacation at a cottage for a week and have had 0 issues up until that point. I know a constant beep could mean water pressure but there is plenty of water coming out when running at idle or on plane. If it was over heating shouldn't it go into guardian mode it doesn't do that either it just runs and beeps. It sounds like it might just be a faulty alarm going off but am not 100% sure of that. I plan on calling my mechanic tomorrow but if anyone has had this happen before would be nice to hear what was the fix.

Brian

I had a similar situation on an 06 Optimax. Mine was a throttle sensor that was faulty. Sensor thinks you are in neutral and freaks out that you are revving it at 4700 rpm in neutral.

I won't get into the different marinas around town that charged Merc a ton of money under warranty to not fix that problem

Mick wrote:I had a similar situation on an 06 Optimax. Mine was a throttle sensor that was faulty. Sensor thinks you are in neutral and freaks out that you are revving it at 4700 rpm in neutral.

I won't get into the different marinas around town that charged Merc a ton of money under warranty to not fix that problem

if you don't want to name marinas that gave you a sunshine job, why not tell us how you fixed it?

it got fixed by a local small engine guy correctly diagnosing it as a throttle sensor issue and replacing it....10 minutes of work if you diagnose it correctly

I had it at 2 Ottawa valley marinas both of whom took umpteen things apart, charged Merc a ton for warranty work, told me I was good to and I never even got the boat fully trimmed out of the water before the alarm went off again...one of those marinas was on water so it should have been ...you know...pretty easy to test. I recall I lost about 6 weeks of prime fishing season that summer with the boat in the shop

based on description....it sounds like the same problem to me....but I'm a fisherman, not a mechanic

Luckily ive got 2 marinas that i trust to not waste my time and money i will make sure i mention the throttle control sensor because like you said that is probably the cause of the issue. They couldn't see it today since it has been a constant downpour today and they dont want to waste my money buy trying to recreate in the shop when the best way to do it is to test it on the water. first thing tomorrow i bring it in and hopefully get it back by end of the day, Thanks for the replies will follow up once i know what it was.

Brian

same issue on 2001 Optimax 225... was a cracked oil reservoir under the motor cowling... simple fix

My Merc has a similar alarm for "overheat", which is good because the impeller jammed and stripped the key, result was only a trickle of water at idle (so I thought it was working) but not enough at WOT, resulting in the beep.

Good new is that it was nothing serious. All it was was a couple connectors that hooked up to different sensors came unplugged. Probably happened when i took the cowling off to bleed the air out of the onboard oil tank. Thankfully nothing worse and was only out of the water for 3 hours.

scarkner wrote:My Merc has a similar alarm for "overheat", which is good because the impeller jammed and stripped the key, result was only a trickle of water at idle (so I thought it was working) but not enough at WOT, resulting in the beep.

I'm having the same issue.