1998 Mercury 175 EFI_Constant Beeping Issue

[mr.coon]

This has been an ongoing deal for a couple years now, since 2017. I am getting a constant beep while the engine is running. It is not the continuous overheat beep, I know that one too well. I took it to the shop, and they replaced the "oil sending unit". On my first trip out after getting it from the shop, the same alarm, constant beeping started when I launched my boat. I called the mechanic and he assured me the motor was getting oil so I ran to my spot. When I cranked up again after fishing for a while, the alarm stopped and didn't go off for the rest of the season. The next spring, 2018, the same thing happened. I ran to my spot, stopped, took the cowl off and checked the tank on the motor. It was full. I cranked her up and pulled the oil cap. The oil rose up and began to over flow the tank on the motor. I put the cap back on and fished. When I cranked up again the alarm was off and didn't sound again for the rest of the season. The oil cap on the motor did crack midway through the season and I replaced it with no issues.

Knowing the trend from the past 2 years, I put the muffs on before I headed out for my first trip of 2019. The motor fired right up and no beeping! I let her run for about 5 or 6 minutes to make sure it wasn't a fluke. Killed it and cranked it up again and no beeping. I got the lake, drove the boat off the trailer, and the beeping started before I even made it to the bank. I did the trick from that worked the previous year with no luck.

The red light on the oil sensor is not on when alarming. I tried dumping out the fuel water separator and that didn’t change anything. When I disconnect the wire from the bottom separator and connect it directly to the nearest ground, the red light on the oil sensor does illuminate. the fuel that was in the separator looks like lemonade. I put it in a glass jar and i have not seem anything separate out after sitting there for several hours. The oil tank on the motor seems to fill very quickly when i take the cap off with the engine running. When turning the key to the on position, it makes one long beep followed by a short beep sometimes and three short beeps others. I can hear what i think is the fuel pump running when the key is in the on position.

Please advise. The locals shops are backed up for weeks. If it is just a bad sensor, i can do the work myself. See my sig for motor serial number.

[JOE54]

first verify oil pump drive system is good, check grnds, possible motion sensor or module bad

[mr.coon]

Is the "sending unit" the same as the oil pump system? I spent close to $400 to get that fixed. I will get in there and check anyway.

[JOE54]

no /drive as in gears that turn pump

[EuropeanAM]

Also- CRITICALLY important: Do not attempt to turn the flywheel with the oil pump unbolted- if components are not properly retained in place and the flywheel turns it WILL strip the drive gear.

Exception being everything is removed (bearing and driven gear).

If you are not 110% confident in your abilities to accurately diagnose the system, consider getting Hands-On Assistance from a highly qualified technician.

Oil is not something "optional".

[mr.coon]

So, i replaced the water filter yesterday and siphoned off the bottom 1/3 of the fuel tank when i got home from work. i turned the key and the engine fired up with no beeping! one problem though, there was no beep when i turned the key to the on position. all the connections on the motor were tight so i check my key ignition and the wires were frayed, loose, and there was mud all over them. this triggered the memory that i had to wipe muddy paw prints off my seat and console before i took the boat out! something got in there and messed up the wires. when i get home today, i will fix the wiring as i didn't have time last night. i am hoping this was the issue all along. also, i spoke to my mechanic. when i took the boat in to him a couple of years a ago, he replaced the oil pump and pump drive gear. it is the metal one in there. not plastic. i have only used the boat a dozen or so times since then.

Could the wiring being messed up on the key cause a false alarm?

[EuropeanAM]

Depends on where/what was messed up. Address that first, as it's an obvious problem.

[mr.coon]

Fixed the wires, beeping is back.

[EuropeanAM]

Four Beeps, Fast Beeping, or SOLID tone?

Also under what EXACT conditions?

[mr.coon]

fast beeping and only when the engine is running.

when i run it on the muffs it pisses when it warms up and give off a good bit of smoke out the prop.

[JOE54]

yes sir that's the way warning sytem operates , have you verified oil pump is turning and or crank gear is not stripped= post no. 2 if not gota do it to determine if cause is electrical or mechanical,,, git - er--- dun

[mr.coon]

So yesterday i did the oil pump drip test and it is definitely pumping as i got a steady drip. I checked for continuity in the motor mounted oil tank cap and it was correct (replaced it last year with a new one). i could't do the coil pack test because i scrambled the brains in my digital multi meter. just so everyone knows. don't leave your DMM in the bottom cowl and crank the motor, LOL. i changed out the pump motion sensor and that didn't work. So i guess i am left with either a bad oil warning module or bad coil. I will report back when i finally figure it out.

[EuropeanAM]

Did you verify spark on all six cylinders (loss of spark is one potential cause), and when you changed out the rotation sensor did you ALSO change out the bushing/magnet (there's a good reason why they include a new one in the bag with the rotation sensor).

[Hez]

[mr.coon]

Did you verify spark on all six cylinders (loss of spark is one potential cause), and when you changed out the rotation sensor did you ALSO change out the bushing/magnet (there's a good reason why they include a new one in the bag with the rotation sensor).

No to both of those. I will try over the weekend. The motor sounded great and ran really strong when I took it out. Could there be a spark problem even though it ran well?

[EuropeanAM]

Either of those items are possible (and keep in mind that "spark problem" is more specifically that the warning module is not receiving an appropriate voltage on it's RPM reference wire.

[mr.coon]

So, here is a late update. Took boat the the shop and they couldn't fix it. The mechanic said that this wasn't the first time he has seen this issue. Fished the rest of 2019 and 2020 with the oil module disconnected.

2021 - Three weeks ago I was running across the lake and a rattling sound started in the motor and I had to idle back. I lost cylinder #3 due to mechanical failure. The head is off for a rebuild. My mechanic and the shop that does the rebuilds are highly recommending deleting the oil injection system. I am tired of fighting the beep, so I told them to go ahead and delete it. Problem solved I guess.

[JOE54]

deleting oil inj because a bad warning module the most common cause of warning horn sounding or not sounding on this engine ,red led on small module is for water in fuel indicator also ,id fix it,just way i am though

[EuropeanAM]

Same here... far too many times these engines end up premixed because someone doesn't understand the system, how to repair it, or how to maintain it properly.

[mr.coon]

deleting oil inj because a bad warning module the most common cause of warning horn sounding or not sounding on this engine ,red led on small module is for water in fuel indicator also ,id fix it,just way i am though

The warning module was changed (part no. 4147A25). I am sure there was something in there they were missing, but I wasn't paying the labor for them to figure it out. I don't mind premixing. I grew up doing that.