Mystery Alarm

[81merc]

Hi All,

Posting here since its seems to be a motor issue / alarm.

Got a new toy over the last weekend. A 1999 SeaRay F16 XR jet boat with the 175 sport jet motor in it. I took it for a short test ride and it ran great. Quick push from idle to near full throttle had no bogging down, quick push from near full throttle to idle, no stalling or sputtering. did it cold and warmed up both, no issues. It drove smooth and responded well turning (it will take a bit to get used to a 1/2 turn of the wheel and BAM you're going the other way.... Boat and hull are over all seem in great shape seems to need very little, just some clean up and a new name decal.

However after running around a little bit an alarm started to beep on and off. nothing seemed over hot or too much water in the hull. The gas level was very low, will that alarm? The Previous owner said its because the key is getting turned a little and you just need to turn it back a little bit. The seller was a nice old man so had to believe him and I'd check it out next time in the water. plus at any rate with how good it was running I wasn't thinking it could be too major. Does this make any sense to the pros on here? Ever heard of this? If not what else would you check?

Then the other day I got it out on the water, full gas, full battery charge and still alarmed. I did mess with the key but no changes, for sure didn't seem to be related to the key. There's not much of a pattern to the alarms, 3 beeps, 6 beeps... I did notice that it was not going off when running full speed, or running around 15 or 20. Seemed to be most common when running under 15 mph or when coming off plane. Seemed to be somehow related to change in rpm or angle of boat in water. I could not find a consistent RPM it always started at nor stopped at.

Anyone have any idea to trouble shoot these alarms on this engine / boat? Things to try and figure out more precisely how to trigger it more consistently?

Thanks,
Doug

 

[BTL]

I'm curious to see the responses to this question. My friend has a Merc 225 that gives a mystery alarm when he's idling, and no mechanic has been able to pinpoint it yet. Just one beep though.

 

[alldodge]

How is the oil injection tank level?

 

[racerone]

Some of these V-6 motors have an alarm that senses " no rotation " of the oil pump.

 

[81merc]

I just double checked the upper tank is tip top full, the reserve tank is about half full. Also the lower tank has no sensor or type of wire coming from it.

I had read something about this engine in certain years used a plastic oil pump gear that was known for slipping. That's what I really get the feeling this is, a non-persistent alarm, something getting slowed / plugged and then freeing back up. or faulty sensor somewhere.

Does this motor monitor water flow or just engine heat? One of the things I thought it might be is at certain times the pump
stops pushing enough water through and it alarms, the change is speed / tilt gets water flowing again.

 

[alldodge]

Manual states if you hear beep, beep beep then there is something wrong with the oil injection system and needs to be checked (page 123)

http://162.144.28.33/lib/mercury/man...tjet.html#/122

Have a look at this link and as you go thru it shows how it works and how to test and adjust

 

[81merc]

That's a great reference. Need to finish going through it but pretty sure that's the alarm I hear (same as when keys turns on).

 

[81merc]

Well the link leaves it at pretty much 1 of 2 things 1) oil pump not spinning 2) low oil in upper reservoir. a third is a bad tks ecm but that seems less likely.

Nothing seems to measure flow rates, just is or is not spinning and from the looks of things there really isn't a sometimes does / sometimes doesn't spin for the pump. So if its the pump sensor I'd lean more towards the idea of it being the sensor itself not the pump. tis one puts out a specific voltage range so no voltage (un-plugging sensor) or too much voltage would trigger it.

The link also says that the alarm for the upper reservoir sounds when the tank is not completely full, the idea being you have 30 minutes of run time to get in after it goes off. I went back out to the boat and looked things over again paying more direct attention to the upper reservoir I'm noticing that there is some fair oil leakage down the front part of the motor and along the lines to the pump. These leaks make me feel like its very possible for the level to fall slightly below full at times.

The test I think would be pretty easy - if the float is all of the way up there should be no continuity though the sensor so I should be able to unplug one of the sensor wires and re-test since it only takes 5 minutes of running to trigger the alarm. I suppose the other option would be to zip tie up the float if I have to.

 

[alldodge]

seller was a nice old man so had to believe him

Its a shame you cannot trust anyone anymore. I'm sure he knew what was wrong and I'm guessing its the pump. Things are easy enough to fix if you can get at the things. Those oil tanks develop cracks quite often over time. There is a possibility you could disable and remove the oil tank and just pre-mix the oil and gas. Folks without many of the OB do it often.

In any case your narrowing it down

 

[81merc]

hey alldodge, you really can't... I did call the guy today to see if I could contact whoever worked on it to get service records, turns out a couple years back he switched from a marina to a "local mechanic" so the most recent work isn't really recorded. Also got more detail on this "turn the key back a little bit" idea, really was turn it back far enough to turn off the aux power, which turns off the alarm. he was told to do this by the local mechanic because "its just a false alarm".... UGGHHH. It might not be the guys is wrong, but still fix the fault in the alarm system don't just turn it off!!

So I thought most 2-cycles when they get run without oil mix even for a few minutes rev really high and if not oil supply restored they will overheat or burn out pretty quick? how would I know if the motor is or has been running without the right amount of oil? I would think if the oil pump is stopping and oil flow stops that the engine would start getting choppy and/or stall out. when this alarm sounds there is no change in engine sound at all, if it wasn't for the alarm itself there would be no reason to be suspicious based on the way it runs and sounds. I am thinking about mixing some oil in the gas anyway just to be save while I work through the issue, would rather be running rich then lean.

I still need to get it on the water to disconnect / zip tie the oil reservoir level sensor, might not be it but seems easy to eliminate that pretty quick one way or the other. but got held up with the trailer bearings. pulled them apart they are shot on both sides. Whatever idiot last did the bearings put a seal in that is at last 3/8 of an inch bigger then the spindle so the grease that was in the hub was well watered down. The rollers are just barely still hanging in the bearings.... Going to get parts tonight to get it wrapped up and back on the tires.

 

[alldodge]

So I thought most 2-cycles when they get run without oil mix even for a few minutes rev really high and if not oil supply restored they will overheat or burn out pretty quick? how would I know if the motor is or has been running without the right amount of oil?

Agree, if they run without oil the rpms go up and then the motor burns out. The motor needs oil either injected or in the gas mixed. They started using oil injection to use less oil and clean up the environment. If oil injection works correctly its great, but when it fails its costly.

I was just saying others with OB and watercraft have disabled the oil injection and just started adding oil to the gas at 50:1 ratio. Main issue is figuring out what to do to fix what you have or fix so you can premix

 

[81merc]

Agreed, if this thing turns out to be an expensive fix that's exactly what I'm going to do.

When I was talking to the parts guy at the marina picking up bearings, seals, spindle sleeve, he said sounds like it could be that reservoir oil cap. he said the floats in those over the years absorb oil and become less buoyant thus set off the alarm. They had one in stock so I grabbed it. I got the bearings put back together tonight so will put it in the water in the morning and either eliminate or identify the oil reservoir cap, hopefully just by disconnecting or zip tying the existing one and if it is that I'll have the part right there to replace it and put this to rest.

 

[81merc]

Well its certainly getting oil... I mixed in about 1/3 of a gallon into the 20ish gallons of fuel in the tank just to make sure and its got quite the smoke cloud right now ....

I put it in the water, tired in-plugging the oil cap wire, no change, unplugged the blue wire on the motion sensor, no change, plugged those back in and tried to zip tie the float up in the reservoir tank and it seemed "better", but still alarmed the difference was now it only seemed to be going off at idle. so today I put it on the hose to see if it would alarm at idle and it does, and does so more consistent. It beeps 4 beeps then stops for a bit then 4 more beeps. The time in between didn't seem very consistent but when there was 1 there was 4. I removed that oil cap and turned it upside down (so the float has to be up) and it still did 4 beeps immediately when I started it, but didn't seem to go off after that.... it was getting late so I'll have to validate my results tomorrow but maybe I'm getting somewhere???

 

[81merc]

Broke out the multimeter today and started working through it. The oil cap / sensor is fine, hooked up the meter put it in and out of the tank it when on/off exactly like it supposed to.

So on to next check - oil injection sensor. I checked voltage on white lead going. Assuming this is feeding power to the sensor, and getting very erratic voltage. with out the engine running it reads 0. fire up the engine and I'm seeing anything from 1 or 2 up to 20+ volts. plugged white wire back in and Checked the blue wire from the sensor and it was very erratic as well, less then one, over 10... granted I didn't do the "turn it over with pull cord" exactly as described, and not sure why the white lead was 0 without the engine running, the steps in the book (image attached) don't say to start or turn over the engine to get the 12V reading.....

 

[81merc]

Well tried the 'turn it over by rope but really didn't work well (rope was to big, will try again later). Did confirm a couple oddities - after turning off engine the white lead went right to steady 12v for a few seconds then slowly to zero. Also when running engine above idle the voltage was much steadier, not +/- 1V from 12V but at least not 1/20/1/.3/27.....

That last clue kinda of tells me when the voltage regulator is not getting slammed / shorted it can dole out even. I think next thing to check is power feeding the system (stators?).

I tried to watch the meter / listen if there was constancy with voltage spike / drop to see if the alarm matched it but with delays between the two I didn't really match it up.

 

[alldodge]

From what I read in your post you didn't test according to the test procedure. These test are done with the motor off, plugs out and wires grounded. Does appear to be working though

 

[81merc]

Yeah agreed. First thing I did was check the white wire with just the key on but didn't have any current. I wasn't sure if the text at the top was a warning or direction. Because step one doesn't say to turn on the key or even turn over the motor, with starter or cord, then if you look down at step 3 it walks you through actually pulling the plugs, grounding the plug wires then pulling the cord to turn the motor over.

http://162.144.28.33/lib/mercury/manuals/175xr_sportjet.html#/134

Question - when it says grounding the spark leads does this just mean to put a wire in the boot connected to ground, or make sure they are protected from get grounded, thus sparking.

 

[81merc]

Well love inconsistency in the documentation. See the screen clips from page 66 and page 127. #9 on page 127 is supposed to be the same as the "TKS ECM" on page 66 (note the missing green wire...)

 

[alldodge]

Grounding plug wires means to remove wires from the plugs and ground them to the block or other ground. Many water craft have metal prongs sticking up somewhere that the wires go on

Most manuals do have things that were missed and later revisions get fixed.

 

[81merc]

No prongs or ground posts that I can see. I can get them grounded, it just might look ghetto. Do you think the grounding them important for the elec. output readings or just to keep it from starting?

The first test in the motion sensor section is to trace a green wire from one of the coil wires from the ignition switch boxes to the ECM, but I don't see any wire in the boat running from a coil wire to the ECM. so I have no idea what I should be testing here next. I get the feeling the voltage coming from the ECM (white wire) is off so I want to verify if the power goin in is as wrong.

Of course that's all based on the assumption that testing done thus far is valid. I suppose later today I'll do the pull plugs (might as well replace), ground the plug wires and pull it over by hand to verify the outputs, if that's right then I don't have to keep tracing backwards and non of that matters.