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moptop121
11-10-2005, 07:55 AM
2005 new 18 classic 350 Mpi
A constant horn when running full throttle, Horn shuts off when throttle is reduced. Water press,water temp, oil press are all in limits.
Any body had this problem.
moptop121

Trueser
11-10-2005, 08:04 AM
How many RPM'S are you running? Possibly the rev limiter warning.

txtaz
11-10-2005, 08:06 AM
The early warning horn is triggered by sensors for hight water temp, low engine oil pressure and low drive resevoir oil level. Check the drive oil level.
Da Taz

Barry Phillips
11-10-2005, 09:39 AM
I have the same problem on my 22 equipped with a 496 Mag / 23” Mirage Plus. The problem is the 23” wheel is not enough prop for my big block. My tack shows 5,000 rpm and my horn goses off under the most optimal conditions, cool temps, light chop and light load at a neutral trim level. I used to own an 18 running 350, 250HP, Bravo 1, spinning a 23” Vengeance. The boat could run 66mph at 4,800 under the best conditions. Your 350 Mag should be turning 5,000 at WOT. What size is your prop? I would guess it’s a 23” Mirage Plus, if it’s a 21” try a 23”, if it’s a 23” try a 25”.

Dave_N
11-10-2005, 10:12 AM
You will get an alarm when you hit the rev limit. You may want to have someone with a scan tool check the fault history to be sure thats what is happening.

Dave

Kirbyvv
11-10-2005, 11:13 AM
I had this happen twice this past summer, once on our Celebrity w/ 4.3 and once on the little Pro Line outboard (50 hp merc). Both were a pre-cursor to the water pumps going.

Barry Phillips
11-10-2005, 12:16 PM
Dave N, been there done that, I had a scan tool put on the motor and the boat was in water tested just before lay-up. I was told that the Guardian system since my 496 is not equipped with Smart Guard is designed to reduce power buy 10% when it hits the rev-limiter. The scan tool did not find any other problems. The mechanic was also surprised there would be a rev-limiter warning also, but that is his assumption. Once again my horn sounds off in the most optimal conditions, when I really flying the boat. I’m going to try a 25” Mirage Plus in the spring and see what gives. I did not hear this warning all summer yet it sounds off when the temp drops in the low 70s. My gauges are within normal limits, if it were low water pressure problem the motor run hotter, temp never changes. I met up with a guy on LG with a re-powered St. Tropez running a brand new 350Mag and mentioned he was having the same problem at high speed. Mecruiser’s phone rep. has been pretty uniformed on this problem suggesting a faulty sensor. Any advice is appreciated.

BP

gold-n-rod
11-10-2005, 01:15 PM
How does one test the warning horn? On my Mach, if the key is left on without the engine running, it will sound after about 5 seconds.

On my 5.0 mpi, there's no such sound, and I've intentionally left the key on to see if the alarm would sound.

Different systems???

Dave_N
11-10-2005, 01:32 PM
Barry,
I don't understand why there is still confusion about the cause of the alarm. The tech should have been able to identify the cause and not just "assume" it was an overspeed fault.

Dave

Barry Phillips
11-10-2005, 03:22 PM
Gold-N-Rod, on my 22 the warning horn will sound in the key on position and than turn off in the run position, hopefully this is only time it should be heard if every thing is working well.

Dave, the tech is convinced that the boat is under proped, yet people are telling me that rev-limiter dose not engage the warning system, the Mecruiser phone rep. was not even sure what the horn warnings indicate. Even my manual dose not seem have a lot of answers. Although my motor is Smart Craft compatible it dose not actually have Smart Craft, which is merely a gauge package. There is a little sticker under my helm, which indicates that Smart Craft warns of low oil pressure, overheating and low drive fluid. After a WOT run this past October triggered the warning as soon I reached a trim level just above neutral position on the gauge and dose not go off until I shut down, which seems to reset it. I check the oil every time I go out, the motor was not over heating, I could touch the oil on the dipstick as well as hold my hand on the exhaust risers, which were warm as they should be. I even lifted out the drive overflow tank to check for a pinched line. What I did notice was the drive oil was full to the cap, since I usually check it cool, I do not know if this means anything. It’s hard for me to except that it is merely an RPM issue also.

BP

SenorAnaconda
11-10-2005, 06:29 PM
We had a boat with a similar problem, the oil pressure sensor had a very small leak. It would cause the alarm to sound at high RPM's (higher pressure) and would go away when the RPM's dropped (lower pressure). The oil pressure gauge was not affected as it is reading from a different sendor. We replaced the sensor and it corrected the problem. It's worth a shot.

moptop121
11-11-2005, 07:53 AM
Oil pressure,water temp, water pressure,Drive oil are all in limits.
engine rpm 4800,Speedo leaking water cannot get true reading.
The boat is at A mercury service center, awaiting the correct harness for the analyizer.
Will post the results. Thanks again ALL moptop121

Barry Phillips
11-11-2005, 08:35 AM
Keep us posted on the results of the harness replacement. Your 350 Mag can turn 5,000 RPM without issue. I'm still curious what size prop your running, it's stamped on the prop. My 18 did not have a Mag, it was equipped with a with a what Mec. called a 5.7L, which made 250HP, with the 23" Vengence at 65 mph confirmed by radar at 4,800 rpm was fairly impressive.

Thanks
BP

moptop121
11-15-2005, 05:06 AM
2005 18 ft classic
350 Mag MPI
25 pitch Mirage 4400 rpm WOT
The analyzer showed no faults so the mech took the boat to the lake.
He incountered the same problems.He thinks the nock sensor is limiting the rpm and or telling the warning system to reduce power. Next step call the Merc Rep.
Will keep you posted on new results.
moptop121

moptop121
11-15-2005, 06:42 AM
Yes it is but
It came with the boat. We will have to go thru all the proper channels to get the right one thru warranty. Even the tech thinks it is to much. We are waiting on Mercury to make the next move.
moptop121;)

Woodsy
11-15-2005, 06:57 AM
Moptop....

Before you change your prop, check the gear ratio of the drive. If the drive is a 1.65:1 ratio, then you have the correct prop. If you have a 1.5:1 drive then you need a 23P Mirage+.

Woodsy

LKSD
11-15-2005, 07:25 AM
My 18 (1999) 350 MPI MAG 1.65 IS RUNNING A 25P BALLISTIC @ 4800 RPM & 68-72 MPH DEPENDING ON WATER CONDITIONS.. I AGREE IF THE DRIVE IS A 1.5 THEN 23P..

LKSD
11-15-2005, 07:33 AM
Just out of curiosity what grade fuel are you running? the lower the grade the more likely detonation may occurr this will trigger the knock sensor, especially if its a bit screwed up.. I dont know if you added a SC, but you may also wnt to check / watch your map sensor anyway, especially if you put a SC on the engine. If you did sc the engine, Sc additions must have a psi bypass for the map, otherwise they will trip the buzzer under boost.. J

txtaz
11-15-2005, 08:08 AM
Yup, Check the ratio. I tried a 25 on a 1.5 Bravo and the best I got was 4600 rpms (350 Mag) and it was sluggish coming on plan. The 23 Mirage + is sooooo much sweeter.
Da Taz<<<Who will need a 27 or 29 in the future....Hear that DonCig...:biggrin:

Barry Phillips
11-15-2005, 08:41 AM
You 350 mag seems under proped to me, 4,400 rpm is not were you want to be. As I mentioned before you should be turning 4,800 to 5,000 rpm and this can be achieved with a 23" wheel or have your 25 labed. A good running 18 running a 350 Mag should be at least in the 68+ mph range. I wish you and I could meet up and just switch props and just see what happens. Keeps us posted on you your alarm problem, it's not being caused by your rev limiter, not turning 4,400 rpm.

David Hartmann
11-15-2005, 02:17 PM
Warning horn
I have had this go off for unexplained reason when I am really blasting along. i would start when the water was rough and I was running at about 4500. Stupid of me but it turned out that the oil level was a little low. I think all the moving around made the engine starve for a bit and then it had low oil pressure on the alarm even the the gauge never showed a problem.

Prop / speed
I run a 21" mirage it gets up around 4800 before I stop lifting the trim at full throttle. That runs a GPS 63.0 MPH This is on a 19' St Tropex ( a very Heavy Donzi) your 18 should be good for 70 and should be able to turn a 23 or 24 inch prop. Tabs are going to be required unless you are mental. My boat gets scary at 63mph tabs will be on it for the spring and I think I can take to 65mph. Iwill also change to a 22" 4 blade

Barry Phillips
11-15-2005, 03:14 PM
Hi David, I heard a very similar account from a guy who owns a with a nicely restored 67 St Tropez running a brand new 350 Mag. I was running my 22 on LG NY, in October and he right along side of me. Nudging 65mph in moderate lake chop and I was dam impressed with how well this hull ran. He also mentioned the boat he was a little scary at high speed without tabs as well as the warning horn problem. From my point of view the boat did not look scary at all, it ran clean and level with a little air every now and again with nice reentries. The St Tropez has a fairly flared forward gunnels for spray control, a feature that will make it leave the water at high speed, but he looked perfectly in control and I was in impressed.

BP

joseph m. hahnl
11-15-2005, 03:40 PM
Hi David, I heard a very similar account from a guy who owns a with a nicely restored 67 St Tropez running a brand new 350 Mag.

Barry: That was probably David Hartman. He practically lives on LG. I had the destinc pleasure of meeting him also. HI DAVE:wavey:


joe

David Hartmann
11-15-2005, 04:49 PM
Hi David, I heard a very similar account from a guy who owns a with a nicely restored 67 St Tropez running a brand new 350 Mag. I was running my 22 on LG NY, in October and he right along side of me. Nudging 65mph in moderate lake chop and I was dam impressed with how well this hull ran. He also mentioned the boat he was a little scary at high speed without tabs as well as the warning horn problem. From my point of view the boat did not look scary at all, it ran clean and level with a little air every now and again with nice reentries. The St Tropez has a fairly flared forward gunnels for spray control, a feature that will make it leave the water at high speed, but he looked perfectly in control and I was in impressed.
BP

If it was a St. Tropez on LG then it was most likly me. And if I get a chance to run along side of another Donzi, I always do.

Everyone tells me tabs will solve all my problems. I am planning on finishing the topside cosmetics this winter. I will do the tabs and steering in the spring.

Nice to see both of you online.

txtaz
11-16-2005, 08:28 AM
I hardly ever use tabs on my 18 anymore, only to balance load. At WOT I have them all the way up. I don't think a tab should be the first thing to hit after a jump. If the boat was a little crossed, it would accentuate the counter effect when coming down.
Da Taz<<<---With a pilots license

gold-n-rod
11-16-2005, 08:34 AM
I hardly ever use tabs on my 18 anymore, only to balance load. At WOT I have them all the way up. I don't think a tab should be the first thing to hit after a jump. If the boat was a little crossed, it would accentuate the counter effect when coming down.
Da Taz<<<---With a pilots license

I've found that the more I use my 16, the less I use the tabs. Must be the "pair" grow with practice!!!!!!!!!!!!! :eek!:

David Hartmann
11-16-2005, 02:47 PM
You say you don't use them any more.

Have either of you verified that the tabs are not touching the water when all the way up. It would seem to me like even if the tabs were mounted an inch high and fully retracted. The trailing edge would be touching the water. That is all it would take to prevent chine walking.

Did the boat always have tabs our have you experianced it with and without.

I am really tring to figure out what to do here. Any information would be helpful
Thanks

txtaz
11-16-2005, 03:27 PM
David,
I don’t have the boat here to measure but I do know they retract enough to where they would not touch the water at all at speed. My boat has always had tabs and when I was first learning to drive it they were very helpful. After a 100 hours of seat time I got to know the boat well enough not to need them except to level it based on load and cruising speed.
I have a set of Victory tabs I’m putting on this winter. If you would like, you can have my old ones (Bennets I think) for a very reasonable price. You will only need the actuators and pump to make them work.
Da Taz<<---I have Victories...Hey Don, Do you have Victories???

moptop121
11-17-2005, 05:15 AM
Thanks All
You have been very helpful.
18 CL 350 mag mpi,( warning horn at wot)
eingine oil level---ok
drive oil----------ok
Running premium grade fuel.
Still waiting on the local Mercury rep for help

txtaz
11-17-2005, 08:46 AM
moptop, I looked for the schematic for your system but it was not in the Mercruiser manual. I think it's in the Seloc manual that I used to have and gave away. Maybe someone can post it for you.
Da Taz<<<---One manual short of a cherry pie

Dave_N
11-17-2005, 09:19 AM
moptop,
Maybe I missed something here, but I still don't know why your mechanic is not able to diagnose the WOT alarm :confused: . The freezframe history and fault history should tell him exactly what is going on.
If you are getting an overspeed alarm at around 4600 RPM, then it is running at 90% Available Power (the rev limit is reduced as Available Power is reduced). There are many faults that can cause a reduction to 90% Available Power, but they should also be triggering an alarm ("soft" alarm-two beeps per minute). The only thing that I know of that can cause a reduction to 90% Avaiable Power and not cause an alarm is bad shift position sensor (the ECM thinks the engine is in neutral). Just a thought.
Dave

txtaz
11-17-2005, 11:08 AM
Dave,
None of my early warnings were registered in the ECM. Everything was code 12. I think they are two seperate systems.
Hey Richard, Can I borrow my book back sometime?
Da Taz

Dave_N
11-17-2005, 11:58 AM
Wes,
What was the cause/solution of your alarm issue?

I believe your engine uses a MEFI 2 system. The ECM555 diagnostic system used now has the ability to generate and store a snapshot of engine data when a fault code is triggered, and record the number of seconds the condition existed. Previous MEFI generations were not able to do this at all.

With the ECM/PCM555 system, you can observe the engine run time and number of occurrances for each fault, and you should be able to answer any question as to what the cause of an alarm event is/was. Why this could not be done in this case is what I don't get. Wish I could see the engine data.

Dave