engine beep than stalls

[nnoia05 0]

hello,

so bought my first centurion last year and had a great season with it, no problems, everything worked great. I put it into a nice heated storage building over the winter and now that summer is finally here, the boats broke! Been stalking the forum for some time without any luck so far, figured I would post on here, share some info and maybe it will help others in the future once I get my problem figured out.

 

The deal is, when cold boat starts right up, runs no problem at all. after about 6 minutes a single beep goes off, the engine surges about 2 or 3 times and it dies. it will start and run again no problem for about 2 minutes, than same thing. it will do this about 4 times and after that runs for only about 3 seconds and dies right away. Let it sit overnight and the process is exactly the same. I really think it is a temperature related problem. I purchased a scan tool for it to check for codes, only 4 codes set and they will not clear out, just come right back. code 75 fuel level 1 circuit high, code 119 steering position circuit low, code 104 lake/seawater temp circuit high, code 191 fuel level 2 circuit high. from what I understand all these codes are normal to be set due to the fact this engine does not have these sensors.

 

so it is not setting any codes that are related to the problem. also noticed with the scan tool when streaming data, when the engine beeps and begins to surge, the scan tool data values disappear, scan tool stays powered up, the paramaters stay there, but its like the screen freezes. eventually a loss of communication message appears. engine shuts down, and I can back out of the screen and go back into it and everything is fine. engine will start right back up without any problems until it happens again. also noticed with the scan tool a guardian mode parameter and a engine power displayed in percentage. both stay at a normal reading with power at 100%.

 

so far I have ruled out overheating, coolant temp doesn't go above 165. removed coolant hoses with engine running, plenty of water flow, also has a new impellar with stainless plate.

I did notice, port side exhaust manifold riser stays cold to the touch, starboard riser gets fairly hot, not burning your hand but very big temperature difference. don't think its an issue, was just wandering if this was normal

 

battery voltage with scan tool, gauge on dash, and checking voltage at both batteries with multimeter always shows above 13 volts with engine running. don't believe there is a battery or charging system problem.

 

playing with the lanyard does not seem to effect how long it runs, seems to run the same amount of time no matter what, goes through a similar cycle each time, almost like its more of a heat soak kind of problem. also the gauges do not loose power at any point so I don't think it could be an ignition switch problem either. the engine surges up and down and dies.

 

I really am leaning towards a faulty ecm, just seems like every single time the beeper goes off and it acts up, the computer goes haywire and bugs out.

 

my engine serial number is om395784 it is a 5.7 black scorpion.

the boat is a 2004 avalanche c4

 

I'm really hoping somebody else has ran into a similar situation and could help, but if not, at least I can add some knowledge to the forum and maybe someday help somebody else out

[Tommywalton1974 175]

It sounds like a bad sensor. Maybe oil pressure or coolant. I would, if I couldn't get it scanned, remove each sensor one at a time. Try to isolate it. My 07 Avy did this maybe 3 times while I owned it. Luckily it wasn't a constant thing.

 

The exact amount of time thing seems like a count down in the Ecm for one of these sensors. Does yours have that fuel cooler device on the starbord side along the bottom of the engine? Mine does and it has a sensor.

[nnoia05 0]

I was really leaning towards a sensor at first also. that was the reason I bought a scan tool for it. however all sensors seem to read normal, realistic things, not to say there couldn't be something weird happening, also there is no beep until it gets warmed up. seems like its not even hitting operating temp to go into closed loop. coolant temp never goes above 152, it gradually rises to that point like it should though. map reading is 3-4 psi at idle, when you crack the throttle it looses pressure momentarily than increases to around 12 psi which I believe seems normal. oil pressure is around 40 psi at all times. water pressure is 1.8 to 5 psi, depending on rpm. only strange one, spark advance jumps around a lot. it is at 3 than -7 than 12 than 3. it never stays steady. seems kind of odd to jump so much. was also wandering about my t-stat being stuck open, 152 seems cold and my heater never really seemed to pump a lot of heat unless the engine was around 2000 rpm or more. just always thought that's how it is though.

 

I stopped in at my local marina today, he is a merc dealer, says in the past 15 years or so with efi, hes only replaced two ecms ever. one worked but they wanted it replaced because it sunk. he told me these ecms are not like automotive style, they are extremely rugged and have a lot of fail safes built into them for protection. he is thinking a bad connection somewhere, bad ground, or possibly bad alternator leaking a/c voltage into the system causing ecm to shut down. all very plausible theories I think, will have to test them out tomorrow.

[Tommywalton1974 175]

You know I read a thread on here a while back. IAC valve can get dirt and cause a very similar issue. Have you googled that? It's under the intake cover of I remember correctly. A foam piece covered with carbon? Just can't remember.

[Tommywalton1974 175]

Also what type of scanner did you buy? I didn't know there was one available? Is it proprietary Mercury?

 

On the engine temp, mine quickly gets to around 185-190 and stays there no matter what type of load or water temp. If that helps you any. Mine is a 2008 Enzo with the same engine.

 

Water pressure? Had no idea it had a sensor for that.

[nnoia05 0]

checked on the iac motor today. no luck, i did find the filter that looks like its never been changed or cleaned or aynthing, but boat still has the same problem. even unplugged the iac, still acts the same. my thought with it being an idle problem, even if i hold the throttle open by hand, it still beeps, surges and dies. iac only maintanes airflow at idle.

 

yes there is a pressure sensor for the seawater pump. it is located on the trans cooler, just above the transmission. if the pressure gets to low a code sets and it goes into guardian mode to protect it, ask me how i know that one. had a seawater impeller with 30hours on it shred into pieces. no way I thought it could have been a bad impeller, I was wrong. I'm not sure what the range is for the sensor, what min or max pressure would be before it sets a code.

 

sounds like I do have a bad thermostat, going to have to change that one out.

 

I bought my scan tool off ebay, there are some merc specific scan tools available, for around $1500. this one was $680, came with all merc adapters. it also can plug into merc outboard. also with different adapters can plug into just about any towboat engine, indmar, pcm, even the new ford raptor engines. the scan tool is made by rinda.

 

tonight I think I'm going to try at the alternator and wiring connectors see if I cant find something ​

[Tommywalton1974 175]

I see. I read a bit last night. It appears you are in some sort or form of guardian mode. I saw a similar thread on some forum, I'm always reading.. And waiting for mine to start giving me issues. I did find a chart listing all the beeps and severity. Your issue seems to be of max severity. Which does narrow it down a little.

 

The thread was about a black Scorpion doing exactly what yours is doing. A seemingly knowledgable person replied it is a sensor, and there are only about 20 on our engine-drive.

 

you already know all that though I suspect, I'm going to keep following along and hope you get it sorted out.

 

Also i read where someone where ours has what's known as 555 Ecm? And it should only quit running as a result of just a few thing. All of which you have mentioned. Have you seen that Manual about the beep codes?

[nnoia05 0]

another update on the progress........ i ran it in the water, after 6 minutes it acts up again. tried to unplug the alternator with it running and just run it off the battery. it ran for about 15 minutes without any problem. took a voltage measurement, found 300 mv ac on the electrical system with alternator plugged in. unplugged it has 240 mv ac. i found a spec in the service manual about testing for ac voltage, says anything above 250 mv and the alternator has a diode breaking down and allowing too much ac voltage to pass. i've also noticed the lights in my gauges flicker pretty bad at idle.

 

i'm really hoping that im onto something here, i have an alternator ordered, just got to wait for it to come in.

 

also found out the price on the ecm, $1700 list price! really hoping its not that! he also says, there are only 3 ecms throught all of the us.

 

i have not ran across any chart for beep codes? that might be a good read

 

yes, as much as I have found, this is a 555ecm, but there is a ton of different part numbers for it. that happens to be the adapter for the scan tool that plugs into it.

[Tommywalton1974 175]

http://media.channelblade.com/EProWebsiteMedia/3506/Mercruiser%20warning%20horns.pdf

 

I think this is the link.

[nnoia05 0]

thanks for the link, good read.

 

got the alternator changed and went and ran the boat tonight. I ran it for 15 minutes on the trailer, than ran it down the river for about 40 minutes, everything seemed fine. no beeps, no hesitation, no problems. I didn't load it up or anything but it seemed to run really well. the real test will be this weekend we will see but I think I have it fixed!

 

only thing that concerns me, it didn't seem to change my ac voltage output. straight out of the back of the alternator I'm still measuring 300 mv ac, which according to the spec is too much. but so far no problems.

only other thing that I can think that would even create ac voltage would be my ignition coil, other than that I don't have any ideas where it might be coming from.

 

the most interesting part of this experience is that it doesn't set any codes at all, and the computer itself just shuts down. it doesn't register going into guardian mode, I even unplugged a sensor with it running, when it goes into guardian mode, the ecm still communicates and it sets a code right away. that's how I knew I wasn't dealing with a sensor problem. I have seen something like this once on a car. had a Pontiac g6 that would idle just fine, when you accelerate with it the rpm increase would increase alternator output to 16 volts causing the instrument cluster and abs modules to go into over-voltage protection mode. they never had any codes set for this and would do the same thing, just lose communication and black out. its like the people who engineered the computer and the people who engineered the software never talked to eachother about making a diagnostic strategy for this kind of event.

[Tommywalton1974 175]

Dude this is deep. I'm glad to hear it has changed and no issues yet. Must mean you were on to something. I wonder if the Ac voltage changed once the alternator warmed up and the batteries were topped off. If you get this figured out I swear you should write up something in the articles section.

[Tommywalton1974 175]

Also just throwing this out, my boat has 2 batteries with an oscillator. I've checked voltage at the batteries and while underway and I've never seen more than 13.1 most of the time around 12.4 and as soon as the key is off its below 12. 11.5

 

I have a digital gauge in my glove box hooked to the keyed 12v source. The voltage gauge on the dash never has got over 12v

 

All this seems very low to me and on the threshold of being an issue. I'm guessing the oscillator doesn't allow the 14v I have at the alternator to pass through. Strange.

[nnoia05 0]

that does sound strange. just curious what is the oscillator for? and where is it wired into the system at? my voltage at the battery and coming from the back of the alternator, with engine running is always above 13v. most of the time its between 13 and 14.

 

my boat has what I think is an automatic switch to charge the batteries. there is a red box in the engine compartment mounted beneath the ski pylon. the wire from the alternator goes directly too it. one wire goes to the second battery, the other wire runs to the starter and powers the engine harness. could your red box be going bad?

 

I was having issues with the gauges getting low voltage, even the volt gauge in the cluster, it would typically be 1.5 to 2 volts less than battery voltage. even measuring power at the fuse block was like this. when I would turn on the docking lights the voltage would drop so low alarms would go off, and everything in the cluster acted like it was about to die. one of my winter mods was to track that one down, I found that the main power feed wire for the fuse block underneath the steering wheel was a really small gauge wire, like 10 gauge or something. pretty small for powering all the boats accessories and instrument cluster. I cut that wire and ran a 4 gauge wire strait from the battery to the fuse block, than I attached the cut wire to that same terminal stud. the volt gauges read within .5 volt battery voltage now, no more low voltage alarms, seems to have fixed all those weird electrical gremlins I had also.

[Tommywalton1974 175]

That's the same box I'm talking about. It isolates my batteries. Reason I know it does is the stereo system battery went bad, would not play stereo until it ran a few min and still the boat would start fine. One battery does starting and one stereo, other functions. I'm sure Also I'm just not sure. Have you load tested both batteries? One could be shorted inside.

[nnoia05 0]

well took the boat out this past weekend, ran it 4 hours one day, six hours the next. no problems, never missed a beat. problem solved!

 

i load tested my batteries last year, i dont remembr what they tested, just that they passed the test. i dont ever have slow crank or low battery voltage. ever since i ran the larger wire to the fuse block my gauges havn't had any voltage issues anymore. they read almost right on with the battery.