Throwing a code, same rpm/speed, every time, like clockwork. Help on a holiday weekend

69fastback

i know there's a whole lot of different thing to cause the 2 beeps/minute alarm,  but maybe someone has seen something similar. My tach has decided to be erratic this year, so I can't give RPM specifics, but at exactly 35 MPH, I'll get the 2 beeps/minute, every single time like clockwork. I can slowly creep up to 35, or I can go WOT off idle, and at 35 MPH, I get the tone. The boat starts and runs great. It'll even accelerate up to its normal 55 mph speed with no issues, but the tone is there every time. I just drove it back to the marina at about 34 mph for about 10 miles, and no tone. 

I cant think of what it would be. All my temps and oil levels showed to be good. I can't imagine a sensor to make it go off at the exact same parameters every single time. I tried every marina to get someone to scan it, and they're all too busy. 


Thoughts?

212rowboat

throttle position sensor above or below will cause that- and it kinda makes sense with engine RPM being about the same at any given forward speed out of a current .... 

i think low is 4.8vdc and high is 5vdc- so the delta is tight. 

maybe hit the points with sandpaper or wire brush? make sure it's well seated?  

seawater pressure will also trip a 2bp/mn... and kinda makes sense as again- RPM to speed is about same... weird that 34 doesn't trip it.  stupid question, but does it continue to beep above 35?  that sensor could likely be recovered with a good cleaning, too.  

i'm thinking any of the other 2bp/mn alarms you'd notice, as they trip guardian and reduce power to 90%.  


edited to add: 

if you run it to 35 and get the alard trimmed up, trim or tab down if you have them (dropping speed by drag not throttle) and see if it remains... you can do the opposite too by approaching 34 or so tabs/trim down and lifting trim/tabs until you pass 35 and see if it alarms..... if it does this would all but eliminate the TPS. 

69fastback

Thanks for the input. 

Once it trips, I get the tone until I shut the engine off and restart it, regardless of speed. 


So, I don't have trim tabs, but I did donas you mentioned, and I took it to about 33-34 with the lower unit trim all the way down, and I trimmed it up tongain speed. It seemed to take a little longer, but it eventually gave me the tone. 

I also started off idle and went WOT, and with no trim adjustments off full down, it tripped as the boat accelerated through 35.

i do impeller replacements every other year, and last year was no replacement year, so the one in there has a full season on it. ~30 hours. 

69fastback

Ah, silly me. I forgot boat details. 

2003 232
350 MAG
Bravo 3

212rowboat

if you aren't having a cooling problem, it could just be the sensor- and the pressure sensor could be fouled..  i'm not read up on how they trigger, but it could be a thing that is programmed to be ignored until a certain engine speed or forward speed is achieved.

it's like most pressure sensors- has the hollow bodied threaded slug with the blank 'hole' in the end... could be it's obstructed... could be it's just flat not working.  ohm it out? 

69fastback

I can try to ohm it out. We are planning to spend the 7th-12th in the boat, on vacation. I hope I can get someone to give me 5 minutes of their time to scan the darn thing before then, if ohming it out doesn't reveal anything. 

212rowboat

for your engine, here are the possibilities of a 2bp/mn:

Two Alarm beeps every 60 seconds are for:
1.) Faulty cam, 
2.) IAC, 
3.) MAP, 
4.) MAT, 
5.) knock sensors. 
6.) open/short in the engine cooling temp circuit 
7.) open/short in fuel injector wiring circuit, 
8.) open/short in oil PSI circuit, 
9.) open/short in exhaust manifold cooling temp circuit, 
10.) open/short in sea pump circuit,
11.) open/short in throttle position circuit

i was wrong- the low pressure on your engine is constant beep.  

how old is your fuel?  is it recreational fuel or ethanol laded?

69fastback

Filled it up today....and I mean filled it. It was very empty and I put 65 gallons in it (75 capacity). E10 is what we are stuck with here, so that's what it is. Funny, as I was reading your post, my mind went to that. Bad gas? Could be, I suppose. The alarm started later in the day, so there was probably key at least an hour put on it before it went off. 

Cam sensor - I would think it would run poorly

IAC - don't think so. It starts, idles, and runs fine 

MAP- again, don't think so

MAT- ???? Stil, doesn't sound right

knock sensors - would that put it in limp mode?  It doesn't seem to be, but not real positive 



5-11 pfffff, I'm not sure what actual symptoms would be. 

212rowboat

the knock is what i was thinking... and that could be caused by advancing spark on inferior fuel, no?  i don't think it has to be a continuous knock, but just a single one at some point... but... i tend to agree with you. 

the IAC just had to be out of range at whatever engine speed- doesn't have to be idle, and the TB can hide a lot of issues with it during operation. 

69fastback

Knock could definitely be caused by inferior fuel, and I got it at a different station that I normally do because I went to a different lake. We burned a lot today, more than half, so I'll fill it with premium and try again, if I can't get it scanned. 

I suppose youre right about the IAC and TB. It just seem like the "normal issues" associated with them, but that definitely doesn't rule them out. 

69fastback

Thank you sir for the help. It's likely nothing detrimental. It's just annoying. I guess i
l need to make my radio louder in order to drown out the beeps. Lol

reneechris14

So those  kicker's are the fixers

69fastback

Another question. Since this boat is a '03 350 MAG, is it Smartcraft capable, or are all them not capable?  If I got vessel view on my phone, would it show the codes?

69fastback

Well, nevermind. It has the Smartcraft logo right there on top, so I guess that answers that question. I'm thinking that looking into vessel view mobile could be beneficial. It looks to be a cost of about $250????   I'm in, if that's the case. I just need to find a place to purchase it. 

Willhound

I'm not sure but if you send your engine serial number to Mercruiser support they will reply pretty quick. Found out my 2000 5.7 EFI is not..

Cableguy Greg

If it is Smartcraft, the VVM will show you the codes that the engine is throwing at you. Your boat is a 2003, so the engine is probably a 2002. Merc will be able to give you the final answer, or a Merc dealer.

69fastback

I would assume that since it has the smartcraft logo on it, that it's compatible. I called my local dealer, who is open today, and I'm waiting on them to return my call. 

69fastback

MarineMax has one in stock, so I'm on my way to pick it up. 

69fastback

Ok, so I'm looking for some insight here. I got the codes pulled with vesselview, and as I noted earlier, I would only get the 2 beeps above 35, but it threw all these codes at the same time????  What's happening here?

69fastback

This has to be some sort of voltage or ground issue. 

davidbrooks

Mercruisers throw "phantom" fault codes.  I have 5 that are constant on my engines. Pitot, Fuel Level, Steering position are all phantom.  The Sea Temp is indicative of a bad sensor.  This sensor is towards the back of the engine and easy to replace.  They go bad. Doesn't mean the boat is overheating just a bad sensor.  I would replace the sensor and see if the beeping goes away.  It is likely putting your boat into guardian mode even though it doesn't need to be.

69fastback

Thanks so much!  That makes sense. The boat doesn't seem to go into guardian, but still gives me a attempted fix. 

69fastback

So, is my analog water temp gauge in the boat still correct?  I was just running it on the muffs and the gauge and the temp on the app matched, so maybe it's intermittent?  Regardless, the analog gauge should still be correct?

davidbrooks

The water temp off the analog guage is likely fine and that is fed from a different temp sendor that is in the Tstat housing at the front of the engine. I didn't understand why there were two water temp sensors either.  My old boat had one go bad and it drove me nuts.

69fastback

I figured that was the case. I imagine with the sensor bad, I'll probably get slightly less fuel economy, since the computer isn't get correct information. I'm calling around to see if I can find one, as we are leaving for a 5 day lake trip early tomorrow morning, but at the end of the day, I can make it work like this, if needed. 

davidbrooks

Just reread the code.  The sensor i was referring to is the water pressure sensor.  Water temp sensor is on the front of the engine in the side of the thermostat housing.  Like was stated earlier it could be a bad wire going to the sensor but they are easy to swap out as a first step.  Tracing a bad wire is a nightmare sometimes.  I often just run new wires.

Cableguy Greg

You can silence the Pitot, trim and the tank sensor. You don't have anything connected to them. The sea water temp one is legit.

69fastback

davidbrooks said:

Just reread the code.  The sensor i was referring to is the water pressure sensor.  Water temp sensor is on the front of the engine in the side of the thermostat housing.  Like was stated earlier it could be a bad wire going to the sensor but they are easy to swap out as a first step.  Tracing a bad wire is a nightmare sometimes.  I often just run new wires.


Cool. I'll find it. 

69fastback

Cableguy Greg said:

You can silence the Pitot, trim and the tank sensor. You don't have anything connected to them. The sea water temp one is legit.

Yes sir. I just blocked those.