496 Water Pressure fault? Or??? HELP!
 

Just started up the Velocity today for the first time with the Smartcraft hooked up. I immediately got an engine alarm on the display. (It is a System monitor). The only thing I could see that may be wrong is the water pump pressure. It is around 2.2 - 2.5 at idle. Is the error code coming from my computer or could it be stroed on the System Monitor from the last boat it was on (use Monitor). The gauges and rest of the Smartcraft display look goo. 160 degrees, 40 psi for oil, perfect idle at 640. I am NOT getting a Low Water Pressure alarm though...... Any ideas on where to start?

What is the acceptable ranges for raw water psi for the computer? Anything else I can check? Any way I can clear all codes with just the System Monitor?

:poopoo:

You cann't clear codes with system monitor need to hook engine to scan tool and check it out,water psi at 2-2.D5 at idle seems low alot of times the psi sender gets clogged the 496 will also go into guardian with low water alarm will start beeping and engine will be limited to around 4000,if you cannot find anyone in your area i am not too far from you and can scan the ecm for you and get you going Dave 443-223-6876 MDG Performance Marine

JUst clear the fault code and see what comes back on restart. 2.0 to 2.5 psi at idle is just slightly low for a strong raw water pump but sometimes the error factor in the sensor and slightly low water pressure at idle are not an issue especially if it comes up quickly at higher rpms.

Depending on when the last time you serviced the impellor and how grooved the end plates on the raw water pump are you can loose pressure pretty easily. You can depending on access sometimes just remove the rear cover only from the pump and give the impellor a look see. If the impellor is old and needs replacing anyway them if the end plates are not badly grooved or such just pop in a new one and recheck the pressure. If the end plates are grooved, then just buy the new stainless replacement pump kit from CP Performance and don't invest or use the Mercury overpriced weak pump anyway.
Remember, If it ain't broke, don't fix it!

Best Regards,
Ray @ Raylar

Thanks for the inputs guys. I am having it scanned next week by a local group. If it is a water pump issue, I am not even going to try changing the impeller. Just going to go with the stainless unit.

Hooked up the alarm behind the dash and it goes off as soon as power is applied to the system. I think I have a sensor stuck closed perhaps. Where and which sensors are monitored by the audible alarm? If I remember correctly, it is water temp, oil pressure and outdrive fluid level....

i did the stainless replacement over the winter and they are very nice

Had the scanner hooked up yesterday. It was the Mercrusier laptop setup from a local Mercruiser certified marina (I do not believe it was Diacom, but very similar). It would not connect. The flashing light on the interface box kept blinking and it never saw the connection. He was not able to connect to my wireless system at home to re-verify his identity either... Hmmmmm.....

I broke the wiring schematics out on the diagnostic plug. I noted that the outside two wires were the +/- 12 volts, and the center two were data line. I had 14 volts on the outside wires, and saw appx 5 volts on the inside data lines. My PCM555 is putting something out.... Why wouldn't it connect? He said it was working before he got there that same day, and just inoformed me it was working back at the shop today..... Hmmmmmm....

If you can't re-verify your ID on the Mercruiser SW, will it kill the connection? If I had a wiring issue, I would imagine I would not be getting either voltage or data on the diagnostic plug, but I seem to be...... I know the computer is not bad. Starts and runs fine, and gives good indications on the Smartcraft monitor (except the fault indications that is).

Anyone know where to go from here?

Thanks!

He finally was able to connect. No alarms were present except the fuel levels, pitot, steering and trim alarms. The only issues in the freeze frame were a crank sensor and a TPS issue (from when I unplugged it yesterday). Otherwise it was very clean. Crank issue was at 159 hours and apparently repaired. That was the only "Guardian Mode" incident and took place at appx 20% power and coolant temp of 193..

Here are the run times. I think these are pretty decent for a 9-10 year old motor (271 hours)
0-750 RPM 60 hours
750-1500 81.6 hours
1500-3000 53.2 hours
3000-3500 45.7 hours
3500-4000 22.6 hours
4000-5000 6.7 hours
>5000 .3 hours (18 minutes)

No hits on the knock sensor in the history. No other faults or codes.....


So why do I still have faults on the Smartcraft System Monitor?

The pitot alarm is always on and cannot be cleared. If you don't want this to show up (assuming you do not have a pitot connected) select gps speed on the options or setup menu and it will turn off the pitot indicator.

Dan

I can't. Not with a System Monitor.

Learn something new every day. I am using a Mercmonitor so I suppose that they are different.

Dan

Clarification questions?
 

Redhook98:

It seems from your original post that the only indicator of a problem is on a recently installed Smartcraft system monitor and the indicator is low water pressure at idle of 2.0-2.2psi or there abouts. That is a slightly low water pressure and its possible that the Smartcraft monitor has a higher low water pressure trip point than the stock engine ECM as programmed. Try disconnecting the Smartcraft monitor and see if the regular low water pressure fault beeps show up on the boats dash beeper alarm with this same low water pressure. You went to all the trouble to get a scanner readout, WHAT WAS THE WATER PRESSURE RECORDED BY THE SCANNER ON THIS LATEST CONNECTION?!! That was the problem was you were indicating but your most recent posts don't give that information? I hope the person doing the scan read out that pressure and you have that number.

We seem to be getting possibly a little to complicated here for your own good. Before you installed the Smatcraft monitor system did you get any alarm beep at the dash after the engine was running? If not then I would suspect something is either wrong with the Smartcraft monitor system or possible connections as it should not show a low water pressure fault when the engine is running. It could show a low water pressure fault if the engine is key on only and not running because it is not seeing correct water pressure then. I guess we need to reconfirm here, did the Smartcraft system alarm for low water pressure show up when the boat is in the water idling after startup? or just when its either key on only or idling on a hose connection to the drive muff?

All the other scan data and events look like correct data and outputs so it seems from what you are saying that only a low water pressure indication on the Smartcraft ONLY system is the issue , correct?

Best Regards,
Ray @ Raylar

I apologize if I am all over the place on this. here is the story..... When I bought the boat, I had only heard it run and saw the gauges. All looked good and i was getting it from a reputable broker (he on on OSO). I changed out the gauges and that is when I found the alarm had been cut. I finished up changing out the gauges and wired in a System Monitor at the same time. I did not at that time wire back in the audible alarm.

When I started it for the first time since I have owned it, I had an engine alarm on the System Monitor. It was showing the bell and the engine symbol. At that time (and subsequently my first post on this subject), the only indication that may have been outside normal that I could see was the water psi. I did not, nor did I ever get a low water psi alarm. I interpreted this incorrect due to my new-ness with Smartcraft. I was getting appx 2.5 psi at idle at first. I discovered after my initial message that the muffs had slipped a little and more water then should was being blown out the sides. I repositioned them and got about 3.6-4.3 psi at idle.

The only sensors enabled on the System Monitor are the following: Water psi (3.6-4.3 psi), volts (appx 14.4), temp (157 warmed up), hours, tach, oil pressure (51 at idle when warm)fuel used and GPH.

Based on what the scan showed and the correct readings on the Smart Monitor, I do not believe I have a water psi issue here. The ONLY codes the ECM is throwing are the ones already mentioned (tank 1, tank2, pitot, trim and steering). It is clean except for those. There were no other ones except in the freeze frame. I had him clear out what he could and he did that (again). The same 5 from above showed again. Can one of those give me an alarm on the SysMon?

I am not in Guardian mode and all signs are well within the normal range (as per the mechanic). I do not have a print out yet as he saved it improperly on his laptop. He is making another trip out here to rescan and print it out for me.

I did hook back up the audible alarm for a second when all this was going on. When the key is turned, it immediately starts buzzing. No pause for diagnostics or anything. I think it was installed improperly when the 496 was installed in place of the 454 Mag that was there, and so they just cut it. Not sure if the correct sensors are on that motor, or if they are hooked up. There seems to be a sensor bad (permanently closed) or a grounded wire if they are installed.

Hope this helps, and again, I am sorry if I appear all over the place.

Low block Pressure Alarm 2017 4.5 Bravo 3
 

I have been chasing a problem with the help of a mercruser tech. engine has a smartcraft gauge that shows block pressure. Starting out 3 psi block pressure at idle this is ok and constant. At 3ooo rpms starts out at 14 to 20 and as the day goes on 1 or 2 hours of running the pressure starts to fall. Has gone into guarding mode several times saying low block pressure. Only 60 hrs on motor in salt / brackish water. Seem only to do this after a long run . Pressure does get to 5 sometimes at 3000 RPMS. Drives me crazy. Running out of ideas was thinking stuck thermostat as temp never gets above 149 ...HEEEEELP lol And thanks for the help. Kenny

Take a look at your fresh water flush system, if equipped. I have seen where the "Tee" into the sea water system gets gummed up with debris, affecting water pressure, but only at higher RPMs and other variable crap. Many of the factory installed flush systems have a spring-ball-check-valve do-hicky in the "Tee" in the system. Pull that crap out of the Tee. It's not needed. THAT'S what gets gummed up with seaweed and other stuff.

poster says its a 4.5 and in the USA that would be a catalyst engine. The cooling is set up different than Merc models in the past. Who has scanned the engine and has your tech worked on cat engines before ? Possible your issue is the poppet valve. That would be the first place I would check. Next is the water pressure sensor itself . They dislike emi and rfi. make sure no spark plug wires or any electrical connection / wiring is next to the sensor. Next is make sure the sensor is grounded real well.

Have you changed the impeller and how does the housing look internally ??

do you have closed cooling on this app because it was an option ?

Had a conversation with a Merc Tech in Wisconsin , They say it could be a worn impeller that could flex more when hot and there causing less water pressure. Or water movement. ?

I put that on my list as well post # 15. and I would check the housing as mentioned

Ok haunted Boat Engine. Had impeller replaced not to bad of shape. Now Temp never gets above 115 and after a hour or so Low block pressure alarm again. Guessing thermostat stuck open or this poppit valve I have been hearing about.

Ok Round 4 replaced impeller. replaced thermostat, removed water pressure sensor and flushed engine with all ports open. Took the boat out and ran it for over a hour. 2 to 3 psi at idle as high as 19 at WOT 3000 RPMs curse 10 psi. Temp was around 145 to 150 .. Hope this dose it ...

I’ve had three Merc 496 HO’s during the years with an Smartcraft system monitor SC 1000 (see picture) hooked up. In all instances I’ve constantly had the system monitor “showing the bell and the engine symbol” as described by RedHook98. There has never been issues with the engines as far as I have been aware.

I have reasons to believe the phenomena is related to the digital trim sender on the gimbal ring (the transom unit). My senders have been in poor condition and when measuring signal voltage from them it has been way out of range. However, I did once manage to get one sender to produce a voltage within range and at the same time the bell and the engine symbol on system monitor disappeared. I do also have the techmate scan tool and I know for sure that I managed to get rid of the trim sender error code for a short while.

Looking in the attached table of SC 1000 error it does say a fault in the trim circuit will produce a visual warning but no beep.

Of course I’m not 100% sure this is the trouble in my case, but I will replace my digital trim senders and I’m hoping the warning will disappear again. Until then I keep the trim sender completely disconnected as otherwise it interferes with the trim limit control.

Sorry I wasn't able to upload the pictures. For the table just search "smartcraft sc1000 fault table".