8.1 Horizon problem

[Michael Mirra]

Hoping some one can point me in the right direction to solve this problem. After cursing for about an hour over 3000 rpms my port engine will set off an alarm and the rpm will drop to around 1100. This has happened a few time but if i get back just using the starboard engine and start it up the next day it will be fine. Run it on plane for about an hour and the same thing happens again. The last time it happened if i turned off the engine and then restarted it, it would go for about five minutes and throw the alarm and slow down. I guess its putting me in guardian mode. After turning it on and off a few times and getting it to run for five minutes it finally would not reset at all and would just run at about 1100 rpm with the alarm sounding. I have ruled out fuel filters and don't think its the gas because the other engine is fine. I guess it could be crap in the tank but the tank is usually close to full. After searching the forums i am leaning towards a faulty raw water pressure sensor or possible a faulty plug. Has any one had this problem or have any ideas?

 

[paulswagelock]

Fuel issues won't put you in Guardian mode. Same with a bad plug. My first thought is the ECM believes you are over-temperature and limiting the RPM.
That could be a faulty sensor or faulty raw water pump/inlet.

 

[Jimmy Buoy]

How's your water flow out the exhaust? It could be a overheat in your exhaust manifolds due to blockages. If the water flow seems slower on the problem engine, check the temps of the exhaust manifolds and risers from a cold start-up to nominal running temps. I believe the guardian mode is mostly triggered by possible overheat issues.

 

[Michael Mirra]

The water flow seems to be the same from both engines. Both water pumps and impellers were replace over the winter. Thought maybe there could be an obstruction in port one. Temp gauge says 160* that what is leading me to believe it may be a faulty . I plan on checking the sea strainer when i get back this week end, but if it were clogged i would expect to see a more limited exhaust flow.

 

[liv2ryde100]

theres temp sensors in in the risers, i had one go bad did the same thing. however, smart thing to do in this situation is put a scanner on it and see what the code is.

 

[Mittens]

what kind of alarm do you have going on? solid or beeping...?

Constant tone alarms are for:
1.) engine coolant temp overheat,
2.) low engine oil pressure,
3.) engine overspeed,
4.) exhaust manifold cooling temp overheat
5.) sea pump PSI low (FYI This is kind of common, And is said to not show up in the history. The only way to know is to watch this sensor live as it happens. Make sure all you grounds are tight on and around the engine. And if this sensor has any paint on it it could be losing it's ground and sounding the alarm. Or you could have picked up some air bubbles for a short time till you slowed down, Or the impeller, or impeller housing is starting to fail. This is Just a thought of what could be happening is all. Good luck with it.)

Constant beep alarms are for:
1.) low outdrive lube level.

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


you can check some of the sensors google how to Om them out and things.

 

[Michael Mirra]

Thanks for the input. I am going to try and find all the sensors and start with that. I ordered a Rinda Testpro and am hoping that brings up the code. What makes me think it is a sensor is the first time this happened i was coming back from a 4.5 hour trip. The boat ran at 3400 rpm's the whole time and ran great. I stopped for fuel and lunch and the boat sat for close to an hour cooling down. When i started it up to leave it gave the constant beep nd went into guardian mode. I hobbled back to my slip (10 miles) on one engine and shut it down. The next time i used it there was no problem but i ran it for less than an hour. Always seems to do it after an hour run but doesn't seem to be over heated.

 

[SeadawgVB]

Michael, sorry to hear the issues with your new boat. Please keep the thread updated and let us know the final solution. Good luck!

 

[Phasma]

I ran into the same problem a little while back. It turned out that my negative leads were loose on the batteries for my starboard engine. The ECM was running straight off the alternator and didn't like the rough DC current being supplied nor the higher voltage. Cleaned up the battery connectors, tightened and tested. No problem since. I can be such a duh some times.

 

[rondds]

I had a bad manifold temp sensor causing an alarm. Replaced and all's well. Used the Diacom software connected to a laptop.

 

[Michael Mirra]

I had a bad manifold temp sensor causing an alarm. Replaced and all's well. Used the Diacom software connected to a laptop.

What code did it give you? I was thinking it must be a sensor, where is the one you replaced located?

 

[rondds]

It was something like Manifold air temp. The sensor is on the top of the exhaust manifold. You'll find it by looking for a wire leading to it.

 

[Tdady]

I had a similar issue and it turned out to be a bad spark plug wire. It was a bitch to diagnose though, took me almost 2 seasons!!

 

[Biagio Fasolo]

How's your water flow out the exhaust? It could be a overheat in your exhaust manifolds due to blockages. If the water flow seems slower on the problem engine, check the temps of the exhaust manifolds and risers from a cold start-up to nominal running temps. I believe the guardian mode is mostly triggered by possible overheat issues.

Hi I changed my sea water pump over winter and I went to start it today and no water flow so I took the valve off and started boat blew a bunch of shit out and then shut it off and put valve back on then started it and had flow but not as much as port side and strb engine alarm diagnostic is still on I had the back of boat tied down and put both motors in gear idling for 10 minutes no over heat issue not sure if I should take it out see how it goes any pointers?

 

[Jimmy Buoy]

Hi I changed my sea water pump over winter and I went to start it today and no water flow so I took the valve off and started boat blew a bunch of shit out and then shut it off and put valve back on then started it and had flow but not as much as port side and strb engine alarm diagnostic is still on I had the back of boat tied down and put both motors in gear idling for 10 minutes no over heat issue not sure if I should take it out see how it goes any pointers?

I'm not familiar with your 454 cooling system, just the 8.1 system. The 8.1 seems to be quite different from other power plants so maybe another member with a 454 will step in to help.