Lets solve this!!

[Solo79]

Il skip right to the chase. Have 2006 Monterey 248 montura whit a Volvo penta 5.7 gi-e. Been having some troubles. The enginen throws audio motoralarm. This happens when the boat has been running for 20-30 min. I have timed it and it's always in this timespan speed or drivestyle doesn't matter. Just Before I get the alarm I can fel the motor running a little bit rough on low rpm about 2000. The alarm reduce power over 2500 rpm. It sounds a little bit if the engine is not working at all cylinders. I have done some shotgun repair whiteout success. I have replaced, termostat, IAC valve, checked 3 spark plugs that seems OK, measured that both temp sensors and exhaust sensor are not causing the alarm. Changed impreller. All gauges on dach are OK Whit solid readings. I'm now gonna proceed to check ignition, fuelpump. Summary: no problem starting boat. Hard alarm after 20-30 min every time. Just before hard alarm, engine rough on low rpm. Had this problem since I got to boat in water in juni, someone have any ideas?
Br Marcus

 

[Bondo]

Ayuh,.... Welcome Aboard,.... Check the Contents of the fuel filter, for anything but clean fresh gasoline, 'n then change the filter,....

 

[Thalasso]

Ayuh,.... Welcome Aboard,.... Check the Contents of the fuel filter, for anything but clean fresh gasoline, 'n then change the filter,....

That wouldn't throw codes.

 

[Grub54891]

That wouldn't throw codes.

it should if it has a water sensor for the fuel. Not sure if it has one, as the alarm would be on from the start.

 

[Dave-R]

Could be an O2 sensor, If one is bad the long term fuel learning will restrict rpms at about 2500. This will need to reset with a diagnostic tool. When first bringing my engine back from the dead, I had this alarm in. I cleared it and it never came back in, A bad MAP sensor can also give you a problem,like what you describe., Good luck Dave-R

 

[ericga]

clogged fuel pressure reglator screen is a common problem on these engines. Have you check yours? Finding a marine code scanner would save you time.

 

[Solo79]

Could be an O2 sensor, If one is bad the long term fuel learning will restrict rpms at about 2500. This will need to reset with a diagnostic tool. When first bringing my engine back from the dead, I had this alarm in. I cleared it and it never came back in, A bad MAP sensor can also give you a problem,like what you describe., Good luck Dave-R

No sensor for water in fuel on this engine, have tough about the map but have not found info how to measure it. Do you now?

 

[Solo79]

clogged fuel pressure reglator screen is a common problem on these engines. Have you check yours? Finding a marine code scanner would save you time.

Checked the screen and I replaced the regulator last year, don't think that's the problem, of the stuff I read etc, haven't found a fuel problem that sets of hard engine alarm

 

[Solo79]

Could be an O2 sensor, If one is bad the long term fuel learning will restrict rpms at about 2500. This will need to reset with a diagnostic tool. When first bringing my engine back from the dead, I had this alarm in. I cleared it and it never came back in, A bad MAP sensor can also give you a problem,like what you describe., Good luck Dave-R

What do you mean buy "Could be an O2 sensor, If one is bad the long term fuel learning will restrict rpms at about 2500" don't understand "long term fuel learning"

 

[Scott Danforth]

Could be an O2 sensor

O2 sensor? On a 2006 VP marine motor? Unlikely since O2 sensors did not get used until the LS motors were being developed in 2009

 

[Shaper79]

That's the thing , on these computer controled engines. You gotta have a scan tool. Rinda technology inc. has em. I think the scan tool was about 500$

 

[Solo79]

Yes, it's more complicated whiteout a scantool but for me it's not Worth it, a scsntool is going to cost me about 1000 $ Whit delivery to Europe. Does anybody now how to measure the MAP sensor?

 

[Solo79]

Bump about measure MAP

 

[Solo79]

Some updates: clean all connections to battery etc, checked all the sparkplugs witch looked find and disconnected the oil pressure switch and went for a trip. NO alarm, NO limpmode but after about 20 min in the engine was making the same problems as before, thus I didn't have the alarm restricting me I could run the boat for some time and the engine clearly misfires around 2000 rpm but runs good otherwise, the misfires commes in rapid clusters Whit about 2-3 sec intervals. I suspect bad rotor or even more one or several of the cables that run from the rotor to the sparkplugs (don't now the name in English) haven't connected the oil switch to check if the alarm goes of again but vill do tomorrow. But oil pressure switch creating a alarm from misfire in one of the cylinders???

 

[bruceb58]

A faulty oil pressure switch puts your engine in SLOW mode. It is in series with a water temp switch as well. In SLOW mode, the ECU starts modulating your injectors to keep RPM below 2500. Sounds like you had that problem but possibly an additional one.

 

[kenny nunez]

You may be getting a water pressure signal, I just had a similar problem on my Donzi. Have you checked the water intake from the thermostat housing back through the out drive. Some one on this site showed pictures of something lodged in the water passage in the bellhousing. It might a good idea to remove the outdrive just to make sure the passages are clear.

 

[bruceb58]

There is no water pressure sensor.

 

[Solo79]

A faulty oil pressure switch puts your engine in SLOW mode. It is in series with a water temp switch as well. In SLOW mode, the ECU starts modulating your injectors to keep RPM below 2500. Sounds like you had that problem but possibly an additional one.

Yes, it seems to be two separate problems misfire in one or multiple cylinders and faulty oil switch but I can't let go that limp alarm always goes of when the engine misfires on low rpm except when I unplug the switch. Can't think of any reason that worse combustion in a cylinder should trip the oil switch but I will measure ohm on all the cables to the sparkplugs an do some more tests but I feels like its solvable thanks for all the reply's!

 

[bruceb58]

I said series before but it may actually be in parallel with the water temp switch. Take a look at that one as well.

 

[mklearl]

I don't think it's the map sensor but here you go.
http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/how-to-test-the-map-sensor-1