Mercruiser 5.0 engine alarm

[USS MINNOW]

2011 Tahoe Q7SSi, 5.0 MPI Mercruiser with less than 5 hrs. Took it out yesterday and it ran great, however after about 3 hrs, an alarm sounded. Single beep every 2 or 3 minutes, (or so). Still running OK, oil pressure looked fine, temp fine, couldn't find an obvious explanation.

The only thing I noticed was prior to the 1st sounding as I was coming out of the throttle, it seemed as though it was running rough, (back at idle). It then shut off. I looked everything over as best I could then started it back up. It started immediately and seemed to be idling perfect again. No other issues for the next several minutes except for the alarm every couple of minutes so we took it out and came home.

Any thoughts other than take it back to the dealer who won't be open until tomorrow?

 

[dubs283]

Re: Mercruiser 5.0 engine alarm

gear lube monitor low??

otherwise if all the visual inspections check out you will need to check fault codes with a cds (computer)

 

[USS MINNOW]

Re: Mercruiser 5.0 engine alarm

Gear lube is OK.

Edit...when the key is initially turned on there is the 2 second beep. After this occurred, this initial beep became 4 to 5 seconds.

 

[dubs283]

Re: Mercruiser 5.0 engine alarm

when the key is initially turned on there is the 2 second beep.

that is normal - the initial beep is to let you know the audible portion of the warning system works

the succeeding beeps are indicating a fault somewhere in the system - since you visially verify the oil, temp and lube the only other culprits are sensor faults, seeing as its not a "hard" fault (constant horn), its most likely a non-critical issue

80% of the time on mpi engines the fault is an IAC motor - easy swap

 

[USS MINNOW]

Re: Mercruiser 5.0 engine alarm

I felt it was non-critical as it was running too good but took it out to be safe and the alarm was very irritating.

Thanks for the replies.

 

[USS MINNOW]

Re: Mercruiser 5.0 engine alarm

I took the boat to the dealer today. They hooked the computer up and it showed misfires on #1 and #7. He found 2 loose plug wires on the distributor cap, you guessed it, #1 and #7. He fixed those, replaced the plugs on 1 and 7 and ran it a few minutes.....no codes. He then took it to the lake, ran a complete diagnostic test, ran it on the lake approx 20 to 30 minutes, no codes, ran great. (Got it up to 62 mph)

He also found a problem with the throttle cable, (a little slack), and adjusted that and now it idles perfectly.

I hope the problems are now solved but can't find out until Sunday at best. :joyous: