Merc 6.2MPI won't start after engine alarm

[Lyman713]

I have a 2002 Merc 6.2MPI on a Sea Ray boat. Was out yesterday and the engine alarm (2 beeps) would sound every 3-5 minutes. Shut down and checked fluid levels - they were ok, but my oil pressure sensor would fluctuate a great deal. It woudl start up and run - all sounded ok - but then the alarm would happen and the oil pressure guage would vary from 0 to 40 (normal, middle position).

Shut down again and it started right up again, but... same story.

Finally, shut down for lunch and fishing, hoping to limp back to the dock after, but, after 2-3 hours stopped the engine would crank, but wouldn't start at all.

Any thoughts or insight would be appreciated. The engine only has about 300 hours on it and the oil and filter was just changed.

Thanks in advance!!

 

[Lyman713]

Re: Merc 6.2MPI won't start after engine alarm

Update -- Tried to start today -- the engine would sputter for 2-3 seconds when cranking to start, but wouldn't turn over.

The gas is non-ethanol, but has been in there for several months now... but, it did run for 20 minutes or so and started up ok each time I re-started (except the last time!).

I don't think fuel would cause the engine alarm and I don't think the flucuating oil pressure guage woudl be from bad gas, but wanted to bring this up.

Any suggestions on where to start would be great!

 

[dingdongs]

Re: Merc 6.2MPI won't start after engine alarm

switch could be bad but don't know if you can link out the terminals on wire side to fool the electronics but may be faulty giving you erratic oil pressures and also preventing starting,this can be donne on carbed 5 litre to get fuel pump working as needs this once cranking circuit done as no oil pressure b4 its running to get fuel pumps circuit good.Therefore more than likely the oil sender playing up.

 

[harleyman1975]

Re: Merc 6.2MPI won't start after engine alarm

I will assume you have physically checked the oil and it is up to the full mark so then try a new oil pressure switch...or you could test for voltage at fuel pump (but this would not explain the fluxuating oil pressure) so I guess you need to change oil pressure switch to eliminate that.

 

[Fun Times]

Re: Merc 6.2MPI won't start after engine alarm

What is the condition and size (CCA ?) of the battery and battery cable ends in? Seems like you may have an intermittent electrical connection problem somewhere.

Check the cables at all ends for any type of corrosion build up.

Also try inspecting the black 10 pin wiring harness cannon plug located on the engine. Then try wiggling the plug around with the key on to see if your gauges and 12 volt power fluctuate.

Let us know what you find, good luck.