2002 mercury efi constant alarm going off??

[pursuit1322]

i have a 2002 mercury outboard on my 21 foot pursuit yesterday when i was out a constant alarm would go off mainly when i would push it hard to go on plane seems as tho i have good water flow,oil pressure gauge seems to read differnt from time to time but the guage is on the older side.i was out for probably 4 hrs and the alarm went off 4 times mostly when im going to plane it out and once idleing underway nothing also the motor would run ruff when the alarm went off i would instantly shut it off let it sit then go and it would be ok.does anyone no what this can be the motor has 50-100 hours on her.thanks...Dan

 

[Texasmark]

Re: 2002 mercury efi constant alarm going off??

Sounds like a sticking stat. Had similar but worse problem before; mine stuck closed. As you are planing out you are putting a lot of heat into the engine. Once you plane out, water pressure opens the popoff valve which bypasses the stat. As time goes by and it gets worse, you will be running at low speed or idling (where the popoff is closed) and the horn will sound.

Get a new pair of stats, one of them is going bad......I assume it's a v engine beins you said you had a 21' boat.

Mark