Perplexing beeping from Mercury 60hp controls

[nicksharpe]

I have a recurring problem which does not seem serious but is perplexing me and I feel could cause more problems in the future.

Set up is a 2002 60hp 4-stroke Mariner, with a Mercury controls.

If I let the engine sit on tick over for a few minutes and then move back into gear and accelerate a loud alarm sound comes from behind the steering wheel / the throttle housing. Power from the engine begins to pulse in quite a dramatic way.

I can then bring the engine back to neutral whereby the beeping stops, put it back in gear and accelerate and the problem goes away.

If I increase the revs without the engine in gear there is no pulsing of power, it's as smooth as ever.

I'm tempted to think it's some kind of electrical fault. I did consider that it might be overheating as the tell-tale slows to a trickle when the engine is in neutral. Does anyone have any ideas at all?

Thanks in advance for your help,

Nick

PS - Pics here if they'd be useful: https://www.dropbox.com/sh/lvkuzbjfj...NJueWHzua?dl=0

[Nos4r2]

It's probably getting too hot. At a guess the pulsing is limp mode.

Get it plugged in at a tech,check impeller/water pressure/exhaust gaskets etc

[nicksharpe]

Thanks vampire guy. The tell tale is cool though - when the thermostat has been playing up in the past it's been boiling hot.

[A1an]

Can you disconnect temp sensor when problem occurs?

I had a similar issue on a 1998 Mariner which will be the same as yours, it turned out to be an oil level/temp module on its way out. Iirc it was an orange wire.

https://www.ebay.co.uk/itm/OIL-CONTR...-/233266160692

[pagick]

I had a 40. efi merc for one season. When the thermostat went out it went into limp and the beeping started. Im guessing any triggered sensor sets off the alarm.

[matt h]

Water pump impeller , spinning around its collar, worth checking!

[Turbodiesel]

Sounds like temperature issues.