[Captain Aubrey]

Hi All,
When I turn on the battery the alarm sounds.
Start the engine... alarm stops, as it should.
Stop the engine ... alarm sounds and stays sounding.

This one is new to me, all was well until I changed the battery.
Also, the engine is showing a new tendency to stall when idling, when cold, and is slower to start, needing some throttle to get going.

Where should I start looking?

 

[dabnis]

Hi All,
When I turn on the battery the alarm sounds.
Start the engine... alarm stops, as it should.
Stop the engine ... alarm sounds and stays sounding.

This one is new to me, all was well until I changed the battery.
Also, the engine is showing a new tendency to stall when idling, when cold, and is slower to start, needing some throttle to get going.

Where should I start looking?

My, that is a puzzle. The VW diesels I had had a battery powered solenoid that acted as a fuel on/off valve, no hands on experience with Yanmars.

I can't think of why a new battery would effect fuel delivery unless you have an electric fuel lift pump? Perhaps you hit or dislodged a fuel line connection when installing the battery, allowing a minor air leak?

"Slower to start"? If your engine has glow plugs, maybe they are not getting enough current, maybe go over all electric connections to make sure they are clean & tight.

Once it is warm does it run properly? If so, it may be back to the glow plugs.

Interesting, let us know what you find.

Paul T

 

[PaulinVictoria]

The alarm is oil pressure, should sound when you have power without the engine running although it may take a few seconds to sound after stopping. Maybe the new battery finally has enough juice to sound the buzzer?
As to the problem starting etc, sounds like the timing is off. Mine used to take several seconds, needed throttle on/off and so on, generally a bit of a pain to start. Adjusted the timing and it now starts in a second or two with no throttle at all.

 

[dabnis]

The alarm is oil pressure, should sound when you have power without the engine running although it may take a few seconds to sound after stopping. Maybe the new battery finally has enough juice to sound the buzzer?
As to the problem starting etc, sounds like the timing is off. Mine used to take several seconds, needed throttle on/off and so on, generally a bit of a pain to start. Adjusted the timing and it now starts in a second or two with no throttle at all.

It kind of sounds like the starting, rough when cold problem, started when he changed the battery? I am wondering if any other work was done at or near the time the problem started. I am assuming it started & ran OK before hand?

Paul T

 

[smurphny]

If you reversed polarity when installing the new battery, even momentarily, it may have fried the diodes in your alternator. I had this happen. The symptoms sound similar. Somehow after the alternator is shorted, a backfeed develops into the alarm circuit.

 

[aa3jy]

Hi All,
When I turn on the battery the alarm sounds.
Start the engine... alarm stops, as it should.
Stop the engine ... alarm sounds and stays sounding.

Where should I start looking?

Normal...look in you Yanmar shop manual,if you have one, explains the alarms

 

[smurphny]

Just turning on the battery should not activate the alarm circuit. I think that's the key piece of evidence. If the alarm is sounding before the key is turned to the ON position, there may well be feedback through the alternator to the neutral into the alarm buzzer. The problem is not at the sending unit.

 

[aa3jy]

I suspect your key switch is shorted if the key is in the off position and alarm sounds.Test switch for continuity.