Mercruiser 3.0 ignition timing jumping

[anddah]

I?ve got a strange problem with my Mercruiser 3.0 -07. When I check the timing it won?t stay stable. First I figured that I was because it was because of the advanced moving because of a little bit unstable idle.

When I checked the maximum advance it should be 25 BTD if I don?t remember it all wrong. But when I set the timing light to 25 degrees it jumps between 12 degrees before and 0 (37 and 25) BTD.

Anyone got any suggestions on what that could be wrong?

 

[Bondo]

Re: Mercruiser 3.0 ignition timing jumping

I’ve got a strange problem with my Mercruiser 3.0 -07. When I check the timing it won’t stay stable. First I figured that I was because it was because of the advanced moving because of a little bit unstable idle.

When I checked the maximum advance it should be 25 BTD if I don’t remember it all wrong. But when I set the timing light to 25 degrees it jumps between 12 degrees before and 0 (37 and 25) BTD.

Anyone got any suggestions on what that could be wrong?

Ayuh,... Welcome Aboard,... Which ignition has it got,..??

Did ya put it in base mode, if it's supposed to be,..??

 

[kd7isf]

Re: Mercruiser 3.0 ignition timing jumping

Check timing in "base timing mode"
The ECM varies the timing based on sensor inputs.
Base timing mode prevents the computer doing that while you shoot the timing..

Hope this helps

 

[Don S]

Re: Mercruiser 3.0 ignition timing jumping

You have an EST ignition system, and the timing does bounce around a lot, but it's not a problem. Really, it's quite normal. That is also the reason for putting the ignition into base timing mode when setting the timing. The base timing mode locks it down so it doesn't move around in order for you to set it. Once you get over around 1500 rpm or more you should see it settle down.
The module in the distributor is just reacting to very small changes in rpm that you can't see or hear.

 

[anddah]

Re: Mercruiser 3.0 ignition timing jumping

You have an EST ignition system, and the timing does bounce around a lot, but it's not a problem. Really, it's quite normal. That is also the reason for putting the ignition into base timing mode when setting the timing. The base timing mode locks it down so it doesn't move around in order for you to set it. Once you get over around 1500 rpm or more you should see it settle down.
The module in the distributor is just reacting to very small changes in rpm that you can't see or hear.

It's a EST ignition system and I've timed it in base timing mode. It's when I check the timing over 2000 RPM (for total advance) that it jumps between 25 BTD and 32 BTD (I don't rember if it's 25 BTD or 27 BTD but it's jumps between total advance and -12 degrees).

I guess that it's some sort of electric problem but I dont know where to start. I would like to remove all boat electrics and start up the engine on it's own to see if i have any bad grounds or bad equipment but I don't know how.