Jump to content

Lack of revs....


Saintly Fish
 Share

Recommended Posts

Or at least a lack of revs being displayed in the counter. 
Apart from a loose connection  on the back of the dash unit, what else could cause this? And anybody got a clue where the needle gets the engine signal from?? 
Yanmar 6lpa dte

Link to comment
Share on other sites

5 minutes ago, Andy135 said:

Is the alternator still working/charging? Do you have a voltmeter on the dash and does it read 13-14v? If not, it may be that your alternator is failing.

If you remember, when I had my new battery charger installed the alternator was removed and tested (couple of months ago). All was fine with it. 

Link to comment
Share on other sites

12 minutes ago, Saintly Fish said:

If you remember, when I had my new battery charger installed the alternator was removed and tested (couple of months ago). All was fine with it. 

I'd have thought it would be a loose connection somewhere then, either at the tacho end or at the alternator end. Any chance you could have knocked a connection loose when removing/reinstalling your water pump recently?

Link to comment
Share on other sites

14 minutes ago, Andy135 said:

I'd have thought it would be a loose connection somewhere then, either at the tacho end or at the alternator end. Any chance you could have knocked a connection loose when removing/reinstalling your water pump recently?

Possible I suppose, it's on the other side though. But I did also change the anodes and two are on the same side as the alternator. I will have a look later! I'm obvs not as slim as I thought. 

Link to comment
Share on other sites

5 hours ago, Saintly Fish said:

Or at least a lack of revs being displayed in the counter. 
Apart from a loose connection  on the back of the dash unit, what else could cause this? And anybody got a clue where the needle gets the engine signal from?? 
Yanmar 6lpa dte

Normally, with an older tractor engines , the rev counter gets the signal from the 'W' terminal of the alternator.

With newer engines, they get the signal from the crankshaft sensor, or some times the camshaft sensor and use the ecu to double the reading (camshaft turns at half engine speed).

  • Thanks 1
Link to comment
Share on other sites

4 hours ago, Saintly Fish said:

Apparently the tachometer sensor is here...

5F082232-CD56-4B29-B3B5-844B9D35B5BF.jpeg.c60369ac890e37a6e13ec10c71b98586.jpeg

On the flywheel housing. Port side of the engine. 
I will go and check all connections however. 

If all the connections are sound, and if it's a hall effect sensor check the gap between the sensor and the flywheel teeth. The sensor bracket may have been nudged/bent out away from the teeth, which would give no signal. The gap between the two is usually surprisingly small when working properly.

Link to comment
Share on other sites

5 minutes ago, Saintly Fish said:

No idea what that is, I've not got the same googling time as you.

No googling required. These are often used on cars to drive tachos, abs systems etc. I had to fight with one on a kit car I built years ago - never did get it to work properly in the end.

https://en.wikipedia.org/wiki/Hall_effect_sensor

  • Thanks 1
Link to comment
Share on other sites

6 hours ago, Saintly Fish said:

Apparently the tachometer sensor is here...

5F082232-CD56-4B29-B3B5-844B9D35B5BF.jpeg.c60369ac890e37a6e13ec10c71b98586.jpeg

On the flywheel housing. Port side of the engine. 
I will go and check all connections however. 

Those hall effect (magnetic) sensors rarely fail. First port of call will be to check the wiring, especially the dashboard end. As a point of interest, the rev counter gauge itself could be at fault, I have known plenty to fail. 

  • Informative 1
Link to comment
Share on other sites

Work back from the dash to the engine. If you can get a new Rev counter or a way to check the signal is there.

It sounds like a bad connection so check it at the helm end and look for trapped wires in the middle. 
 

Hall effect sensors are very robust, far more so than optical ones so I would expect a broken wire somewhere 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...