Yanmar Tach help needed

[Wotname]

Originally Posted by sharkwatcher

Thanks Bill, "carrying on" is what I've been doing so far. it's not something that has to be fixed, but it just really bothers me when things don't work right. I just have to fix it!

I hear you

As you don't know if it ever worked or when it stopped working correctly, is there anyone you know with a similar engine and who would let you swap the sender or the tach to ascertain if either is faulty.

I think the wiring harness is unlikely for the reasons that others have posted.

[Pizzazz]

I had the same issue with my tach, would read 400-2200, when the actual range was 1000-3400 on the 2GMF. Your pickup and connections are fine. In 90% of the cases the tach needs to be replaced.

I found a Faria 0-4000 rpm adjustable tach that fit nicely into the space (you have to enlarge it just a bit). Reads accurately. Mine is similar to this one below, except it has an hour meter as well:

FARIA Tach 4 Inch Black 4000 RPM Diesel Pulse Pickup Tachometer | eBay

Also check Amazon, they have plenty of similar models with Prime shipping. For example, https://www.amazon.com/KUS-Tachomete...7EW2Z1DGEFT7FF.

It would be ideal if instead of total hours they could make a model that has cumulative rpms as this should be pretty close to actual fuel consumption.

[Vladis]

Hello,
If the belt from the engine to the alternator slips, the displayed revs/m are lower.
Regards, Vladis

[19thol]

Hey, where is that tack sensor on the 2gm, I've been looking, my manual doesn't say. But from reading it sounds like it's on the bell housing?

[Wotname]

Originally Posted by 19thol

Hey, where is that tack sensor on the 2gm, I've been looking, my manual doesn't say. But from reading it sounds like it's on the bell housing?

It is on the bell housing, near the top on the LHS (looking from the gearbox end).

[Wotname]

Originally Posted by Vladis

Hello,
If the belt from the engine to the alternator slips, the displayed revs/m are lower.
Regards, Vladis

While true for tachs which are sensed from the alternator, the stock Yanmar GM series of engines have a flywheel sensor for the tach.

[windsweptms]

Try cleaning and or tightening the spade connectors on the fly wheel pickup, I have fixed many GM series tachometer this way, usually cycling the spade connections will correct the issue. Regards, Windswept marine services of Baltimore

[sharkwatcher]

Thanks for all the help and suggestions guys!

[sharkwatcher]

Problem solved! I installed today an alternator triggered tach https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1. It was an easy install, simple to calibrate with the help of a laser tach, and best of all, worked perfectly. Rather than pulling a new wire to run from the alternator to the "sender" post on the tach, I simply added an extension to the orange sensor wire going to the magnetic sensor after unplugging the sensor. I double checked it thru the entire range, verifying the engine rpms with the laser tach, PERFECT and once again, PROBLEM SOLVED! Thanks again everyone for your help and suggestions.

[troubadour_m33]

Sharkwatcher, I have two questions - hoping you can help.

1) It looks like the Sierra 82302 tach is 3" in diameter. Was that a simple drop-in replacement in your Yanmar instrument panel? As far as I know, most 2GM and 3GM engines had 3 3/8" tachs.

2) Did you need to buy a pickup for your alternator and, if so, what did you get?

Thanks