chromicant
03.06.2021 6:41:15
1992 Rinker 4.3 Merc. LX Alpha I, Gen. II. Two batteries with a Perko switch. [links]
See full version: Tach jumping around
1992 Rinker 4.3 Merc. LX Alpha I, Gen. II. Two batteries with a Perko switch. [links]
Took the boat out of storage and after rebuilding the Carb, I was adjusting the air micture screws. Upon paying close attention to the tach, I noticed it was jumping around. I tapped on it and it moved around.
Yes, I did search the threads and found a couple emails but nothing adequate to answer my questions so I decided to post the questions.
I have to admit, I have no idea how tachs work, except to say, don't they normally hook up to the #1 cylinder? I checked the wires on the back of the guage and none of the wires were loose.
1992 Rinker 4.3 Merc. LX Alpha I, Gen. II. Two batteries with a Perko switch.
Yes, I did search the threads and found a couple emails but nothing adequate to answer my questions so I decided to post the questions. [links]
Took the boat out of storage and after rebuilding the Carb, I was adjusting the air micture screws. Upon paying close attention to the tach, I noticed it was jumping around. I tapped on it and it moved around.
A less common problem is a poor connection in the RPM signal wire. In this case, the needle will usually bounce around below the actual RPM reading because it will miss some of the voltage spikes. Look for corrosion, a broken wire, or a loose connection anywhere between the coil terminal and the tachometer.
First, let's narrow down the symptoms. Too many times we get emails that just say the tach is "acting weird" or is "inaccurate". Acting weird how? Is the inaccuracty consistent or random? Different symptoms can have different causes, so specifics and details can help.
AiM loggers can use the special AiM ARP03 RPM signal filter to convert the signal into a clean, square wave signal. here
This is the fun one. There are a few possibilities here, but they're all easy to fix. In fact, the fixes are often easier than actually finding the real problem, so you might want to just go ahead and try all of the possible cures instead of doggedly chasing down the root cause. more
Inconsistent readings or jumping needle:
The tach needle bounces up and down instead of holding steady. If you hold the engine at a constant speed, the needle continues to move around. Shift lights fire at odd times, usually long before redline.
Consistent Inaccuracy: An Easy Fix
After I tightened my loose throttle cable, the jumpiness went away.
I know that on some of other Toyotas, the tach gets its signal from the ignitor and a jumpy tach on other Toyota can indicate a failing ignitor, but since I'm new to the Land Cruiser, I'm kind of confused on the LC ignitition system. All I see is a tiny contraption that powers the main coil wire to the distributor. Is that the ignitor/coil? Seems awful small. [links]
Just curious though, is there any after market instrument panel out there that can be used or installed easily? I would be replacing it with a OEM one if I really have to. As long as this is not triggered by any kind of voltage discrepancy (alternator), I'm OK with it. [links]
The alternator tachometer takes a pulse from the DC charging alternator AC winding. This signal is a frequency directly proportional to the engine speed.
How do you troubleshoot a boat tachometer? [links]
Most tach jumping is caused by loose or corroded connectors at either point. There is a chance the tach is bad from moisture, but you can check the connectors quickly and do a clean and lube on them. Tachs are more sensitive to moisture than other gauges. [links]