RPM guage question

[slayer2]

Does anyone have any idea what would cause an rpm guage to not work on a Crestliner 1760 Fishhawk . I have checked all wiring and fuses and everything looks good and it still don't work. Is there something on the motor that needs attention? I looked at all the wiring and it all looks good and fuses ok.

 

[BonairII]

Re: RPM guage question

Your rectifier is prob blown. Hookup a multimeter to your battery(while motor is running)...if you're battery isn't showing 14volts(or somewhere in the neighborhood), that means your battery isn't charging and it's prob a bad rectifier.

 

[metriccrescentwrench]

Re: RPM guage question

First, what engine's on your boat?

Right behind the #1 most common reason that tachs don't work (bad rectifier) is the #2 reason - no power to the tach, and #3 - bad tach.

 

[slayer2]

Re: RPM guage question

first, what engine's on your boat?

Right behind the #1 most common reason that tachs don't work (bad rectifier) is the #2 reason - no power to the tach, and #3 - bad tach.

merc 2004, 125, 2 strk

where is this rectifier located? I will check it out on the motor breakdown and see

 

[Silvertip]

Re: RPM guage question

You very likely have a voltmeter on the console of your boat. Turn the key on and note the reading. Start the engine and note the reading. If the voltmeter reads about 14 volts at 1500 - 2000 rpm the rectifier is probably not the problem. The tach requires +12 volts at the "I" terminal, ground at the ground terminal and a pulse on the send line "S" terminal. Missing any of those means the tach won't work. If you don't have a multi-tester or know how to use one, you will need professional help. Fuses are not the problem with gauges unless the one under the engine cowl pops. But then the engine doesn't crank and the tilt & trim doesn't work either. Gauges are powered from the engine harness, not the boat harness which is the one with all the fuses.

 

[slayer2]

Re: RPM guage question

well... I found this little issue... u think maybe this could be a problem as to why the tach is not working?! +

 

[Silvertip]

Re: RPM guage question

You didn't answer the question in my last post. How about some words to go along with what are we looking at?

 

[slayer2]

Re: RPM guage question

You didn't answer the question in my last post. How about some words to go along with what are we looking at?

This is the voltage regulator on the mercury. I was going to grab my volt meter; but after seeing this I did not go any further. The regulator has like burst / bulge on the case and a little hole in the side of it with dark black crud that leaked out down the side of the spark plug cases. I assume this to be the trouble until I get another one Thoughts?

 

[Silvertip]

Re: RPM guage question

Does the hole look like something beneath the surface might have "burned" or become very hot and melted the potting (black rubbery) material? And how about the question of the voltmeter. That si still a critical issue. Spending money on somethng that is relatively expensive is a waste of money and time since many times that's not the problem. Troubleshoot, isolate, and then repair or replace once you've proven whats wrong. So again, answer the questions! Does you boat have a voltmeter on the dash. If so, what does it read at idle and 2000 rpm. If it doesn't have a voltmeter, attach your voltmeter directly to the battery and repeat the test. And then check to make sure you have +12 volts on the "I" terminal of the gauge with the key in the run position. Ensure you have a good ground on the gauge. These are "free" checks. Replacing the voltage regulator is NOT free.

 

[slayer2]

Re: RPM guage question

I will hook the muffs up and check the voltage. If the voltmeter on the dash works as I believe it does, it is close to 13 volts running...at what rpm's.... I will advise

As far as the hole in the regulator goes, it does look like it got warm. The back side of it is aluminum so an heat if any had to be generated electrically from inside like maybe a short or something. I still intend on purchasing one because it obviously is a failure as it was not designed to be like this obviously. I will check the voltage and let u know soon. How to I find this "I" terminal on the tach...it has 3 wires in a moles plug config and not labeled, just color coded wires.

 

[Silvertip]

Re: RPM guage question

If the other gaugews are working properly then the tach probably has power as well. Purpp\le is typically the +12 volt line. Gray is the send signal and ground is typically black but may be white as well. Pull the plug and probe the terminals. For all you know all that needs to be done is re-seat the plug a time or two to burnish the contacts.

 

[slayer2]

Re: RPM guage question

The plug has been removed several times (4) ...I thought of that too

Here are the results

Key on only- gauge reads just under 13, battery was 13.05. ( I have had it charging today on a charger)
Engine running at idle- gauge the same and meter on battery was the same also 13.05 v
Engine rev to around 2000- guage the same and meter reading 13.05 again on the battery

Solid 12v present at tech on purple to ground

Tach lights do work well as well, did not tell u that