Teleflex 7k tachometer

[jwellcraft]

Just got this for christmas and installation went fine. Motor idled at 1,080 rmps on the hose so I took it out to check everything in the water. When the tachometer reached 4,500-4,700 the needle dropped back down to zero and as soon as I redeuced the throttle it caught back up so I gave it more throtlle and as soon as it reached the same spot it dropped to zero again. What could be the problem? The motor never lost any power when this happened.

 

[ezeke]

Re: Teleflex 7k tachometer

See item 7: http://www.downloadingfiles.co.uk/teleflexfiles/gauges/Tachometers Outboards.pdf

 

[jwellcraft]

Re: Teleflex 7k tachometer

Thanks for the helpful info, will consult with my electrician on getting this and see how it goes.

 

[jwellcraft]

Re: Teleflex 7k tachometer

Hi,

I added a 2600 ohm resistor to this and it still does the same thing but now as it reaches 4,000 rmps it drops back to zero so I guess its a faulty tach.

 

[ezeke]

Re: Teleflex 7k tachometer

Do you have it set on 6p?

 

[psteurer]

Re: Teleflex 7k tachometer

I do not see what engine you are running in regard to horsepower and model year. All of these 2 cycle engines since 1971 would be set to either 5P or 6P depending upon the year and hp. Your problem could be as simple as being set to the wrong number of poles.

 

[springtuck]

Re: Teleflex 7k tachometer

Just went through this with a fiara tach. 30 hp Johson 1999. Seemed to work fine in the drive way on muffs. At the lake it worked for about 10minutes. The rest of the day was spent alternating between 0 and pegged.
Back at the driveway, traced it to a bad diode pack. You may want to check the charging function. If the diodes are bad you will not be getting a good charge and the tach will do some funny things.

 

[jwellcraft]

Re: Teleflex 7k tachometer

Hi,

it is a 1994 Johnson 150 EXERV and yes the tach came set to 6p.

 

[ezeke]

Re: Teleflex 7k tachometer

You may have a failing rectifier; try moving the gray wire to the terminal block as described here: http://forums.iboats.com/showthread.php?t=190636

 

[jwellcraft]

Re: Teleflex 7k tachometer

I tried another quick test which invloved just checking the voltage at the signal pole at the tach and it read 7 volts at idle and as I increased throtlle it stayed there until it reached up around the 4,000 rmps and the voltage then jumped straight to 14 and tach dropped as usual. And this is another tach which the company replaced at no charge so I sent the first one back. Any suggestions?

 

[ezeke]

Re: Teleflex 7k tachometer

I tried another quick test which invloved just checking the voltage at the signal pole at the tach and it read 7 volts at idle and as I increased throtlle it stayed there until it reached up around the 4,000 rmps and the voltage then jumped straight to 14 and tach dropped as usual. And this is another tach which the company replaced at no charge so I sent the first one back. Any suggestions?

You are supposed to read +/- 3.5 volts AC at idle and +/- 5 to 7 volts AC at 2000 RPM. Be sure to have your multimeter set to AC voltage and read from gray wire at tachometer to a known good engine ground.

See #3 here: http://www.downloadingfiles.co.uk/teleflexfiles/gauges/Tachometers Outboards.pdf

BTW, don't run your engine above 1500 RPM with no load.

 

[jwellcraft]

Re: Teleflex 7k tachometer

I will double check but I am pretty sure I had everything set right. I only ran it up to 4,000 rmps a couple of times and no more than 3 seconds at a time and it was on the hose at all times. I didn't get any warning signals so I don't think I harmed anything.

 

[emdsapmgr]

Re: Teleflex 7k tachometer

Follow Ezeke's recommendation and check the rectifier/regulator. That's where the tach signal is generatated. When these go bad, tachs become erratic-just as yours is. Unlikely you have damaged anything.

 

[surrender]

Re: Teleflex 7k tachometer

You are supposed to read +/- 3.5 volts AC at idle and +/- 5 to 7 volts AC at 2000 RPM. Be sure to have your multimeter set to AC voltage and read from gray wire at tachometer to a known good engine ground.

See #3 here: http://www.downloadingfiles.co.uk/teleflexfiles/gauges/Tachometers Outboards.pdf

BTW, don't run your engine above 1500 RPM with no load.

On the 88 special is the resistor added because the ac voltage is different than what the above file calls for. My voltage is higher(14.7) at yellow/grey wire. It goes up with RPM increase. Waiting for new tack to see how it works. Old tack was bad, did other tests on it.

 

[jwellcraft]

Re: Teleflex 7k tachometer

Hey guys haven't tried any other tests yet but noticed the other day went I was out fishing as the tach approached the 4,000 rpm range my VHF starts alarming and saying excessive voltage. Why would that say that? I didn't think the VHF would have any wire connections to the motor or the tach.

 

[jwellcraft]

Re: Teleflex 7k tachometer

Changed the rectifier/regulator but haven't tested yet to see if it fixed the tach issue but as soon as I do I will post results.