tach issues

[brian3127]

The boat has a tach and it workded before i decided to rebuilt the boat I never put it back on I want to put it back on what wires do I hook it to. The wire colors I have are
Red with purple stripe
White
Purple with white stripe
Blue with white stripe
Blue
Black that jumps from the key to the electric choke

the motor is a johnson 40EL75C

i have read on this site that you need a grey wire. i dont have a grey wire under the dash. i might have pulled wires out that i didnt need when i redid the wiring not thinking that some of them are important. so this grey wire that im supposed to have where would that hook to on the motor so i can run another grey wire up to the dash.


thanks

 

[TrueNorthist]

Re: tach issues

On my 70 the gray tach wire from the remote goes to the terminal block where it changes colour to Brown/Orange 18ga then into the timing base. Might be the same on the 2 cylinder? Have a look at the harness connector and see if there is a stub of gray wire still there and splice to that. The wire will be gray on both sides of the connector. You can also tace from the Brown/Orange wire to the terminal block and on to the connector.

 

[brian3127]

Re: tach issues

i will take a look at it today when i get out of work

 

[brian3127]

Re: tach issues

I bought a manual for my motor today. I turned to the page that shows my motor diagram and in the legend it show that a grey wire is shown as a bunch of circles (00000000000000) but it doesn't show that wire in the diagram. So I looked at the block where all the wires are screwed into and found a yellow wire with a grey stripe. So I ran a wire from that connection to the tach and the ground to ground. The tach jumped to 4000 rpm. ( thinking that's not right) there is a setting on the back of the tach. By turning a screw to how many pulses per revolution. ( which is 2 because it is a 2 cylinder motor) then it dropped to 2000. The motor didn't sound like it was running at 2000 rpm. It sound slower than that so I'm wondering if the tach is wired correctly or if the tach is malfunctioning. When I throttled up the needle rpms went up and when I throttled back they went down. I don't know maybe I'm wrong and it was running at 2000. I want to get it right because I'm having problems with the motor not running right and I want. To get the motor running at about 750 at idle and the only way to do that is if the tach is wired correctly. The motor doesn't want to run very well at idle it always stalls so I'm wondering if I'm trying to set the idle to slow and it's not going to run.

 

[metriccrescentwrench]

Re: tach issues

By turning a screw to how many pulses per revolution. ( which is 2 because it is a 2 cylinder motor)

NO!!!!!! That setting depends on how many magnets are on the flywheel (each time a magnet goes past a coil in the stator you get a pulse). I don't know what it should be for your engine, but on the 3 OMC's I've had it's 6.

 

[brian3127]

Re: tach issues

NO!!!!!! That setting depends on how many magnets are on the flywheel (each time a magnet goes past a coil in the stator you get a pulse). I don't know what it should be for your engine, but on the 3 OMC's I've had it's 6.

Man I love this forum great information for people like me. Thanks Metriccrescentwrench I really appreciate your help. I have been getting frustrated with this motor issue and u put me one step closer to getting my problem solved thanks a lot. I will change it to six and try that when I get back to the boat probably Saturday. I have a family thing tomorrow. I will let you know the out come.

 

[brian3127]

Re: tach issues

Hey metriccresentwrench it was the problem it set it to six pulses and now it's right thank again