Difference in tachometers?

[EHardgrave]

Is there a difference between a 1991 Johnson tach. and the newer ones? In our conversion from 91 to 02 we are not getting a tach signal. We tapped off of a gray wire in the new harness and ran it to the old tach and nothing happens. Did the older 2 stroke have a more powerful signal than the new 4 stroke EFI does? Also is it normal for the tach to rest at 2500 when the key is turned off and drop to 0 when at turned on?

 

[EHardgrave]

Re: Difference in tachometers?

I looked at the back of the tach and it is at 6p. Is there a different setting for the new 4 stroke motor?

 

[marinemech1]

Re: Difference in tachometers?

the tachs are the same<br />did you install a system check gauge?<br />tach should have gray-signal purple-power black-ground installed<br />tach needle will move when key is turned off<br />6 p is correct setting

 

[EHardgrave]

Re: Difference in tachometers?

We are converting from a 1991 2 stroke to this new 2002 4 stroke with the system check. We have a harness converter that goes from the red round plug to the different shaped ones on the newer motor. Anyway the harness that runs up to the dash only has a 8 pin connector and a 2 pin connector. The 8 pin runs to the 2" system check gauge with 4 led’s on it. The 2 pin to a buzzer. We had the orig. gray wire to the tach and nothing. Then we tapped off the new gray wire that actually runs into the 8 pin plug. Nothing there either. Are there ay tests to see if the gray wire is sending what it should?

 

[readyakira]

Re: Difference in tachometers?

Have you noticed if the tach jumps at all when you turn the key on. If the needle doesn't move at all it may not be a signal problem but a power to the tach prob.

 

[EHardgrave]

Re: Difference in tachometers?

Yeah we tested the purple wire with meter and it is hot when ignition is turned on. I just didn’t know if the tach needed to be different since the signal from the motor is coming from the ecu on a 4 stroke with efi?<br />Yes we have installed the system check gauge. Just the LED one not the tach one.

 

[EHardgrave]

Re: Difference in tachometers?

Maybe we should have gotten the tach with sys check built in. Only problem is the hole has been drilled in the dash already for the 2" sys check gauge.<br />What kind of voltage (DC) should I see from the sending wire?<br />Is there anyone out there who has successfully converted from 1991(or close) wiring to 2002 with sys check using harness adapters?

 

[EHardgrave]

Re: Difference in tachometers?

Does anyone know if just the tach sending part of the ECU can be bad but the rest of it be ok?

 

[marinemech1]

Re: Difference in tachometers?

ecu could be faulty or another sensor<br />you need a peak reading volt meter to measure gray wire out put

 

[EHardgrave]

Re: Difference in tachometers?

What kind of reading should it have if I can get one of those?

 

[marinemech1]

Re: Difference in tachometers?

i can't remember exactly??? but it should be around 8 volts and higher i think \<br />have you tried a different tach??

 

[EHardgrave]

Re: Difference in tachometers?

Only tach we have around is a auto. I didn't think that would do. I might check with our only boat mechanic here in town and see if he has any we could borrow for testing. Thanks for the help. This has been so frustrating. As soon as we figure one issue out another shows up. Trying to save some money on the conversion.

 

[EHardgrave]

Re: Difference in tachometers?

We took the tach out last night. It says for a alternator motor. Does it matter that ours doesn't have one. Could the regulator maybe be bad and not be giving a signal. We used the auto tach last night and got it to work. (seemed high though). I assume this means the regulator is working. Should I still check that it is charging ok?

 

[marinemech1]

Re: Difference in tachometers?

i think the ecu controls or supplies the tach signal i could be wrong