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1990 70hp VRO tachometer

8

89 Bonito

New member
I recently bought a new sierra tachometer for my boat as it did not have one installed when I got it, when I go to crank the motor the tachometer reads while it's cranking but the moment it fires and the motor starts It drops to zero, I've tried idleing it up, changed the pulse setting and some other oddball stuff but alas, the same result. So as seeing I need to give answers to get answers I took some readings, all were taken on fluke 87 true RMS with the battery switch on and no other accessories running. Battery read 12.18 volts post to post

Gray to ground = 12.22v when key is on or when the motor is running
Purple to ground = 12.22v when key is on or when motor is running

key is off
gray to black = 12.18v
purple to black = 1.020v

Key is off
Gray to purple = .380v

also there is a 3 pin connecter in the motor that's not connected to anything that looks like the one for the tach, but it has a brown, black, and gray wire running to it, and there's also one standalone brown wire that's not connected, are these for the VRO pump, mines premix btw, any pointers to get me going in the right direction is appreciated
 
Purple should be 12V power when key is on.
Gray should be tach signal.

Where did you get those wires that you currently have plugged into the tach? If the wiring on the engine is connected properly you should have tach wires available at the engine controls that you can wire to the dash. On the back of the tach you should see a pulse setting dial. I believe that needs to be set to 6 pulse for your engine.

KJ
 
kevinj said:
Purple should be 12V power when key is on.
Gray should be tach signal.

Where did you get those wires that you currently have plugged into the tach? If the wiring on the engine is connected properly you should have tach wires available at the engine controls that you can wire to the dash. On the back of the tach you should see a pulse setting dial. I believe that needs to be set to 6 pulse for your engine.

KJ
Click to expand...

i think there might have been a mixup in the information, that last paragraph at the end about the 3 pin connecter in the engine was just another question and as far as I know isn't realeated to the tach,( should've started another thread for it) but I have the the connecter for the tach at the throttle and is where it's currently hooked up at. I read it needed to be at 6 pulses, just wanted to see if it would read on another setting
 
Also the purple key wire has 12.22v when running, with this could you rule out the key being an issue, I assume no pulse signal from the engine comes through the key, so that would leave you with just the gray signal wire, but that also reads 12.22v it's getting power, but is it signal issue?
 
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