Thread: Weird Tacho issue

When I start my car, the motor starts and the engine runs, but the Tacho doesn't move for the first say 7 or so seconds. Then it suddenly jumps up to idle rpm (+/- 1000rpm)

What could be causing this??

It concerns me cause I'm thinking there is no signal going from the dizzy to the ECU, which in turn means the fuel pump doesn't work either when the car is turning over and for those first few seconds.

Bad gauge, when mine went bad it would randomly work and not work.

If you weren't getting a signal to the pump and it wasn't working, you wouldn't be able to start your car. No pump to move fuel = no fuel = no start.

I guess I have to take a voltmeter and test this out, but I figure there is enough fuel in the lines to get the car started, and to let it run for say 10 seconds before the Tacho comes alive, and signal to the pump is restored.

If that's not the case, and the gauge cluster is simpy faulty then i'd be very happy. I am worried it's an issue between the dizzy, ecu and tacho. Cause that would suck.

I think you are over thinking this. Start with the basics like you said and measure at the cluster.

Oh forgot to mention (wanted to keep it short) that the car died on me a few weeks ago. Thought it was the fuel pump, as I didn't hear it pumping while the engine was cranking over. Pulled the lines and confirmed the fuel pump wasn't working.

Thought my pump failed, but then discovered I got no spark. Turns out the dizzy failed, hence no signal to ECU, hence no signal to fuel pump relay.

Changed the dizzy and everything was fine again. But noticed this issue with the tacho now being very consistent.

So I'm kinda wondering why the old dizzy died. The car had the same issue with the tacho when using the old dizzy, but just more intermittently. Like every second or third time I start it. Now the tacho does it on every start.