Last night I had to ge tmy car started after it not running for almost a month if not longer. Well, I ended up atf ing it and she finally started but immedeatly(sic) after she fired up, the tach just quit. I watched it show about 2500 rpm for a second (had my foot on the throttle) and then it dropped right back to zero. Anyone have any insight on what might have happened? I think the crank tigger or maybe the tach pick up itself just decided to burn out, though I dunno.

 

Start it back up, the tach should work just fine.

2nd Amendment...

When your RX-7 floods and you try to unflood it by pulling the EGI fuse, sometimes the tach stops working after you put the fuse back in. The tach will refuse to budge until you turn off, wait a few minutes and then restart the car. I don't know why it does this, but its just one of those things.

 

Thanks Zach. I'll double check it when I go to the shop later.

 

if the crank angle (CAS) failed the car wouldn't run. It has nothing to do with the tach signal.

The tach signal comes from the trailing coil. If the tach is dead, the trailing coils are not firing or there is a loose or bad connection between the trailing coils and the cluster.

 

I had my tach die when I had my cluth replaced. There is a 14G wire that goes from the firewall to the top of the tranny where it bolts to the engine next to the engine hoist bracket. Check that......Also check the trailing coil, making sure that the ground from the coil is still godd. It is kinda buried, and crud likes to gather down there hindering ground.

 

If you find out you do need a trailing coil, I have one for sale. PM me if you need it.

 

Zach, you were right. Thank you again.
Icemark, thank you for correcting me, I am always happy when someone can correct something I've incorrectly stated.