After finishing up my swap to a turbo 13b into an FC the rpms only show up to 1000 rpm and then drop back down to zero.

The tach always worked before so my first guess is that it is some sort of sensor. All other gauges appear to be working but I haven't actually driven the car so I can't say the speedo is working for sure.

When I rev the car it shows up to 1000 rpm and when the rpm is above that the gauge just drops to zero. As the rpms drop to the 0-1000 rpm range it start to show again on the gauge.

Anyone have an idea what steps I should be taking to solve this?

Thanks

 

The tach is wired to the Yellow/Blue wire of the trailing coil. Perhaps that coil is problematic. There are bullet check connectors at each coil. It's just a single wire w/a tube connector at the end connected to nothing. If you bridge/jumper these two wires to each other the tach would then run off of the lead coil.

 

Thanks a lot that's really good to hear. My t1 on the trailing coil is faulty and I've already ordered a replacement. I didnt know the tach problem was also linked to it. I will try that out in the mean time just to see if the tach starts working again.

 

The new ignition coil hasn't come in yet but I jumped the two bullet connectors and the rpms are showing up. Thanks again

 

I installed the new (used) trailing coil and am getting a spark from both T1 and T2. I'm fairly sure that the tachometer was working at first (without the jumper installed) but then soon after it stopped and I had to add the jumper wire to the bullet connectors between the two coils in order to get any reading on the tachometer again.

If the coil pack is producing sparks then why am i not reading rpms without the jumper wire?Checked again and the trailing coil is still producing sparks on T1 and T2.

Thought that the issue may be related to timing and had quite a day researching how to mark the timing position on the eccentric pulley since mine did not have a marking and was swapped from my original engine. Once I got that marked on I checked the timing and it was fine. I can't get the engine to idle either so that is the other reason I was doing this.

 

The Yellow/Blue wire at the trailing coil sends the signal to the tach so that is where you should devote your time to. Clean the plug w/this wire and make sure it's making good contact.

 

Thanks Satch I'll give it a shot