chaseincats

Disconnecting the blue wire from the ignition box worked. Should we leave the other wires connected or remove the box in full? All wires except the blue are still connected and the car runs with the tach.

That's odd. Nope, standard L-jet is connected.

Gotcha - I'll give it a shot and let you know tomorrow if it works.

Wouldn't that disable the blue wire or would that just allow the tach to work without interference?

Hold on...what other module? I thought the transistor ignition box was in the passenger footwell. Is this something else? EDIT: fuse box not fusible links lol sorry, brain fart. Why would the car run with both connected but the tach wire being the final straw? Is disconnecting it as simple as unplugging the box or are there other wiring changes I'd need to do for that to work?

The tach adapter is used for an "erratic tach" only it seems. Since the tach isn't working at all and is killing the car I don't think we'd need that. I'll give the wire colors a look this weekend and report back. Regarding the blue wire, it's on there in the FSM for '75 tho:

I thought those were rivets but apparently they just stripped all the screws - great

If we can figure out how to open these things we absolutely would haha

I plugged in a different AFM without play in the arm and the problem went away. I was able to see the richness/leanness change due to the play in the swing assembly on my air fuel gauge. You can tune the car using an air fuel gauge by changing the tension in the AFM's spring after confirming your water temperature sensor is working properly. There was a thread on here with a very long adventure learning how to tune my car with that method.

Sorry if I'm not explaining this properly. If you open your afm cover you will see an assembly that turns right to left. The wiper arm is connected to a counter weight that is mounted to a pipe that goes laterally through the housing to which the flap inside the afm is connected. There is play in that entire assembly regardless of how tight you crank the black gear controlling the tension spring. I'm assuming inside the unit (on the side opposite the circuit board (toward the radiator) there is a bushing on which the rod pivots which is probably dead. I'm asking if there is a way to access and replace that bushing. I hope that makes more sense!

Any place specifically you know that would buy it? Beats sitting in my garage collecting dust.

Finally got a chance to check and it's losing spark.

Sorry, I meant the entire arm assembly as a unit (arm, weight, flap - that entire assembly has some forward/back (open/close of the flap) play.

Question for you - my friend's AFM's arm is loose in that you can wiggle it back and forth about a millimeter or two. Tuning the car with an AFM is obviously impossible since the resistor arm isn't getting consistent results. I'm guessing there's a bushing in there somewhere that went bad. Can these be opened up, and if so, are the bushings available?

I changed my motor to the kia one a few years ago and immediately noticed a difference in terms of fuse consumption. I went from changing them every couple weeks to every couple of months.

So the resistance created by the resistor in the fan case does not move backwards into the fuse?

I was under the impression that the fastest fan speed setting was the best for the car since it wouldn't be using the resistor in the big fan case under the dash (I dont remember what its called).

Sorry to bring this back up but did you ever find out what was causing this Dave? My fuse is getting pretty toasty too.

It isn’t, I’m guessing that’s part of the crane system.

We ended up cleaning the terminals on the dropping resistor and now the car idles really well. After the fact, we measured all of the injectors through the ECU connector and they all ready ~10.5v. I checked the dropping resistor power wires, the main power wire was battery voltage and the one on the top left was around 10.5v (same as the injectors). Not sure if that's how its supposed to be, but now it's idling well.

Hi guys, Working on my friend's 1975 280z and when you connect the blue tach sense wire to the negative terminal on the ignition coil, the car will stall (and also won't start if already connected). He has the Crane XR700 ignition system if that helps at all. When I connect the blue tach sense wire and crank the car, the tach will move meaning it is connected but won't start until you remove the wire. Any ideas what's going on here?

Sounds good. He is getting the car back today and will clean the terminals on the dropping resistor just in case. I'll let you know the results and take measurements next time I'm over.

Yeah, they were all off when we took measurements - we just went from one to the next. It did run WAY better after cycling them all but that was only temporary. My guess is cycling them in the cylinders so many times eventually got enough gas in each one for it to run properly. After that was burned off it did go back to running how it was prior to cycling them.

This is with the connector disconnected from the injector - literally touching the female connector pins with a multimeter that the injector's would plug into. We did confirm the the injectors work by using wire leads directly to a 9v battery with the connector disconnected. Injectors 1-4 that were now accustomed to the low voltage had a considerably fainter click than injectors 5-6 but after clicking them on and off 9v a few times, they began to come back to life and the audible volume of their 'click' gradually began to match injectors 5 & 6.

Good call - I'll relay the message.