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-   -   Tachometer dead after engine drop (?) (http://forums.pelicanparts.com/porsche-911-technical-forum/837924-tachometer-dead-after-engine-drop.html)

gjmascoli 11-09-2014 05:10 PM

Tachometer dead after engine drop (?)
 
Finally got the engine running again after my first engine drop but now the tach is dead. I seemed to be getting a signal when I was cranking the engine to build oil pressure prior to starting for the first time, but now that she has fired up - no tach.

Any ideas where to start trouble shooting?

timmy2 11-09-2014 05:48 PM

Tachometer dead after engine drop (?)
 
Signal wire connected at the white "T"connector below the CDI?
Wire comes from points to T connector with red wire sending tach signal to tach.

gjmascoli 11-09-2014 06:33 PM

Ah ha. Thanks for the tip on where to find the signal wire. It is connected, but it also appears to be loosely wrapped with electrical tape at the "t". I was having trouble getting the engine to fire and realized that I had the timing 180deg out of phase. I pulled the distributor without disconnecting the signal wire, and perhaps I've stressed the connection.

I'd mess with it now, but it's late, my kid's bedroom is above the garage, and the engine is really loud!

I'll check it tomorrow morning, but if anyone has other ideas, I'm still open.

Thanks

gjmascoli 11-10-2014 04:33 PM

Oh well, messed with the white "t" wiring and fired up the engine but no dice, still no tach.

A couple notes:
1) Car has blue Perma-tune unit, this was an upgrade long ago by a PO;
2) the tach gives a little blip when the engine initially fires up, but then no life afterward.

Any leads will be of help.
Thanks

scarceller 11-10-2014 04:43 PM

Can you test the tach in another car? Tach could be bad.
Also check the ground wires on the back of the tach, be sure they are clean.
And fully charge the battery. I've seen tachs not work if battery is low.

gjmascoli 11-10-2014 05:24 PM

I can't test the tach in another car. It was working fine last year prior to the engine drop. The battery is brand new, but it did get a good workout as I cranked the engine for a total of about 2-3 minutes (30 second intervals) to prime the engine with oil, so maybe a low battery.

Engine fires up instantaneously, so I'm not noticing any weakness in the battery.

The only good news I have so far is the instantaneous start. The engine used to take quite a bit of finessing to get it to start and idle smoothly when cold. Now I have a powerful start-up, just no tach :-(

timmy2 11-10-2014 05:35 PM

Just to clarify my earlier post.
The red wire in the T connector is the switched power to the CDI on an original 3 wire CDI setup.
The other wire with the red wire in the connector should be the tach signal wire from the points on the ''73.5-'77 ignition wiring.

gjmascoli 11-10-2014 06:13 PM

Here's my connections. Sorry about the upside-down pix
http://forums.pelicanparts.com/uploa...1415675499.jpg
http://forums.pelicanparts.com/uploa...1415675551.jpg

gjmascoli 11-12-2014 05:58 PM

Still dead.

What next? Check Voltages? How?

timmy2 11-12-2014 06:49 PM

Show us what is under the tape where the white T connector is.

gjmascoli 11-13-2014 05:04 PM

Pulled the tape off. The plastic insulation was broken, but the wire is intact and connected

http://forums.pelicanparts.com/uploa...1415930617.jpg

gjmascoli 11-17-2014 05:27 AM

Drove about 35 miles this weekend.

No tach, but a distinct blip on the tach needle at start up and power off. So the tach appears to get something. but the needle is dead as a doornail when the engine is running.

I guess my next step is to pull the tach out. Any tricks I need to be aware of, I don't want to damage anything (cosmetically, electrically, or mechanically)


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