no spark and the tach went out!

[point45]

The engine was idling but would occasionaly start to drop from about 950 rpm to around 550 rpm and the timing would jump around a little at idle.

Then suddenly the tach goes to zero and the engine sputters, dies and wont start now.

It will turn over and catch for a split second but thats it and the tach will dance while the engine is turning over.

the coil tests ok with resistance and if i unplug the center wire from the distributor it sparks nicely against the valve covers. But when i test the spark at the plug it is very weak or not there at all.

I just replaced the ballast resistor and ignition module with a new mopar orange 4 prong last month. The distributor is a remfurb from o'riley.

I think its something in the distributor but would this also cause the tach to give a zero reading.

[Chryco Psycho]

Try disconnectng the tach , it could be affecting to ability of the ign to create spark , other then that bad wires or moisture on the wires would be my next guess

[MEK-Dangerfield]

I agree with Chryco. Disconnect the tach first. I had one that worked, but there was some kind of internal short that was sucking the life out of my spark.

[dodj]

if i unplug the center wire from the distributor it sparks nicely against the valve covers. But when i test the spark at the plug it is very weak or not there at all.

The only common parts are in the distributor. If you have good spark at the centre coil wire (going in) but not at the end of the plug wires (going out), I would take a good look at the cap, rotor, etc

[point45]

unhooked the tach wire from the coil. Still nothing.

how do i check the distributor?

[dodj]

Well if the coil wire is sparking 'nicely against the valve covers' the pick-up/reluctor must be working so I would check/change the cap and rotor.

[Chryco Psycho]

It could be bad wires , the risistance should be around 7-18 thousand ohms
 or a weak coil

[point45]

Just finished swapping out the distributor with a new one from summit. Didnt completely trust the reman from o'reillys. So at this point the car has a whole new electrical system.

Fired right up and all is working as far as the ignition, also a much stronger spark than before but the tach is still dead. The needle jumps around when cranking but it dosent read RPM.

Thanks for all the help guys, i dont know how i would get through this car without you guys.

[mopardave]

problem i have had with this same issue is GROUNDING. the ECU on my wife bird and dads chall both have lost ground which will also affect the tach. If the tach doesnt move when cranking then that may be the issue. 

[point45]

I thought that might have been the initial issue with the loss of spark so i ran a ground wire from the block to the ecu. Also the tach does jump when cranking but is dead still once the engine is running.

Looks like im just going to have to get the multimeter out and start chasing wiring. Unless the tach actually is dead somehow.

[mopardave]

run the groung wire directly to the battery or a good chassic ground. the block may not be enough

[point45]

Just tried that and still nothing also checked all the wiring and it seems ok, no shorting out with ground.

I think the tach is just shot.

[point45]

Thanks for all the suggestions on the tach but im 99% sure its dead. Picked up a sunpro to test and keep for timing the engine and it runs just fine with the connections.

I guess i have that excuse to pick up that auto meter elite that ive been eyeballing.

Once again thanks for all the help guys.