85 308 QV Battery will not charge - can this cause no spark?

Once your motor is running, your alternator supplies a constant current to the battery. This is sufficient to cause spark. If fact, you can remove a battery from some running cars and they will continue to run perfectly.

However are you sure your plug is not firing? A misfire is normally quite obvious as the engine will sound abnormal and possible idle rougher.

Considering you have read information regarding this and your battery is dead, hopefully your problem will be solved with a new battery. Good luck and please share insight on how this could cause the problem!
-Cyrus

 

Excellent choice in battery. I have one installed in my vehicle and could not be happier. 3 year free replacement, 7 year pro-rate, full sealed, dry-cell battery for >$130? Can't beat it!
-Cyrus

 

Electrical problems can be soved by deduction. Since you have no spark on either side, the problem is most likely between the battery and the coils. Did you check your coil wires? When your battery went dead, it could have tripped something in your alarm. Some of them have two cutoffs. As you mentioned, you might just take it out to see if that's what's causing the problem. I'd start there.

 

most Clifford, Viper ect alarms i have had require you to hold the #1 button on the remote after a battery change, the alarm will go off or chirp, then" disarm" the alarm and see if it will start normally. talk to a local alarm installer about your alarm and see if you get order or download a manual for it, this may help you later since most alarm manuals have a wire diagram with the color code for what goes where and what does .... " what ". best wishes!
michael

oh yea a bad battery with low or too high a voltage can really screw up an alarm system and some highend stereo componets, its also not good for a computer controlled car either!!! dont ask me how i know!

 

Mike -- Do you have a copy of the schematic from the 307/84 OM?

If you really have no spark on both banks, the only "shared" things that could simultaneously affect both banks seem to be the power signals and the RPM sensor -- i.e., the rest of it is two completely independent systems. If fate was against you, I guess you could have both ignition ECUs fail or something in each system simultaneously fail, but I'd work on verifying the shared things first (if you really have no spark on both banks during cranking -- are you really, really sure?).

To check the power
Both coils will have two yellow (G) wires hooked to terminal 15 -- these lines should go +12V (relative to a chassis ground) during cranking.

To check the RPM sensor
IIRC others have reported that (when unplugged) the dc resistance across the two wires coming from the RPM sensor should be something like 700~800 Ohm. Alternatively (even though a multi-meter is not an oscilloscope), you could try making an AC (and/or a DC) voltage measurement across the two terminals of the RPM sensor (when plugged in and starter cranking) to see if you can detect anything during cranking. If you get "nothing", try looking at TDC sensors too -- if on all three you get "nothing" then you can't be sure that you're really measuring anything, but if you get "something" on the TDC sensors and "nothing" on the RPM sensor that would be a pretty strong clue IMO.

Let the madness begin...

 

Mike -- You didn't previously indicate that you had a modified ignition system on your QV so please disregard my previous post.

 

No offense but I had a lot of problems with my MSD, I think due to PO installation.

I threw it all away and went back stock. The tach works now!

 

"MSD" is usually translated as an aftermarket ignition box made specifically by the company MSD. If your system is "stock", you will have 2 ignition ECUs (one for each bank) which I think are in the rear trunk area on a 308QV -- wouldn't hurt to make sure they are dry, clean, reseat the connectors, etc..