Coil only putting 9 volts???
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 751
Likes: 0
From: Eau Claire Wisconsin
Coil only putting 9 volts???
I just put a whole new MSD Opti in my 94 LT1 along with a new MSD Blaster coil. It still will not start, cranks great but no start or even an attempt to start. I have checked all the grounds, 12v leads and pulse signals. I took the ignition module off and had it tested twice and passed. I checked the coil for spark with the coil wire off the Opti and grounded to the ex. manifold...no spark. I hooked up my volt meter to the coil wire and grounded it at the same place and got a little over 9 volts I also tried the old coil that was still good and same thing. Help please
...........................THANK YOU!!!
-Mike
...........................THANK YOU!!!-Mike
Last edited by GS4-LT1; Aug 17, 2007 at 12:19 AM.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
9 volts is close to the minimum voltage to get fire from the coil...if your close to 9v trickle charge the battery back up to 12v or jump start the car....then try to crank it again. Did the car run before the new "MSD Blaster coil" was installed? Does the car try to fire at all with either coil? Why is the voltage so low on the car...have you checked for loose connections or corrosion on the terminals? Is the alternator still connected?
1. Check the fuse pannel to ensure that all fuses are still good.
2. Pull a spark plug .....attach it to ground to check for good spark...if spark is good move on to something else.
3. If the battery doesn't take a charge take it out and have it tested.
4. You may want to ohm your fuel injectors to see if there are open or shorted.
5. You should also get a fuel rail pressure gage and test to ensure that : the fuel pump runs; you have 40psi on the rail; test the leak down times for open injectors flooding the engine or internal tank leaks.
Good luck!
1. Check the fuse pannel to ensure that all fuses are still good.
2. Pull a spark plug .....attach it to ground to check for good spark...if spark is good move on to something else.
3. If the battery doesn't take a charge take it out and have it tested.
4. You may want to ohm your fuel injectors to see if there are open or shorted.
5. You should also get a fuel rail pressure gage and test to ensure that : the fuel pump runs; you have 40psi on the rail; test the leak down times for open injectors flooding the engine or internal tank leaks.
Good luck!
Melting Slicks
Joined: Jul 2006
Posts: 3,356
Likes: 1
From: Chesapeake Va
More info = more help.....
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
One wire on the spark coil primary goes to 12v with the ign sw in, "run". The other primary coil wire goes to the spark module which pulses this wire to ground to generate a spark. Put your voltmeter negative lead on the battery negative terminal and measure the voltage on the coil primary that goes to the ign sw. It should measure the same as the battery voltage which you should also measure. You can tell the state of charge by measuring the battery voltage no load. 12.0 volts and below, discharged. 12.9 volts and above, fully charged and linear in between. You can pulse 12v to the coil primary with a .05 Mfd to 0.1 Mfd capacitor across the primary winding and if your coil is good, the secondary will generate a nice fat, over 1/2 inch long spark. The spark module gets told when to pulse the coil primary to ground from the pickup coil pulses in the distributor (Opti). You may have a toasted Opti.
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 751
Likes: 0
From: Eau Claire Wisconsin
Yes, I was trying to fix a no start problem to begin with. Coolant poured all over the opti from the thermostat housing and would no fire after that. I let it dry for a few days and still nothing. After everything I have heard about the opti system I decided that had to be it. If the new opti is somehow fried it would throw a code. I have checked for codes with the jumper wire and the system is free of codes. I have a multimeter and have access to a Snap-On scroll scanner. The battery is fully charged and everything else works. Just no spark. Any ideas, please. I do not want to have it towed to the dealership.
-Mike
-Mike
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