Upgraded Ignition System Startup

After reading numerous Jeep Hammer posts on JEEP FORUM regarding ignition upgrades applicable to my stock 1975 CJ5 I6 258, I replaced the Prestolite distributor and ignition with a Ford DuraSpark Motorcraft distributor and a used MSD 6A module I purchased off of EBay. I also did the TeamRush upgrade, MSD wires, new plugs gapped at .045, etc. I am confident that I set the distributor correctly by finding the compression stroke TDC. The distributor dropped right in (after a couple of hand rotations of the crank shaft) with the vacuum advance angled toward the front of the engine block and the rotor pointed directly at the vacuum advance pivot point. I kept the original coil for now and only the orange and black wires are connected from the MSD. The MSD small red wire is connected to a red wire coming from the ignition switch and the heavy red and black are directly connected to the battery. The jeep was running fairly well prior to the upgrade. At the startup, I may have made a really bad mistake. I somehow failed to reconnect the negative side of the battery back prior to cranking it the first time. Sensing the weak start I figured out the error and connected the negative battery cable. On the second, third, and fourth tries, the engine would fire, run for a few seconds and die. It had a very strong gas smell like it was flooded. I'm not sure what my next steps are but I'm definitely all ears.

 

Are you using the Ford Duraspark with the magnetic pick-up?

 

Are you positive the used MSD was working?

In your Duraspark did you go with the larger cap?

Lastly, is your old coil working? I assume its the oil can variety. (You may want to go With the wound coil at a later date to help wake it up).


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Norm

 

Thanks guys. I misspoke about the Duraspark. I used a Ford distributor that was common on JEEP 258's starting around 1978. I am running it with an MSD CDI Module with magnetic pick-up (I think). I believe i have the small red wire from the MSD module wired incorrectly.
Below is a pic of the coil as i was disconnecting the Prestolite wires. The Yellow, Green, and Black wires were all connected back to the gold Prestolite box. The double red wires come out of the main wiring harness. I assume this is maybe the starter relay? Whatever it is, i connected the MSD red wire to this set of red wires, but did NOT reconnect them to the coil based on the MSD directions. I have only the orange and black wires from the MSD currently on the coil. I have my fingers crossed that getting the little red wire in the right location will solve it.

 

Running for a few seconds suggests the connection from the ignition switch is hooked to the "start" position, not the "run" position. Or the ballast resistor on the coil has failed. This would result in the coil getting power only while cranking.

 

Not sure what the confusion is about the Duraspark. The Ford Motorcraft distributor from a Jeep is a "Duraspark I" distributor. Jeep used the "Duraspark I" (originally known as just Duraspark). There was a Duraspark II, which has the big cap and TFI coil. This is the same distributor body and internals, with the big cap, TFI EI-style coil, and a different TFI module that can run with no ballast resistor, like the HEI. Basically you are mixing and matching the Duraspark and Duraspark II components here.

IMO running for more than a few seconds and less than a few minutes points right at the MSD module.

You can buy an import GM HEI 5-pin module for about $10 at your local FLAPS, and it will be a functional replacement to the MSD. This will let you test your used (!) MSD module by subbing a known good component. For wiring, check the 'net for "stealth HEI" for Jeep.

It's really important how long the engine runs. If it starts and then dies when you release the key from start to run, you have it wired wrong. With the key on but not turned to start, there should be power to the MSD module. There is also a white wire (?) on the MSD module that cannot be grounded (?? something like that) or the engine will die.

You need to check your wiring and make sure that the MSD module gets power when the key is simply on ... running or not running should not matter. You also need to make sure that the MSD wires are connected correctly. You can go to Summit Racing and look up your module - they put the module instructions there with the product. MSD has detailed instructions for connecting the module with nearly every possible type of ignition and triggering.

 

Also make sure the MSD is getting a full 12 volts not going through the ballast resistor with the ignition switch on. BTDT

 

Thanks guys. I really appreciate the advice. I've looked through the MSD wiring diagrams and still am having trouble figuring out where the "small eyed wire" from the MSD should connect. I know it provides the power to turn on the Module. As a test, I temporarily connected it directly to the battery and tried to start it. It was about the same and would run just a few seconds after letting go of the ignition key. Any idea where I would take the MSD Module to have it checked out? I may try a HEI module as a test as well. The small white wire that should be with the Module seems to be missing or cut off - I'll need to investigate that further.

 

Today I got a chance to do some testing and double checking. I reconfirmed TDC on the compression stroke. Also found some MSD instructions to test the module via inducing sparks at the coil cable. Per the instructions the module should be good. I also tested the voltage at the jeep wire that I had the small red MSD wire connected and it has the needed 12v with the key in the "on" position. Lastly, I tested the resistance of my coil. On the primary side it had 1.8 ohms. This is within the original factor range of 1.0 to 2.0 ohms, however, an MSD Blaster coils is at .70 ohms.....seems like a big difference and I wonder if that could be the issue. The secondary resistance measured 7800 ohms. The TSM calls for 8,000 to 12,000 ohms. A new Blaster 2 has 4,500 ohms. This all makes me wonder if the original stock coil is compatible with the MSD ignition.

 

Mmm. The factory coil should work fine with the MSD module. The resonant LC circuit with the MSD module will amplify the spark significantly - IMO a hot coil plus the module is overkill for Jeep applications. However, that does not rule out that you have an intermittent coil failure. A spare coil is a good thing to have... BTDT.

Second, low resistances are very difficult to measure accurately with inexpensive equipment. I would not expect better than +/- 100% accuracy from your multimeter down around one ohm. A functional test should be much more telling, sp. color and intensity of the spark.

If you have a ballast resistor, it is there to protect the coil and module from overheating. Its function is to current-limit the circuit so that the power dissipation in the coil and module are not exceeded. The MSD module can probably be connected without a ballast resistor - check the instructions - but the extra resistance in the coil circuit will not prevent the spark discharge from operating.

 

Thank you Timgr. Do you happen to know if the 75 model has a ballast resister? I can check my TSM but I don't recall seeing anything.....on the other hand I don't know what they look like.

 

Looking at the wiring diagram, it appears that there is no ballast resistor. And it uses a conventional coil, so the module must current-limit some how.

If there were a ballast resistor, it would be a resistance wire. The Duraspark ignition form '78 and later has one, and it's clearly labeled on the wiring diagram.

 

Correct. No ballast resistor and no special resistive wire. Those two red w tracer wires going to the positive terminal of the coil will be one going to the ECU and the other to the dash for the tac. If you don't have a tachometer, the wire will be in the loom from factory but just hanging loose under the dash.

 

Just to clear about what is occurring, the engine starts up immediately then i get a little carb backfire and it dies about five seconds after it starts. It's still a mystery to me why it won't run. Especially since it was running fairly well before the upgrade. Too much resistance on the old coil is the only thing I can come up with but I do respect Timgr thoughts on that. The only other thing I can think of is that I may have too much dielectric grease in the spark plug boot but I can hear the plug boot snap onto the spark plug.

 

Gigem1983, I went back to reread this thread and noticed something. In post #4 you have a pic of the dist and plug wires. I noticed that on the center plug wire of the pic, there is what looks like three lines made with a marker on the wire, (which I assume indicates which cylinder it go,s to) that wire is connected to the #4 tower on the dist. I would recheck your wires, it would be nice if that's all it turns out to be. Something I am confused on, is that in your first post you state that the rotor is pointing directly at the vac advance pivot point. If I havnt misunderstood what I read, the rotor should be pointing to the #1 plug tower, not to the vac can.

 

Thanks Jeepcj. The wires are correct. Those three marks not related to the cylinder number. The rotor pointed at the vac advance pivot point is per this photo off another forum. [/URL][/IMG]
This is to help with getting the dizzy stabbed in the right location. When I put the cap on the number one tower aligns with the rotor also.

Today, I verified that I am getting spark at every wire and cleaned off some of the dielectric grease in the boot and spark plug head.

I also turned the dizzy counter clockwise as far as it would go before the vac advance hit the block. From there I CAN GET IT TO RUN AS LONG AS I CONTINUE TO PUMP THE GAS. That makes me wonder if I need to restab the distributor to allow me to give it more counterclockwise turn. Does this rule out anything I.e. bad module or need to restab distributor?

 

The module is either go or no-go. The back-fire up thru the carb sez out of time.

 

Are you saying that because it is getting fire that the module is likely good and I should focus on the timing?

 

I agree - look at the timing.

You could try reversing the polarity of the sense coil to the module. You could be triggering on the falling edge rather than the rising edge of the signal, or vice-versa, depending on what it should be. This would change the timing.

Look here - http://www.megamanual.com/ms2/pickups.htm

Both the GM HEI and the Duraspark are VR sensors.

With points ignition, you can static time the engine before it is running. I don't know if you can do that with the MSD - maybe. Check the instructions for setting initial timing.

 

Not sure it matters , but shouldn't the vacuum advance be pointing more towards the pass. fender ?