1997 Challenger not getting spark.

[A.J.C.]

Final Update!

Alright guys, with all the troubleshooting I did, the only thing left to do was to swap out the mpem. Since I didn't want to spend $700 plus on a used mpem, I ordered the MSD 4255 from Summit Racing for $350 with free shipping. It completely replaces the mpem. The only downside is I lose the security dess key. I have not tried to hook up the gauges yet but I think they will work. Anyway, with it all wired in, I finally have spark!!! Yay. Now I can finally move onto the fuel system and seal kit for the drive shaft. Thanks for the help Griz!

Here is how the MSD box sits on the plate. I will update with pictures of it installed in the boat after I am finished.

UPDATE!!!!
Will a bad rectifier cause no spark issue??? I couldn't see the conidition of this because its located directly underneath the starter solenoid? Its burned to crap! I really hope this is it! What would cause this?

I have been researching the topic for days now. I have another thread on here showing the progress of my 97' Challenger restoration.

I have the single 787 engine and it is giving no spark to the plugs. Let me list the things I have tested so far to help you guys narrow down what it could be. I'm keeping my fingers crossed that its not the mpem.

Brand new battery, and battery cables. Motor turns over great.

I removed the stator. The pick up coil mount is intact and I see no burn or dark marks on the windings. The pick up tests good. Its at a steady 242 ohms.

When I put the dess lanyard in, it beeps twice. If I press the start/ stop button 5 times with the key removed, I get a short and long beep. This tells me the dess is communicating with the mpem.

I checked the white with green stripe wire that goes from the mpem to the coil and am not getting a pulse signal when I turn the motor over. Its my understanding that cdi is built into the mpem on my boat.

I tested the coil, it measures .8 ohms which is not quite in spec but still should produce a spark.

The previous owner at some point spliced a new plug on that goes to the stator cover plug. The Black wire that pins out to the ground on the stator was melted all the way to the point where he spliced in to the harness. Also, those connections are pretty corroded.

Today, I'm going to make sure all those wires are spliced in correctly and redo all the crimps as well as replace the melted wire.

Do you guys have any ideas to why that black wire would be melted and could that be the reason my coil is not getting the pulse signal?

Sorry for the long winded post but I wanted to be as thorough as possible.

Thanks!

 

[A.J.C.]

Side note: The rectifier/ regulator, where is it located on my boat? I can't seem to locate it and am trying to see if the previous owner bypassed it or if its located in the ebox.

Here are pictures of what I'm working with.

 

[griz400]

your boat, chould have a module, called a dc-cdi module, The DC-CDI module receives the input from
trigger coil and signals the ignition coil when to
fire. It also has the rev limiter function built into its
circuitry, as well as the ignition timing curve. The
DC-CDI module is mounted in the electrical box --- also you have a trigger coil along with the stator that u shown in the picture,

also those pictures of your wiring --- cut out all them connectors and solder together using heat shrink as an isulator -- you must run on fresh water, cuse with those connections in salt water, it wouldnt last longer than like 3 days boating

also you do have an external regulator, just charging, and you have various fuses to check, in electrical box and check fuses at mpem

 

[A.J.C.]

I appreciate the help. I have a manual for the boat. The problem is, I bought the boat cheap with a bad motor. The previous owner took the motor out, hacked up the wiring, etc. I'm starting to think he bypassed the rectifier and if he did, I'm not sure if that could fry the portion of the mpem that sends out spark. I don't see a separate cdi box, I'm thinking its built into the mpem or I'm missing it. The diagrams in the manual don't really help because I don't know what certain things look like ( like the cdi, rectifier, etc.).

 

[griz400]

sorry, on a 97 , the dc-cdi is inside the mpem ,

 

[griz400]

also, the electrical box, those black caps have fuses under them

 

[A.J.C.]

All the fuses are good. I took them out and tested them. Here is a weird thing I found out testing electrical connections. If I disconnect the negative battery wire that runs to the mpem ground, but leave the negative wire hooked up to the battery that runs to the block, the mpem is grounded still and the boat will still turn over. Does this sound correct? It sounds like the mpem is grounding out somehow even though its not hooked up to anything other than the stator.

By the way, I found the rectifier, it is located underneath the starter solenoid.

 

[griz400]

i would check and clean all grounds, and definately repair those wires you have a pic of, just cut em out, and twist them for now, till you get spark, that way you know its all correct, then solder up

 

[A.J.C.]

I cut all those connectors out, replaced the melted wire, and resoldered and heat shrinked. Still no spark. Its kinda strange that the wires going into those connectors are different colors. I really hate cleaning up someone elses unfinished project.

 

[griz400]

test the wire back to the mpem from the pickup coil, it has to see a pulse when turning engine over, test it like you tested the wire to the coil you said in post #1, if mpem isnt getting a pulse back from the pickup coil, then it doesnt know engine is turning over, and it woulndt send a pulse to coil to fire the plugs

 

[A.J.C.]

Yes, I believe I'm getting a pulse from the pickup coil. I used the lowest voltage setting on my multimeter and it increased and decreased rapidly as I turned over the motor. It seems like its either a wiring issue or bad mpem.

UPDATE!!!!
Will a bad rectifier cause no spark issue??? I couldn't see the conidition of this because its located directly underneath the starter solenoid? Its burned to crap! I really hope this is it! What would cause this?

 

[griz400]

its definately burnt, unplug it and test and see if your getting spark ....

 

[A.J.C.]

I ordered a new one. I don't want to really hook anything up until I get the new rectifier. I just wanted to see if this will cause no spark.


I tested for spark with the rectifier unplugged and still did not get spark. I got +/- .3 volts out of the white wire that connects to the coil. With the white wire unplugged from the coil, i got 0 volts, well my mutlimeter read -0.00. usually it just says 0 when there are no volts.

 

[A.J.C.]

What should be the voltage coming out of the three yellow wires coming out of the stator while cranking the engine with the
starter?

 

[A.J.C.]

Alright guys, with all the troubleshooting I did, the only thing left to do was to swap out the mpem. Since I didn't want to spend $700 plus on a used mpem, I ordered the MSD 4255 from Summit Racing for $350 with free shipping. It completely replaces the mpem. The only downside is I lose the security dess key. I have not tried to hook up the gauges yet but I think they will work. Anyway, with it all wired in, I finally have spark!!! Yay. Now I can finally move onto the fuel system and seal kit for the drive shaft. Thanks for the help Griz!

Here is how the MSD box sits on the plate. I will update with pictures of it installed in the boat after I am finished.

 

[Eric in Ohio]

AJC, I'm a new guy here but I am having the same problem with my 96 Challenger. No spark. I see there are no further posts to this thread since March, Did the aftermarket MPEM do the trick? How are you running? Would you recommend this MPEM/Manufacturer/supplier ?

 

[xc700cet]

I'm new here as well. I too am curious if this worked as I'm in the market for a new MPEM for the very same boat. Any advice would be great!

 

[xc700cet]

Did you find out if the aftermarket MPEM did the trick?

 

[IDoSeaDoo]

I know that if you disconnect the rectifier red wire, the boat will run just fine. no idea about the aftermarket mpem. I really hate when people don't conclude their threads when they discover the solution...

 

[xc700cet]

Still no spark...

I know that if you disconnect the rectifier red wire, the boat will run just fine. no idea about the aftermarket mpem. I really hate when people don't conclude their threads when they discover the solution...

Frustrated... Unplugged red rectifier wire & same results. Gosh, I do surely hope he concludes his thread SOON! PLEASE?