1997 Challenger no spark HELP! MPEM?

[hasun100]

Hello

I picked up a 1997 Challenger single 787 engine. I am not getting spark on both plugs, changed stator to new OEM one as well as used coil pack pulled from a working machine, no change. Checked ohm values from service manual on: pickup coil (voltages 0.5v), stator, ignition coil pack & cables, all look good.

MPEM beeps twice when I plug the Dess in and engine cranks no problem. I am starting to think it could be MPEM, any way to confirm this? I see the white cable that goes from MPEM to coil pack and it showed me voltages all over the place, how do I test and confirm that its sending signal? Could it be a failed CDI? which is built in to MPEM on these years. Or maybe the pickup coil isn't functioning correctly even though readings look good?

If it is the MPEM, any aftermarket solutions? Would like to get engine running before winter
Any help is appreciated guys!

 

[POPPS]

Did you check out the trigger pickup coil.,,,it sends the signal to the cdi,,,not the stator,,it just charges the battery

 

[hasun100]

Did you check out the trigger pickup coil.,,,it sends the signal to the cdi,,,not the stator,,it just charges the battery

Yes, it has low voltage and resistance seems good.

 

[hasun100]

Did you check out the trigger pickup coil.,,,it sends the signal to the cdi,,,not the stator,,it just charges the battery

I check it going to the conputer, green black cable

 

[1983]

I am more familiar with the Seadoo jet skis rather than boats, but I am parting out the exact boat you have. PM if you need any parts or the MPEM or anything. I ship daily.

 

[hasun100]

I am more familiar with the Seadoo jet skis rather than boats, but I am parting out the exact boat you have. PM if you need any parts or the MPEM or anything. I ship daily.

Hey man, can you send me a pm, cant seem to find the pm option new here. Definitely interested in some parts.

 

[1983]

PM replied.

 

[wayneh]

Probably not relevant here but you won't get spark if the battery voltage drops below about 9V while cranking. In my experience it can crank nearly normally with an ailing battery, but it'll never start because the MPEM shuts down. It's a very easy thing to check, worth a look I'd say.

 

[mezzatt]

Hello

I picked up a 1997 Challenger single 787 engine. I am not getting spark on both plugs, changed stator to new OEM one as well as used coil pack pulled from a working machine, no change. Checked ohm values from service manual on: pickup coil (voltages 0.5v), stator, ignition coil pack & cables, all look good.

MPEM beeps twice when I plug the Dess in and engine cranks no problem. I am starting to think it could be MPEM, any way to confirm this? I see the white cable that goes from MPEM to coil pack and it showed me voltages all over the place, how do I test and confirm that its sending signal? Could it be a failed CDI? which is built in to MPEM on these years. Or maybe the pickup coil isn't functioning correctly even though readings look good?

If it is the MPEM, any aftermarket solutions? Would like to get engine running before winter
Any help is appreciated guys!

Hi, I’m new to the forum and I wanted to join to share some information that I found while fixing a 97 challenger single 787 for a good friend.

This boat has the CDI ignition built into the MPEM. I had the engine rebuilt and put all new parts in the stater container because there was water in there and destroyed the stater and the pick up coil. Tried to fire up the engine after getting it all put back in the boat, and it wouldn’t fire no spark.

Looked in the manual and found the ohms value so I checked the pick up coil and found that it ohmed out correctly and I assumed it was good because it was brand-new but you never know it could’ve been DOA. I also checked the voltage coming out of it at cranking speed and I got about six Foltz Peak to Peak on my oscilloscope. You could try to do this with a digital voltmeter, but it probably wouldn’t register very much because of the speed of the signal. Signal coming out of the coil is an AC signal not DC.

Appeared to me that the CDI, part of the MPEM had failed. tracing the wires back from the ignition coil. I found the lower left-hand corner of the MPEM is where the CDI ignition module circuitry is located.

I decided to cut the bottom side of the unit because I wanted to make sure that I wouldn’t accidentally damage parts on the top side, trying to do an archaeologists dig.

I tracked it down to a bad silicon, controlled rectifier, SCR, part number MCR72-6GOS-ND (digikey). Soldered that in place from the bottom of the board, tested the module out before repotting it and then I used Permatex, gray gasket sealer from AutoZone to repot the Electronics so that if I had to get back into it, it would be easily removed in the future.

I’ve included pictures of the front and back before, and after as an added to all the rest of you.

I’m not super good with video editing, so I’m just going to tell you that in the picture below there are three semi conductors in the photo.
The semi conductor in the very top of the photo is the silicon controlled rectifier that fires the CDI ignition.

The second semiconductor, which would be in the lower left, is a transistor used to engage the starter solenoid external to the MPEM module. The last semiconductor, which is a smaller to the lower, right I didn’t get a chance to figure out what that does, or where it goes to. In my case, the SCR was the only module that was bad limiting my ability to get spark at the spark plugs. Once I replaced it, the unit was functioning again. My name is Tom. Thank you.

 

[DavidWang]

Hi Tom, where do you live? I hope you can fix my boat "no spark" issue.

 

[mezzatt]

Hi Tom, where do you live? I hope you can fix my boat "no spark" issue.

I live in Phoenix Arizona

 

[Edson Henriquez]

Hello

I picked up a 1997 Challenger single 787 engine. I am not getting spark on both plugs, changed stator to new OEM one as well as used coil pack pulled from a working machine, no change. Checked ohm values from service manual on: pickup coil (voltages 0.5v), stator, ignition coil pack & cables, all look good.

MPEM beeps twice when I plug the Dess in and engine cranks no problem. I am starting to think it could be MPEM, any way to confirm this? I see the white cable that goes from MPEM to coil pack and it showed me voltages all over the place, how do I test and confirm that its sending signal? Could it be a failed CDI? which is built in to MPEM on these years. Or maybe the pickup coil isn't functioning correctly even though readings look good?

If it is the MPEM, any aftermarket solutions? Would like to get engine running before winter
Any help is appreciated guys!

Interesting … I did the exact tests as you last week and still same problem.. no spark … what did you finally do to get your boat running ?