1996 Challenger Lost Spark... Where to start?

[Bmedlin85]

Okay,

So I purchased a running 96 Challenger a few weeks ago. Last week I took it out on the 3rd, 4th, and 5th for at least 3 hours each day. During this time I had no issues. This past Monday I made it out 30 minutes and all of a sudden it just dies, no bogging or anything. Its like the lanyard was pulled. I got a chance to look at it yesterday and it appears that I have no spark on either plug. I have worked on Seadoo's before but not to much with the electrical. Can anyone tell me where I should start? The engine does turn over and I get 2 beeps when I plug the lanyard in. Any help would be much appreciated.

Thanks in advance.

 

[Waterluvr]

If you're certain both coils and wires aren't firing the plugs open the box and inspect the 15 amp fuse for the charging system. If voltage is to low the MPEM board won't fire the coils. Battery condition matters to the extent it's fully charged and spinning the starter motor up without being lethargic. If the fuse is blown your not getting charge voltage back to the board from the stator when the motor cranks and the MPEM is sensing low voltage.

If in doubt about the battery condition, disconnect it from the boat's + & - cables and charge it and have it load tested if it's acting up.

On Edit: It might be worth a shot to isolate the rectifier after checking the battery and charging system fuse, I'm not certain if a failed rectifier can totally shut the ignition down if the system is being run on a fully charged battery or not but there should be four wires with bullet connectors on the rectifier, three yellow and one red. Unplug the red wire and shield that open connector while you crank the engine to test for spark.

 

[Bmedlin85]

If you're certain both coils and wires aren't firing the plugs open the box and inspect the 15 amp fuse for the charging system. If voltage is to low the MPEM board won't fire the coils. Battery condition matters to the extent it's fully charged and spinning the starter motor up without being lethargic. If the fuse is blown your not getting charge voltage back to the board from the stator when the motor cranks and the MPEM is sensing low voltage.

If in doubt about the battery condition, disconnect it from the boat's + & - cables and charge it and have it load tested if it's acting up.

Thank you for the quick reply Waterluvr.

The charging system fuse is good. I checked all of the fuses in the MPEM box and inside the storage compartment. All of the fuses checked out.

The battery is also good.

I will have to have to check the rectifier for spark...

Thanks again

 

[Waterluvr]

I hope a bad rectifier can cause that, it's a cheap and easy fix.

 

[Bmedlin85]

I hope a bad rectifier can cause that, it's a cheap and easy fix.

Is the rectifier mounted in the MPEM box?

 

[Waterluvr]

Yep, it's easy to check just unplug the red wire's at the bullet connector and see if you have fire.

 

[Bmedlin85]

Yep, it's easy to check just unplug the red wire's at the bullet connector and see if you have fire.

Ok, sorry I have not replied back to this. I didn't really have time to work on it this past weekend. So if I unplug the red wires should I get spark at the plugs if the rectifier is bad? I guess I am a bit confused. I've never been big with electronics.

Thanks again

 

[Waterluvr]

Ok, sorry I have not replied back to this. I didn't really have time to work on it this past weekend. So if I unplug the red wires should I get spark at the plugs if the rectifier is bad? I guess I am a bit confused. I've never been big with electronics.

Thanks again

So essentially every electrical function in the boat is controlled by the MPEM board unless it's something switched for operator control such as running lights, the blower etc. same as any automobile ECM, ECU module that runs the engine, transmission and associated functions.

One of those function's of the MPEM is the origination of the ignition pulse signal for the coils, also timing that can influence rpm's etc. Those boards have some built in thresholds for low voltage that are known to affect the ignition side of things and one of the known quick fixes/tests is to simply unplug the red wire on the rectifier to prevent it from sending a low voltage signal back to the MPEM in the event it has failed. For owners having the issue of not being able to achieve full throttle operation a failed rectifier is known to limit operation to roughly 3-4000 rpm's and unplugging that red wire clears it right up providing the battery is fully charged and capable of sustaining a load on it.

Whatever the battery has for voltage at that stage is what the board is going to sense and respond accordingly if it thinks all is well again assuming you have a battery that is reasonably close to having a full charge, if it's been pulled down not likely you will see a change.

Battery condition is a big deal with the electronics in these boats, if in doubt don't hesitate to pull the battery and have it load tested. Also, you can simply test the battery voltage with the boat running and the rectifier plugged in to see if your getting a regulated charge back to the battery, that's the rectifiers function in your charging system loop.

The rectifier test of unplugging the red wire is just another one of the known things to try for those of us that don't have the ability to plug in diagnostics as you would see at a dealer shop. Make sure your battery is 100% good to go, unplug the rectifier red wire at the bullet connector and wait five minutes to make sure the MPEM resets and you get the 2 loud beeps from the DESS when you plug it in on the dash post.

Make sure you have the correct spark plugs in your boat, and if you know anyone that has a marine ignition tester like the one I use you could borrow it makes verifying spark or the lack of it much easier as it clearly shows the secondary ignition pulse on each plug wire across the resistance board.

 

[Bmedlin85]

Excellent information Waterluvr!!!

So again, if the rectifier is the issue, with the red wire disconnected and a fresh battery, the boat should start... I will try this tonight. I really appreciate all of the information and help. I have only had the thing for a few weeks and have not gotten to use it to much.

Also, this cable is what was connected from the starter to the negative post on the battery. Could this be an issue as well?

 

[Waterluvr]

Excellent information Waterluvr!!!

So again, if the rectifier is the issue, with the red wire disconnected and a fresh battery, the boat should start... I will try this tonight. I really appreciate all of the information and help. I have only had the thing for a few weeks and have not gotten to use it to much.

Also, this cable is what was connected from the starter to the negative post on the battery. Could this be an issue as well?
View attachment 26567

You bet it is, that needs all new cable and properly crimped termination rings that whole mess is nothing but a hot spot and resistance to an already very picky electronic control system.

 

[Bmedlin85]

That is what I was thinking... You can tell this was a homemade job SMH. I purchased a new negative cable from the parts store that I am going to install tonight. Maybe with all things together I can get some sort of action.

I have another question for you, the previous owner installed an electronic fuel pump and removed the fuel pump components from the mag carb. I am thinking I need to remove this setup all together and go back to stock. Any thoughs? The picture shows a plate installed in the place of the stock pump. Some people should not be allowed to work on things.

 

[Waterluvr]

I agree with you on removing that 12VDC pump, the SBN series carbs were not designed to work with one. In fact, I'd go ahead and pull them down and kit them right away and be sure to get a new accelerator pump diaphragm as well. The accelerator pump nozzles are notorious for stopping up on these carbs, make sure they flow carb cleaner under pressure from the straw on the inlet side of both of them and use new seats and viton tipped needles as well.

 

[Bmedlin85]

Glad to be on the same page. Now to just find the parts I need OR a whole new mag carb all together. He also remove the choke from that carb... Its a shame I didn't realize how bad the boat was hacked before I bought it. Guess it happens though, owell. I am going to try for the spark this evening and go from there. If I am not getting spark the fuel is not really an issue haha.

Once I get these issues resolved I will get into my cavitation issue.

Thanks again for the help.

 

[Bmedlin85]

Well I disconnected the red wire coming from the rectifier and installed a fresh battery... Still no spark.

 

[Waterluvr]

Well I disconnected the red wire coming from the rectifier and installed a fresh battery... Still no spark.

Ok, time to get the multi-meter out and get into the manual for testing procedures. Let's see if there are any issues with the mag side of things, do you have the shop manual for your boat and do you have a multi-meter and know how to use one and check ohms etc?

 

[Bmedlin85]

Yes I do have the manual (I got from here) and yes I do have a multimeter. Still learning how to use it but I can check the ohms.

 

[Waterluvr]

Yes I do have the manual (I got from here) and yes I do have a multimeter. Still learning how to use it but I can check the ohms.

Ok, pretty sure my '97 Challenger manual is the same as the '96 when I get time tonight I will get into that and read up on the Magneto section and how it charges the coils and would encourage you to do the same, I have some initial concerns for the Mag and that toasted ground wire, need to see how that might impede coil operation and get some tests done.

On Edit: Your going to want to start at the top of Section 7 / Subsection 02 of the manual and read the entire subsection that transitions to 03 and then changes to spark plugs.

 

[Bmedlin85]

Ok, pretty sure my '97 Challenger manual is the same as the '96 when I get time tonight I will get into that and read up on the Magneto section and would encourage you to do the same, I have some initial concerns for the Mag and that toasted ground wire, need to see how that might impede the MPEM operation and get some tests done.

I haven't been into that area on one yet so this is new to me as well but I bet we find something has gone wrong there.

I have looked through it some but do not have the adapter it calls for for testing the stator or magneto. I am basically learning this electrical system as I go.

I installed the new ground wire and that didn't seem to do anything.

I do really appreciate your help.

 

[Waterluvr]

I have looked through it some but do not have the adapter it calls for for testing the stator or magneto. I am basically learning this electrical system as I go.

I installed the new ground wire and that didn't seem to do anything.

I do really appreciate your help.

That's ok, you can still probe the two pins on the trigger coil for starters I just went through the manual and subsequently performed the same tests on my system. For instance, when I probed my trigger coil I get 256 Ohms through it and that's pretty close to the manual's number of 242.

 

[Bmedlin85]

I found what you are talking about. Which pins would I connect to since I do not have the adapter?
View attachment Trigger Coil.pdf

 

[Waterluvr]

I found what you are talking about. Which pins would I connect to since I do not have the adapter?
View attachment 26609

Probe the top and middle pins in the mag connector on the right side of the stationary plug-in as if looking at the boat from the swim platform for proper orientation. If you don't mind spending a few bucks to make life easier Radio Shack will have the pins used in that connector just solder them on the ends of two test wires and crimp alligator clamps to the other end to make attaching to the meter probes easier on you. Worth the time to make your own harness, those are female connector pins btw used on the test harness.

If this doesn't pass the test you're going to have to get into the Mag cover which is a bit of job, but from there it's pretty easy to find what's gone wrong and we can get into those specifics when the cover is off.

I really suspect there's trouble in there after seeing your toasty ground lead, also check the black ground wire on the MPEM like right away to, if that's been compromised it will cause grief.

 

[Bmedlin85]

Probe the top and middle pins in the mag connector on the right side of the stationary plug-in as if looking at the boat from the swim platform for proper orientation. If you don't mind spending a few bucks to make life easier Radio Shack will have the pins used in that connector just solder them on the ends of two test wires and crimp alligator clamps to the other end to make attaching to the meter probes easier on you. Worth the time to make your own harness, those are female connector pins btw used on the test harness.

If this doesn't pass the test you're going to have to get into the Mag cover which is a bit of job, but from there it's pretty easy to find what's gone wrong and we can get into those specifics when the cover is off.

I really suspect there's trouble in there after seeing your toasty ground lead, also check the black ground wire on the MPEM like right away to, if that's been compromised it will cause grief.

Well I tried this without a connector and I just cant get to the pins, so I will have to make one as you recommended. Now according to the manual I should have 6 wires connecting to the mag... a YE/WH/GN, BK, BK, YE/GN, YE/GN, and YE/GN. Mine has a YE/WH instead of the YE/WH/GN. Here is now mine is set up:
BK - YE/GN
YE/WH - YE/GN
BK - YE/GN
This would be if you were looking at the plug from the front of the engine.

While I am getting a connector together I attempted to troubleshoot the MPEM as stated in the manual but am having issues here as well. The manual states to disconnect the Black/Green/Red wire from the magneto system and if the problem is solved then the MPEM is bad. I cannot find such a wire throughout the whole boat. I do know the owner before me rewired a lot of things so now I am having the issue of tracing wires.

 

[Waterluvr]

From the perspective of looking at the front of the motor from the mag side it's still the top and middle pins, left side of the connector. I believe the portion of that MPEM test you referred to when trying to locate the wires is for the purpose of testing the RPM limiters, I'm not near the boat (or my benchtop PC with the manual) right now but when I get back I'll trace those color codes and see what they are.

If you're working on it right now, be sure and check the MPEM ground first as you had that other smoked cable I'd almost bet you have an issue there as well. 98% of all wiring issues I ever got into the fault was found at a ground connection or in the related circuit.

 

[Waterluvr]

Ok, back home and have the right reference material now. So I went back to your earlier post to see if it was the main battery or MPEM cable that self-immolated and saw it was the battery. Unhook the cables from the battery and take that back loose at the starter and remove the MPEM ground cable and don't be afraid to strip off the casing to see if it's cooked for last few inches or worse.

Also if you're using a meter with short probes and leads, you could just use sewing needles and some gator clips to hold the probes into the backside of the connector to check the trigger function ohms.

I'll work on deciphering the rpm limiter wire colors.

 

[Bmedlin85]

Ok, back home and have the right reference material now. So I went back to your earlier post to see if it was the main battery or MPEM cable that self-immolated and saw it was the battery. Unhook the cables from the battery and take that back loose at the starter and remove the MPEM ground cable and don't be afraid to strip off the casing to see if it's cooked for last few inches or worse.

Also if you're using a meter with short probes and leads, you could just use sewing needles and some gator clips to hold the probes into the backside of the connector to check the trigger function ohms.

I'll work on deciphering the rpm limiter wire colors.

Is the MPEM ground connected to the starter?