1996 Challenger Lost Spark... Where to start?

[Waterluvr]

Is the MPEM ground connected to the starter?

It is connected there, along with the main battery ground cable. Looking at the grey panel box it is the black wire coming out of the second watertight seal connector from the top left side that follows the oil lines down to the floor of the bilge and over to the starter.

Check this ground first, and then proceed on to the trigger testing if that doesn't take care of it. I've got a workbench full of carbs that showed up today I need to get finished up and I will get into the color coding for the rpm limiters later tonight.

 

[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.

So I did the best I could checking the trigger coil. I know it's supposed to be around 242... Mine was .59. I am assuming my issue is here.

 

[Waterluvr]

Well, zero would indicate it's shot and a reading of 59 indicates it has some resistance in the circuit. Wonder if it broke the mount back in the housing and that's why it reads so low? Only one way to find out, and that's to get into the mag housing.

What did you find for condition of that MPEM ground cable? If it were me I would want to test everything else and have the results on paper before taking the motor loose to get in that housing. I'm worried about your MPEM after seeing the same path to ground from the battery cooked.

 

[Bmedlin85]

As for as the MPEM ground cable, it is black just like the other was. No broken wires that I can see though. What is the best way to check the cable?

 

[Waterluvr]

Take it loose and ohm it from both ends, visually inspect both ends for any signs of high heat. It looked like someone was welding with the ground lead from the battery and my concern is that the short transferred to the ground side of the MPEM.

Also I'd think better of it if you tested the trigger coil with an adapter before going through all the work to access that housing, a reading of 59 is inconclusive other than it makes me wonder if the coil is ok and maybe it's mount is just broken. It's a job to get in there...

 

[Bmedlin85]

Take it loose and ohm it from both ends, visually inspect both ends for any signs of high heat. It looked like someone was welding with the ground lead from the battery and my concern is that the short transferred to the ground side of the MPEM.

Also I'd think better of it if you tested the trigger coil with an adapter before going through all the work to access that housing, a reading of 59 is inconclusive other than it makes me wonder if the coil is ok and maybe it's mount is just broken. It's a job to get in there...

Good idea. I'm not really wanting to pull that cover. Ok, so what ohm should I look for on the cable? I am getting .62 on the cable.

 

[Bmedlin85]

Here is a pic of the mag plug. Bottom left seems to be burnt.

 

[Waterluvr]

Here is a pic of the mag plug. Bottom left seems to be burnt.
View attachment 26691

Yep, that's fried. Need to reference which wire that is.

Good idea. I'm not really wanting to pull that cover. Ok, so what ohm should I look for on the cable? I am getting .62 on the cable.

Zero is what you should see, a reading of .62 makes me grind my teeth. It really should be zero, or a couple Ohms to indicate resistance from heat or brittle copper or...pick one. We'll say .62 is ok for now. What brand of meter are you using?

On Edit: Curious if your meter is autoranging or selectable for ohm range I assume it's digital. Also, when you touch the test leads together set to any ohm range what sustained reading do you see on it?

 

[Bmedlin85]

Please excuse my crude way of doing this... I tested the black wires going to the plug. They are connected together at the mpem.

 

[Waterluvr]

That's a nice meter you have, suggestion I see you have it set to auto ranging mode try the range setting and see if you can dial that down to clean up those .(00) readings.

 

[Bmedlin85]

Thanks. I will change it tomorrow. Had to clean up for the night, perks of living in an apt and working in the parking lot.

So, that burnt wire. I guess I am going to have to pull the mag cover after all.

 

[Waterluvr]

Thanks. I will change it tomorrow. Had to clean up for the night, perks of living in an apt and working in the parking lot.

So, that burnt wire. I guess I am going to have to pull the mag cover after all.

Yea, that's a sure indication the magic smoke has been let out of something.

 

[Bmedlin85]

So can I assume at this point it's the trigger coil or mag?

 

[Waterluvr]

I really wish you could but we don't have a satisfactory test result for the trigger and that particular pin location of the plug is part of the stator wiring. I think it's reasonable however at this point to get in there and have a look it's all easy to confirm once it's opened up.

 

[Bmedlin85]

I'm going to try to make that adapter so I can get an accurate test reading. So I have an electrical connector kit that I bought from the auto parts store. This kit mainly has connectors the you just crimp onto the wires. Who sells a kit so you can actually do it like from the factory, with the pins in a plug? There are several wiring things I need to fix on this boat and I want to do it the right way and look good. Thanks

 

[Waterluvr]

I'm going to try to make that adapter so I can get an accurate test reading. So I have an electrical connector kit that I bought from the auto parts store. This kit mainly has connectors the you just crimp onto the wires. Who sells a kit so you can actually do it like from the factory, with the pins in a plug? There are several wiring things I need to fix on this boat and I want to do it the right way and look good. Thanks

This is my go to source for most things, they have just about anything made and used in industry and assembly including the white plastic hinges used on Sea-Doo boat cooler and rear engine hatch storage lids, compartment locks and here's a link to their electrical connector selection.

http://www.mcmaster.com/#electrical-plugs-and-receptacles/=sw2xpb

 

[Waterluvr]

On that link, go to their dc voltage plugs and receptacles menu, then scroll down to harsh environment low voltage dc connectors and you'll see a picture of a 4 pole plug they have the 6 pole you need on the menu below it.

You can also buy the connector pins and the tool to crimp and unlock the pics from a connector from them.

The amp rating should be marked on your plug, select replacements accordingly.

 

[Bmedlin85]

Well, I finally got the motor out and the front cover off... This is what I found. Time for a new stator and coil. The hardest part of the whole thing was pulling that dang motor!!! Thanks again for all of your help.

 

[Waterluvr]

Well, I finally got the motor out and the front cover off... This is what I found. Time for a new stator and coil. The hardest part of the whole thing was pulling that dang motor!!! Thanks again for all of your help.
View attachment 26850

Good work! Thanks for updating the thread and taking pictures far to many other people asking for help that can't be bothered to follow up after they get it on here and these troubleshooting threads and pictures are a big help down the line for the next person trying to diagnose their issues.

They really could have left some more elbow room in that engine bay to work huh?

 

[Bmedlin85]

Thanks for following the thread and offering help. Good help is hard to find these days.

Yeah getting that engine out was a beast. It is a shame that you have to pull it just to get into that cover. Well, I guess you do not have to pull it all the way but it sure does make things easier. According to the manual the drive shaft has to be removed in order to remove the engine... Instead of this I just remove the front motor mount. This gave the engine enough room to slide forward off of the shaft. I also had another set of hands helping out so that made it easier as well.

Now just to get some parts together. Thanks for the PM.

 

[Waterluvr]

Your welcome, always happy to lend some knowledge when I can. So with any luck no one else is interested in those parts that's one heck of a good deal if it plays out for that price.

Suggestion, since you're that far into it already I'd sure think about installing a new shaft drive for the oil pump or at least have a good look at what's there for wear and tear.

 

[Upallnight]

I used a gantry crane that I built for about 40 bucks from 2x4 and 2x6 to lift out the engine and reinstall the engine for my Sportster. An electric winch attach at the top of the gantry crane did the heavy lifting.

 

[Bmedlin85]

Very nice setup Upallnight. If I was going to be pulling the motor often this would be a great way to spend $40.00 haha.

Waterluvr, I have a question about the rotary valve cover. I removed this cover yesterday and it has some pretty bad pitting in the cover itself. The rotary valve seems to be okay and there is very little damage to the case side. Should replace this cover? Also, if I replace the cover is it necessary to replace the replace the valve as well?

The deeper I get into this thing the more stuff I find, driving me crazy since I paid the price of a running boat SMH.

 

[Waterluvr]

Just the exterior of the cover huh? I like to poke around those areas with an awl or pick and see just how bad that pitting is, a little destructive testing is prudent for areas that look like galvanic corrosion is the culprit.

I usually clean a painted part like that in the blast cabinet so you can see the metal alloy, you don't want an air leak through that cover screwing up your fuel/air delivery.

Those covers are cheap used so it's your call if it can be cleaned and painted or buy another one, don't take a chance if the corrosion is so bad it might leak air that's going to murder the engine on the back side of the carbs.

 

[Bmedlin85]

Just the exterior of the cover huh? I like to poke around those areas with an awl or pick and see just how bad that pitting is, a little destructive testing is prudent for areas that look like galvanic corrosion is the culprit.

I usually clean a painted part like that in the blast cabinet so you can see the metal alloy, you don't want an air leak through that cover screwing up your fuel/air delivery.

Those covers are cheap used so it's your call if it can be cleaned and painted or buy another one, don't take a chance if the corrosion is so bad it might leak air that's going to murder the engine on the back side of the carbs.

The exterior of the cover does have alot of corrosion on it but the pitting is actually on the side of the cover with the rotary valve. I will take a picture this evening.