Help No Spark Neither engine 1999 Challenger 1800

[WHYMpem]

I have owned this boat for 4 days and I have had nothing but issues. Let me give you the run down on what's going on.
Thursday
Bought the boat from a guy that could not get it started. He would push the start buttons and nothing. So I jumped the starting soloinoids with screw driver. After the engines fired up the buttons started to work again. So I checked the compression had 150 in one engine 130 in the other Knowing I'm going to have to rebuild the top end on the one that tested out at 130 I offered him 2700 he agreeded so I bought boat and was on my way.
Friday
Put the boat in water Fired the boat up and noticed that smoke was going everywhere. Called the guy I bought it from. Come to find out he mixed it 50:1 and had oil in the oil tank. So it was running super rich. When I applied gas the boat took off after a slow start up. I noticed the rpms was not matching I figured it was because the engine compression being as low as it is. Then out of the blue the motor on the port side shutoff and could not get it back on. I made it back to the dock on one engine. I thought the spark plugs where shot because of how rich the boat was running. So I replaced them. I also got a charger and charged battery. Finally got both engines working again. So I took it out on test ride for about 30 min it ran fine. Then it dropped and could not go over 15 mph. So I turned it off and when I tried to turn back on it would not start. Had dad tow me in on his boat. Once I got back to shore I pulled plugs and had no spark in either engine. Went to store and replaced battery still nothing. I tried putting test light on white wire of coil while dad tried starting it and no light. I'm lost.

Notes that might help
I have no beep when dess key is inserted
The starboard engine is missing temp sensor.
I hope it's not mpem

 

[Hemidakota93]

Voltage on f2 and f3? In the upper fuse block on the mpem. Also are you getting voltage to the nav lights and bilge pump?

 

[WHYMpem]

Yah every one is good but F2 and F3

 

[Hemidakota93]

Same problem I had. It was the mpem. Good news though! I know where a good working used one is with a key.

 

[WHYMpem]

Same problem I had. It was the mpem. Good news though! I know where a good working used one is with a key.

Where would that be located at?

 

[Hemidakota93]

Westside powersports. Talk to Jess.

 

[WHYMpem]

Yah I might have to give them a call. I just bought a Mpem for 150 of eBay. The guy said it came out a 99 challenger that lost spark in one engine. He got water in the other engine so he just parted everything out. So I figured for 150$ I'd take a chance.

 

[Hemidakota93]

I haven't messed with troubleshooting one engine dead. As far as I know the mpem is sealed. Making working on it difficult.

 

[WHYMpem]

Well wouldn't you think it would be more likely a sator coil or starter problem if it's just one engine?

 

[Hemidakota93]

No. If the rpm circuit went bad in an mpem (happens a lot) then only one engine will run. You can try it though.

 

[WHYMpem]

No. If the rpm circuit went bad in an mpem (happens a lot) then only one engine will run. You can try it though.

Hey when testing the f2 and f3 do I need to try turning engine over or should it have 12 volts regardless? Also what you mean by rpm circuit?

 

[Hemidakota93]

F2 and f3 will show 12v when the lanyard is attached. If you're showing less then you have a bad mpem. The rev limiters and spark controllers are in the rpm circuit. It's basically a translator/limiter to get the signal from the pickup coil to the ignition coil.

 

[WHYMpem]

F2 and f3 will show 12v when the lanyard is attached. If you're showing less then you have a bad mpem. The rev limiters and spark controllers are in the rpm circuit. It's basically a translator/limiter to get the signal from the pickup coil to the ignition coil.

Any way you can test board with out key?

 

[Hemidakota93]

Nope. The key triggers the internal relay that powers those two circuits. You can try to apply 12v to those fuses from the battery and see if it starts. If it does than it most definitely your mpem.

 

[mobilefleet]

if your engine spins over but wont start, look at the rpm gauge while cranking. if it moves there's nothing wrong with the pickup coil in the stator housing. Check your engine ground cable running from the electrical box where the mpem is housed to the bottom of the starter on the engine that wont start. When just one engine wont run it's a good possibility the cable needs replaced even if it looks good, they corrode over time from inside out and cannot be seen. Get a 4 gauge cable of sufficient length from the auto parts store

 

[Hemidakota93]

Again, this is for sure an mpem issue with the symptoms that have been described. Ask me how I know?

 

[WHYMpem]

if your engine spins over but wont start, look at the rpm gauge while cranking. if it moves there's nothing wrong with the pickup coil in the stator housing. Check your engine ground cable running from the electrical box where the mpem is housed to the bottom of the starter on the engine that wont start. When just one engine wont run it's a good possibility the cable needs replaced even if it looks good, they corrode over time from inside out and cannot be seen. Get a 4 gauge cable of sufficient length from the auto parts store

Yah I'm takeing a chance on a mpem that came out of a boat that lost spark in one engine. My mpem is toast I have no spark in both engines. So I'm takeing a chance on this other board because the guy only wanted 150$ Sucks I have to get dess key to go with it just to find out if it works, but that's part of the gamble.

 

[Didehcho]

Haha how do you know. My challenger just lost spark single engine

 

[Hemidakota93]

Haha how do you know. My challenger just lost spark single engine

You need to go through all the testing to rule out an engine component failure before you jump into mpem diagnostics. Dual engine spark failure is more likely an mpem failure. The reason I know is because I myself went through that issue. It's highly unlikely that a component in the spark circuit went bad on both engines at the same time.