DESS or MPEM problem Seadoo Challenger 1800 1998

[CadeZ]

So my dad and I recently got ourselves a new project. A 1998 Seadoo Challenger 1800 with twin 787 engines. The oil pump is currently blocked off. Other than that, there is no other motifications to the boat.
We got it home and got both engines running fairly smoothly. Perfect! Now, our problem. A couple days after, we put the lanyard on and we got a constant beeping noise. Went through a couple diagnoses and figure out our engine temp sensor was going bad. After taking off the wire, we put the layard back on now we got two long beeps and when we try and start the engines there is a constant beep every second or so, never stops and one engine will turn over and the other won’t. On the engine that wouldn’t turn over, I heard a clicking noise in the solenoid. I went deeper into the advanced diagnoses in the manual and got 2 short beeps which stands for problems with the lanyard, DESS or MPEM. My first test- I unplugged the 3 wire harness connected to the DESS post. Tests the black/yellow to black wire and was 0 ohms.

Not sure what to do now. Any help is very very appreciated. I am stuck and there are not many dealers or mechanics around my area that will work on these boats. Thanks for any info.

 

[racerxxx]

Ok, advanced diag. Press start button 5 times without lanyard on. Will beep to tell you you're in. Install lanyard and try and start engine---either one. If it turns over it knows your key. Rock and roll.

I'm thinking constant beeping, low fuel. Press the fuel rocker switch and the beeping should stop. By acknowledging the beep by pressing the rocker switch you're now warned that you're "on reserve" and to get back to dock. There technically in no reserve on these boats since there is no manual fuel valve. It's a constant beep warning until you acknowledge.

Other engine, tap on solenoid or try and bridge it with pliers to start engine. replace as necessary.

Somewhere on here Me or someone else has listed the advanced diag beep sequence. It's also in the manual for the jet boats. I'll see if I can find it.

 

[racerxxx]

Just a quick google netted me this one, I wasn't digging deeper to find the one i did....it's all the same jargon anyway. Also clean the inside of the cap and the out side of the post and the center button on the dess post. I use fine steel wool and then wash it off really good and dry it.

Here is all the info on the DESS codes. It is possible that you are getting a mixed code.
DESS Codes/ Beeps
2 Short beeps …the engine is ready to start
1 Long beep …no communication to MPEM
4 Short beeps… (on Jet Boats) Shifter is in gear
8 Short beeps…defective MPEM
1 Continual beep…engine over heating


Advanced Self- Diagnostic Mode


By pushing the start/stop button 5 times, you’re putting the DESS in advanced diagnostics. When you have successfully done this, you'll hear 1 short, 1 long beep then, put on the lanyard cap. The engines should start if everything is ok.

2 Short beeps means MPEM can’t read the lanyard cap or it has bad magnet. It could be a bad wire connection at the Lanyard switch.
2 Long beeps means wrong lanyard or bad connection of DESS connection
3 beeps signal the wiring harness of the DESS switch are grounded, or a short circuit somewhere.

You may have a bad connection in your wiring harness, from corrosion. Go through your electrical systems connectors and check for corrosion. Clean them with some contact cleaner, then die-electric grease.

To listen to the codes again start from the beginning.



Original thread for the codes
97 Challenger 1800 Beep Codes????

 

[CadeZ]

Okay. Thank you for the input. I tried the advanced diagnostic and it was 2 short beeps, I unplugged the wiring harness to the DESS lanyard plug in and tested the wires out at 0 ohms. Looks good there.
I saw another post as well that said a constant beep every second or so was low fuel. But I just put 10 gallons of premix in 2 days ago.

It got late tonight, I will try to bypass the solenoids tomorrow.

Thanks for your help.

 

[snikwad003]

. There technically in no reserve on these boats since there is no manual fuel valve. It's a constant beep warning until you acknowledge.

No true reserve, but the fuel switches are under the hatch on the drivers side, the reserve port is capped off. Unless they ditched them in 98.

 

[racerxxx]

No true reserve, but the fuel switches are under the hatch on the drivers side, the reserve port is capped off. Unless they ditched them in 98.

The bigger 1800 and Speedster in 98+ do not have fuel selectors, it's just an audible alarm that you acknowledge by the rocker switch.



1998 Challenger 1800 fuel system

1998 Challenger Fuel system Item #15

 

[CadeZ]

Okay so after another days work- the symptoms stayed the same.

First we by passed the solenoid that was making the clicking noise, allowing for the engine to turn over. Great! So we need a new solenoid.

Next we pulled the plugs and realized we were not getting spark to either plug. Still not sure why.



The other problem we had was with the lanyard and DESS post. So the symptoms are very random. Sometimes we get the 2 short beeps meaning everything is ready to go, everything works then. But sometimes we get either no beep at all or just 1 long beep. We cleaned out the lanyard and post with contact cleaner and put dialectic grease on them. Same symptoms. I don’t know if this means bad lanyard or what? We’re confused how it works and sometimes it won’t.



Should we order an oem solenoid or does it really matter if it’s aftermarket?



Thanks again for all your help.

 

[CadeZ]

We fixed the spark issue. Our battery voltage was dropping below 10 volts when trying to start. So we hooked up some cables and tried to start.
Driver side engine starts up and runs great, as usual. Passenger side will turn over but will not start. Very weird because it has always ran until we ran into these problems.

Thanks for your help.

 

[CadeZ]

Okay. More info, our spark issue seems to be intermittent. It will work sometimes, and other times it won’t.
Our issue with the DESS post and lanyard is somewhat fixed, works about 70% or the time.

Now, a new problem has occurred. As we were taking the plugs out, we noticed what looks like some oil in the cylinder towards the back of the boat. But not in the other cylinder. There’s not a lot of oil, motor still turns freely and doesn’t sound bad. Afraid of what this could mean. Any help is appreciated. Thanks

 

[racerxxx]

That oil is probably a leaking inner crank seal, which isn't good news. But, I'd push forward and see if you can get it running. You'll want to crank it to get that oil out. Put a rag over the head as crank it over with the plugs out. It can get messy

 

[CadeZ]

Okay will do. Why would it only be leaking into one cylinder and not the other?
Also any suggestions on the spark issue?
Thanks!

 

[racerxxx]

The crankcase is divided and the rotary gear is in the middle. So.....maybe the one seal is seeping oil.

Well, I would make darn sure the battery is good, get it load tested. I know the battery is on the port (left) side of the boat, I just don't remember if it goes to the port engine first or the starboard first or splits right at the battery switch...... There is a short ground wire (battery cable size) that links the 2 engines together, from the front of one magneto housing to the other.. If that is loose or corroded it might not have a good ground. I think it grounds thru the starboard engine----key word is think. The rear ebox that houses the solenoid and coil, check continuity from the grounds on the coil mounting screw out to the engine and to the battery. If the magneto doesn't have a ground you can crank it all day long and not get spark. There are test procedures in the shop manual for testing the DESS post, the magneto, the coil and the magneto pick up. You can google for teh manual and if you can't find a boat manual see if you can download a 96-99 XP or SPX manual

 

[CadeZ]

The new solenoid came in the mail today. Replaced the old one and both engines roared up the life, consistently starting and getting spark.

We decided to take it out on the lake today to test drive it. The boat started right up and ran farely well with the exception of some carb issues which we knew we had. The engine with the oil in one cylinder smoked a little more than normal on start up but once it got warmed up it ran good with no smoke at all.

The one problem we found was that we were hardly getting the lanyard to work at all. It gave us 2 ready to go beeps maybe twice during the whole day. Most of the time it would make no noise but would start up anyways. Other times it would make no noise but when I tried to start the engine it just beeped at me. Not sure if this could mean bad speaker/beeper? I’m not sure.

 

[CadeZ]

Throughout our time of having this boat I have also noticed a small amount of 2 stroke oil leaking into the bilge after sitting for a while. I have consistently been cleaning it up. I’ve read things on hoses being old, clamps being broken and the gasket on the oil reservoir being bad. I haven’t found any of those to be the problem. I can’t get to one hose that goes under the engine though. The oil seems to be coming from under the passenger side engine.

Any help, thanks!

 

[mikidymac]

The hose clamps can cut the hose going to the rotary gear cavity just like you are describing.
Also the small 3/32" oil lines from the pump to the intake get old an hard and break seizing the engine so I always recommend changing them.

You also say you have carb issues so it is a good time to rebuild them before you run lean and seize an engine.

 

[CadeZ]

Okay. I’ll check the hose clamps. But we have the oil injection blocked off. We are mixing the gas.
Second, the problem we are having is a bog around 2000 to 3500 rpms as well as a bog when accelerating farely quickly. We are going to rebuild the carbs pretty soon. Just wondering if this is really a symptom of running lean?

 

[racerxxx]

Stop running the boat, Pretty soon is not soon enough. 2 strokes require a clean fuel system. I know you are anxious but you really need to refrain and just rebuild the carbs. You will kill it if you think the fuel is going to "clean" the carbs out from running. @mikidymac has a thread on how to rebuild the carbs. Rebuild kits run from $40 to $46 per kit shipped, you need 4. Do not use the arms or springs in the kits. You'll also need new needle and seats. The should be 1.5's Carb kit part # is
MK-BN38/44 SPR. ONLY GENUINE MIKUNI PARTS

 

[mikidymac]

And in addition to what racer said you still have oil lines feeding the rotary gear even with premix and you better have oil in the tank to feed it. These are the lines typically cut by the hose clamps and leaking into the bilge.

 

[CadeZ]

Okay. Looks like I will be rebuilding the carbs this weekend then. But yes, I know the oil reservoir is still feeding the rotary valve. I have filled the reservoir up with oil and is good. I will look into the lines being ripped. Thanks!
I work on other two strokes quite often and it seems like these engine are more prone to blowing up with carbs out of adjustment? None of the other two stroke engines I have messed would blow up because the carbs are out of adjustment unless you run it for quite a long time.

Thanks for your help.

 

[CadeZ]

My other question would be. The previous owner rebuilt the carbs but with aftermarket kits. Do you think I could just got through them and clean the carb or no? I’m not afraid to buy the oem but if there’s no need to.

Thanks!

 

[mikidymac]

Any 2-stroke running lean will blow up just like the other PWC’s. It’s typically one carb that is really bad so it runs on the other cylinder till the lean one seizes. It’s not that they are “out of adjustment”, it that they are plugged or inferior parts have been installed that restricts correct fueling.

If you have any indication they are aftermarket carb kits that’s probably your problem. Replace with only genuine Mikuni kits.