Proud (maybe sad) new owner--1997 GTX...Bad MPEM?

[paulw]

I'm new to this whole PWC thing, but I "inherited" a '97 GTX in non-running condition. It's been sitting for a couple of years, but fuel system was treated, and so far everything looks pretty good. I'm a competent mechanic, but this is my first PWC, so I don't have a lot of experience with them. However...I DL'ed all the manuals (service, parts, owners) and I've been pecking around the internet for the last few days looking into this problem. Previous owner had concluded that the MPEM was bad (I think his repair shop told him this). When I plug the DESS cap (key) on, I get no beeps, but the "info center" gauge does light up, along with an overheating indicator. No crank, no start. I noticed that the area for the oil and fuel gauges doesn't light up along with the rest of the LCD's when button is pushed, but that might be normal, I dunno. The red LED indicator lights up also, and the clock/compass/temp indicators seem to be working. I've tried the "advanced diagnostics" as per the manual, pressing the start button five times, then plugging in the key. I do get the short/long beep as indicated, but that's all... nothing after that, except that same overheating indicator. Here's what I've done so far:
I tested the beeper, and found it wasn't working. I removed it, and with a few taps to shake things loose, and a little "slickem" in there, it started working again just fine. I have tested the engine temp sensor, it's good(no continuity when cold, good continuity when hot) I've checked the temp sensor wires to the MPEM, and that circuit is good. Start switch seems good, as it lights up the display. Fuses in rear electrical box, and in front electrical box are good, and I have 12 volts to the MPEM. Poking around on the web, I see that it seems like the key and post are a common problem, but because I get some beeps and lights, I think these are okay. Other than some continuity test, I don't really see any way to test them, though. According to the continuity tests they are good. I've unplugged and re-seated all the wire connectors to the MPEM, checking for corrosion/bad connections..Nothing obvious there, either. They all look good. So now I'm down to the MPEM. Looking around on the web again, I see these things have some shocking prices (not too surprising-probably the reason I got the thing for free). Before I lay out that kinda dough, I'd like to ask the group if there's anything I might have missed. Are there any other obvious causes for the weird overheating indicator and the lack of beeps?
I see several used MPEM's for sale, and also some pretty cheap aftermarket replacements(no more coded keys with those, either!), but I can't find anyone who has firsthand experience with the cheaper aftermarket units. Anyone have an opinion about new vs. used vs. aftermarket? Since I got the machine for nothing, and the rest of it looks pretty good, it's probably worth spending a few bucks to fix....THoughts?

 

[LouDoo]

Ht and welcome to the SeaDoo forum.

We have a member, Nick [MENTION=41828]Minnetonka4me[/MENTION] who is the official/unofficial used parts supplier for the forum. If you send your MPEM to him he can test it for you, if it's O.K. there's a nominal charge, if its bad he can sell you a good used one at a good price and apply the testing charge toward the replacement.

Lou

 

[Krispy]

Ht and welcome to the SeaDoo forum.

We have a member, Nick [MENTION=41828]Minnetonka4me[/MENTION] who is the official/unofficial used parts supplier for the forum. If you send your MPEM to him he can test it for you, if it's O.K. there's a nominal charge, if its bad he can sell you a good used one at a good price and apply the testing charge toward the replacement.

Lou

+1 for [MENTION=41828]Minnetonka4me[/MENTION] I purchased my MPEM from him and it came with a new programmed key. Buying from him gave me an added bonus, if it turned out that the MPEM was not my problem he was willing to accept a return if I paid shipping (Minus a 20$ fee for using his MPEM as a testing tool). His price was similar to what I found elsewhere but his service with the MPEM issue was top notch.

As to your original post, have a look at my MPEM troubleshooting thread. I ended up needing a new MPEM as well.

But lets not assume doom and gloom at this point. Lets start checking some of the basic stuff first.

You have determined that your beeper is working (after "resetting the force transducer"-aka smacking it on something) But you still get a no crank no start.

Lets check a few things.

1. Can you turn the engine over by hand? By grabbing the driveshaft/ PTO at the rear of the engine (pull the spark plugs out to make this easier)
2. Have you tried shorting the solenoid in the rear e-box to see if you can get the engine to turn over under starter power?

-->Assuming the answer to #1 and #2 is yes, the next step would be to see if you are getting a signal at the starter solenoid when you push the start button.

If this is yes, the engine should be turning over, then we can check for spark and fuel and ultimately be running.

If not, then we are back to troubleshooting a MPEM. The crappy thing about the 97 MPEM (at least on a GSX) is that the CDI box is integrated into the MPEM, this means that when the CDI fails, the computer goes with it. On my other ski (96XP) the units are able to be replaced separately.

Check the basic tests I posted above and let me know what you find out. We will go from there!

Goodluck!

-Chris

 

[Krispy]

*double post

 

[Minnetonka4me]

If the gauge lights up when you put the key on the MPEM, it should be ok. Here is what to test.

#1 hook the beeper back up and see if you get two beeps when key is put on.

#2 if that works, then go into the rear ebox and jump the solenoid. If it turns over, then unhook the connector going into the solenoid and check for 12 volts when the key is on and you hit the start button. If you get 12volts, you just need an solenoid.

#3 if you dont get 12volts there, then check the wiring back to the MPEM.

If theres nothing, theres something wrong with that circuit on the MPEM. That isnt a frequent failure though so def worth going through the starter circuit.

If the beeper isnt making a constant noise with the overheat light on means more than likely the LCD is on its way out. You could try to unhook the tan wire running up to the LCD but Im guessing the light will stay on. I would just ignore it until the gauge dies completely.

 

[paulw]

Thanx for the reply! I get no beeps when plugging the key on, but the display lights up in "self check" mode. Compass, clock, etc. seem to be functioning as they should. Timer seems okay, it turns off after a bit. I didn't time it, but it seems shorter than the 33 seconds the book mentions. In "advanced diagnostic" pushing the start button five times, then connecting the key, etc. I do get the short/long beep as the book says, but nothing after that. No beep, but the display shows "hi-temp" for the engine. The wire to the temp switch on the engine was cut, I think the previous owner was trying to override this. I tested the temp switch both cold, and after putting it in hot water. It works as it should. If I ground the engine temp switch wire to the block, I get the red light and a constant tone from the beeper. Connected to the temp switch, I get no beep, but just the "hi-temp" on the gauge. I believe that circuit is working as it should. Engine turns over okay. I can jump the start relay in the rear electrical box and it'll crank, but not start. (I turned it by hand also while looking at the impeller-figured if the impeller was bad, it wasn't worth fixing.) I have not checked for 12 volts to the start relay from the MPEM, but the rest of the circuit is good, so if it was getting voltage for the MPEM, it'd crank, right? I've checked grounds, and MPEM connections..They all looked good, and I've verified that I have 12 volts to the MPEM, and that all fuses are okay. Unless there's something really wierd, I'm back to the MPEM, or maybe the key and/or post, but they seem to test okay....? The manual kinda goes around the MPEM, but it gives lots of info aout testing sensors, switches, etc..I think I've checked everything, but being not too familiar with these "Sea-Doo things", I always wonder if there's something I missed...

I have contacted Nick@minnetonka4me via PM, and with the extra kudos to him from other board members (thanx for that!), I think we'll be doing business soon.

 

[Minnetonka4me]

You need to just replace the DESS post most likely. It could be the key, but usually its the post.

I thought I had read the gauges were coming on when the key went on the post....that was why I posted what I did above.

 

[paulw]

Is it possible that the DESS post can test good with ohmmeter, but still be bad? (I haven't actually done this yet, but I can after work tonite.)

 

[Minnetonka4me]

I dont know the answer off hand I just plug in a replacement and try it....lol

 

[paulw]

FESS post tests good. Even if the DESS post WAS bad, it still wouldn't explain the persistent overheating indicator.... Sending the MPEM out for testing/replacement. HUGE thanx to all for the great advice, I'll repost results.

 

[paulw]

Hey everyone! Finally got around to fixing this thing. Turns out the MPEM WAS bad. Nick @ Minnetonka4me had what I needed, and he fixed me right up!! After LOTS of cleaning (the hull was horribly oily and dirty and the self-baler pickups were completely plugged), fixing fuel and oil lines, and installing the MPEM I got from Nick, it fired RIGHT up! ZOOOOOM! It's still too cold for me to jump in the lake here, way up north, and I still gotta get it licensed, etc., but I cannot wait to try it out. I do still have a couple questions, though....I'm afraid to run it for more than about ten seconds at a time, for fear of damaging something, like the shaft seal, or overheating the engine. Is it possible to run the machine for longer periods with a hose hooked to the flushing outlet? I understand that this pushes water backwards thru the cooling system, but will it damage anything? I have a morbid fear of running three hundred yards out into the lake and then getting stuck because I didn't run it long enough to warm up all the way. Will running that carbon shaft seal dry ruin it? I thought about backing into the lake and just running on the trailer, but I hafta use a public launch and I don't wanna be "that guy" who blocks the boat ramp for everybody.
Lastly, I found a clear plastic hose that runs from a vent in the hull on the right hand side up front, right next to where the fuel tank vent is. It runs under the engine, back pretty close to the rear electrical box. The rear end of the hose looks broken, not cut... After poking around the manuals, I'm thinking this might be a battery vent hose....Is that right?
BTW, Many, many thanks to Nick for fixing me up! Grade A service, and super-knowledgable...Thanx a TON for sharing your knowledge!

 

[Bnelson]

Congratulations on getting her fired up!!
1. Yes you can hook the ski up and let it run on the hose..... Engine running first, then start water. Turn water off then kill engine.... That order will keep you from flooding your engine... Also a good idea to be close to the hydrant so you can kill the water quickly if the ski dies for some reason.

2. The shaft seal will heat up if ran for long, you can zip tie the metal shaft seal back to keep it from contacting the carbon ring, or can just simply keep a cup of water close and keep it wet.....
3. And yessir, you are dead on with the clear hose, that's the old battery vent hose.... Not needed unless you are running a non sealed battery :/

 

[Minnetonka4me]

No problem Paul I appreciate the business! Glad to hear you got her to fire!

I tested out his old MPEM and it was a goner.