Hello, new to the forum. I have a 96 spx that will not start. Here is the background. The machine ran fine until the ground on the battery came off when running on the lake. The boat quit running immediatley. Turns out that the mpem had fried, there was no power to anything. So I replaced it with a good used one and power came back to everything. I tried to start the boat and it turns over fine, it just won't run. I do have spark to the plugs which is why it seems strange that it won't fire up. The mpem number 278000822 I bought matches up to the one I took out of the boat #278001134. All wires were correctly hooked up. Is there anything else electrically I should check for to see if it is bad? Thanks for any suggestions.
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96 SPX - Starting Issues
- Thread starter Baldy
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Fabricator68
New Member
Like any other gas engine you need three things for it to run, spark, fuel and compression did you verify with a spark tester that you have a nice bright spark sometimes people think that they have a spark witch they may have ,it just may not be strong enough to ignite the fuel second take some 2stroke oil mix it with some gas in a squirt bottle and spray a little into the cabs and see if it fires, if it does then you know you have a fuel issue and you have to start chasing fuel lines and filter to see were the problem is ,if nothing then you need to pull the plugs and check for compression you should have about 150 in each, i seen you post that you had an electrical issue but those are the three things you need for a gas engine to run i hope this help.
Thanks for the info. The plugs have gas on them, so I am pretty sure it isn't a gas problem. I question if there is something other than the mpem, electrically that could be an issue. By replacing the mpem, could there be a timing issue that the old one was programed different from the new one. Just a thought. I have to think that if the mpem is bad and replacing it with another, the engine should start up, unless something else electrically is wrong. That is where my confusion is.
Fabricator68
New Member
Im not sure if you can adjust the timing i don't think you can, you got fuel that is good we can eliminate that, did you check to see how strong the spark is with a spark tester is it nice and bright or dim there is a part of the ignition system im not sure if it is called a magneto or something else i will have to look in the service manual that controls the spark. Im new to the pwc world i have the same seadoo you have mine has some running issues to. Im a ASE master mechanic for the past ten years but this is my first time dealing with pwc so bare with me i will do the best i can to help maybe someone else with more experience can jump in with some help.
The way you set the timing on a SeaDoo is to set the rotary valve with a degree wheel, but I think that's down the road a little as its a mechanical setting, I would think we need to look at the electrical system first.
Let me ask you a couple of questions. When you attach the lanyard do you get two beeps? Does your ski have a multifunction gauge with a digital display?
Lou
Let me ask you a couple of questions. When you attach the lanyard do you get two beeps? Does your ski have a multifunction gauge with a digital display?
Lou
I have the old style lanyard, not the dess style. It does have the digital display though and it lights up. I don't believe it is the rotary valve issue, since it ran well right up to the ground coming off the battery which blew the mpem. Is it possible I have a bad replacement mpem? Even though I have spark and it turns over? What else does the mpem do if it energizes the boat? I have been working on seadoo's for a long time, but haven't run in to the electrical issues like this. Thanks for any other suggestions.
Dr Honda
Well-Known Member
Both of the MPEM's listed are for a 720 engine... so it sould be fine. As long as you wired it properly.
If you have spark... and you verify fuel... I'd say we need a compression check. Also... we need to verify that the rotary valve is spinning.
As far as "Does the MPEM do anything else"... on that version... no... not really. It controls the power, and it's the rev-limiter, and kills the ignition by grounding the HV coil in the stator. So... if you are getting spark on both wires... it should start.
If you have spark... and you verify fuel... I'd say we need a compression check. Also... we need to verify that the rotary valve is spinning.
As far as "Does the MPEM do anything else"... on that version... no... not really. It controls the power, and it's the rev-limiter, and kills the ignition by grounding the HV coil in the stator. So... if you are getting spark on both wires... it should start.
Thanks for the information, it helps eleminate a few questions. I will do some more checking on your suggestions. I double checked the mpem wiring and it all is correct. One other thought, I read somewhere the mpem can be programed to change the timing by a couple degrees. Could this be something?
I have finally corrected the problem. After pulling off the carb. breather and determining that getting gas was not the issue, here is what happened. I sprayed carb cleaner into the carbs, even though they were very clean, the engine started to fire. After several tries and more carb cleaner, the engine fired up. I looked at the back and noticed quite a bit of injection oil was all over the driveway. There must have been so much oil inside the engine after sitting so long, that it had literally flooded the engine. A strange anomally, but it turns out it was not an electrical problem once I changed the mpem. Thanks for the help above, it helped me eliminate issues and stop chasing ghost's.
Fabricator68
New Member
That is great that your up and running at least you know the injection pump is working:hurray Mine did the same thing when i first fired it up after sitting for while i had thick back oil crud coming out of the exhaust port mine was sitting for a couple years.
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