I know this is my first post, but I've been trolling on here for over a year. I have always been able to find answers to my problems in a search, but not this time. I have a 2004 Sportster LE DI. Took it out today (second time this year). Ran great for about 15-20 minutes. Was running half throttle when it decided to shut down. No beeps, just shut off. It would restart but would only run for about 20-30 seconds before shutting off again. Battery voltage was over 13 volts when it shut off(has a gauge for voltage). Got towed in and brought it home. Starts fine on a hose in the driveway. Any ideas as far as trouble shooting from here? I'm a mechanic (cars) so I hate to bring it to the dealership if it's something I can fix myself. Rectifier was replaced last summer. Not sure where to go from here. Any help would be appreciated. Thanks, Scott
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Help with 2004 Sportster LE DI
- Thread starter STi555
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So it fires and runs without a load on it.
Let's do a compression test just to make sure where we are.
Let's do a compression test just to make sure where we are.
Dr Honda
Well-Known Member
Always a good place to start, with a 2-stroke. (even if just for general knowledge)
BUT.... if you know there was a voltage surge... then your regulator is going bad. The electronics DO NOT like over volts, and it will shut off the system. But... a voltage spike can also come from a battery cable that is loose. If the battery looses contact, the voltage will go high, when the load opens.
Also... if the voltage is just speculation... then the lanyard post could be going bad. When it shut off... was there power on the gauges?
120 is generally the lowest a ski will run reasonably well in the water.
The fact you have 90 in one hole is enough for it not to run in the water (under a load).
10% variance is the max between cylinder. 120 PSI minus 10% = 108. You are greater than 20% different.
Only thing I would do next is try a different gage to ensure accurate numbers.
The fact you have 90 in one hole is enough for it not to run in the water (under a load).
10% variance is the max between cylinder. 120 PSI minus 10% = 108. You are greater than 20% different.
Only thing I would do next is try a different gage to ensure accurate numbers.
Sportster-2001-951C-Stock
Well-Known Member
90/120 Obviously that's no a voltage surge! 
13v is a little low for a running engine, fine if not running. I bet it's closer to 12.5 now, which is where it should be.
Sorry to hear of the compression loss, any theory on what caused it (aside from the excessive piston velocity we all know and love)?
13v is a little low for a running engine, fine if not running. I bet it's closer to 12.5 now, which is where it should be.Sorry to hear of the compression loss, any theory on what caused it (aside from the excessive piston velocity we all know and love)?
On my way to borrow another compression tester just to verify. The voltage was 13.5-13.7 when running sitting at 12.7 now. I had it out about a month ago and it did the exact thing. Would the compression loss let it run for a while then quit? I noticed the brand new plugs were both fouled. Did it just run till the plugs fouled out? Will run another compression test and update. Thanks for the quick replies.
With low compression if every thing else is in GREAT condition they will normally run. As the plugs fouled, you likely lost any chance of it running.
Sportster-2001-951C-Stock
Well-Known Member
Yeah, I know mine (carbed model, of course) regulates really tightly, I don't think it went over 13.8v while running, I measured it out of curiosity and now of course forgot exactly b/c I didn't record the value. Probably hadn't been running more than a couple minutes, so not much of a test. It definitely doesn't overcharge the battery, and probably not enough voltage to properly charge a deep cycle battery but it seems dead nuts right on for charging a cranking battery.
I don't think low compression is going to cause your boat to up and quit like the key was turned off, more like make it hard(er) to start in water and possibly foul plugs (because there isn't enuff compression to completely burn the fuel). possibly rough idle. In that case the next hotter plug might reduce fouling, an old indian trick.
Check that connector #3 on the MPEM, maybe the power feed is loose? Could even be the stop switch is corroded internally and actually made, a valid signal to MPEM telling it to shut 'er down. DESS post as well, could do that. I just LOVE that DESS to DEATH! (My neighborhood isn't exactly full of hoodlums hiding behind trees waiting to steal my boat, unfortunately).
Oh, and don't overlook the ground post in the rear e-box where several grounds are all tied together and held tight by a screw threaded into a plastic post. I have a plan to drill mine out through the bottom and install a stainless bolt, nut (with a washer underneath) some day.
What hurts worse than anything is to see a mechanic stuck out on the lake with a dead boat, LOL, not sure what to think of that one.
I don't think low compression is going to cause your boat to up and quit like the key was turned off, more like make it hard(er) to start in water and possibly foul plugs (because there isn't enuff compression to completely burn the fuel). possibly rough idle. In that case the next hotter plug might reduce fouling, an old indian trick.
Check that connector #3 on the MPEM, maybe the power feed is loose? Could even be the stop switch is corroded internally and actually made, a valid signal to MPEM telling it to shut 'er down. DESS post as well, could do that. I just LOVE that DESS to DEATH! (My neighborhood isn't exactly full of hoodlums hiding behind trees waiting to steal my boat, unfortunately).
Oh, and don't overlook the ground post in the rear e-box where several grounds are all tied together and held tight by a screw threaded into a plastic post. I have a plan to drill mine out through the bottom and install a stainless bolt, nut (with a washer underneath) some day.
What hurts worse than anything is to see a mechanic stuck out on the lake with a dead boat, LOL, not sure what to think of that one.
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Sportster-2001-951C-Stock
Well-Known Member
Could be a heat soak phenomenon as well, as if it runs until engine compartment heat builds to a certain level then something electrical breaks down.
Wish I'd have thought of that yesterday while I was rowing for two hours. Have spare plugs and tools on the boat. Guess I was assuming it was an electrical problem. At least I got a good work out.
Just look at all those calories you burnt off...
Second compression test: 75/105. I'll go with the first test not that it makes much difference. Variation is still the same.
Checked battery and ground connections. All tight. All connectors on the MPEM as well. How do you test the DESS post and start/stop switch. When it shut off I don't think the gauges turned off. I didn't do anything with the lanyard, just pushed start and it started for a few seconds.
Checked battery and ground connections. All tight. All connectors on the MPEM as well. How do you test the DESS post and start/stop switch. When it shut off I don't think the gauges turned off. I didn't do anything with the lanyard, just pushed start and it started for a few seconds.
I'm feeling it today.
Was thinking something similar. Thought maybe it was over heating but I thought I would get some kind of warning.
Coincidence the post below mine is for Sea-Doo Engine Shop? Looks like I need to address the compression issue before going any further. Any recommendations for a good rebuild? I can pull it out and put it back in but don't want to try to tackle a rebuild by myself.
P.S. Thanks for not flaming me for posting in the wrong forum. Any way this can be moved?
P.S. Thanks for not flaming me for posting in the wrong forum. Any way this can be moved?
From my readings, most go with SBT. And,, most members suggest getting the 1 or 2 year no fault coverage,,,
Sportster-2001-951C-Stock
Well-Known Member
A continuous beep is the warning signal from the MPEM, RPM's will be limited and it will throw a code, the water temperature sensor(WTS) is mounted on the cylinder head. The resistance of the sensor(presumably at ambient) should be between 2740 and 2280 Ohms.
I'm not sure if the MPEM uses this sensor to control air/fuel mixture, it might.
Here's the electrical schematic for the DI in the RX ski, for 2001 model year:
Attachments
Sportster-2001-951C-Stock
Well-Known Member
If the gauges remained on, then it makes me lean me away from an electrical problem a little.
This kind of makes me wonder if it may have seized, considering the compression is down. 2 stokes are seize-prone if compression is low due to wear(rings and bore clearance) because the oil film is more likely to break down due to piston overheating from blow by and reduced conduction of heat out of the piston crown by the rings. (clearance tolerance and ring seal play a huge role in conducting heat out of piston, especially on direct injected engines).
If you obtain another engine, make sure to get the correct year bores b/c the port configurations were changed at least once through the years and the MPEM fuel map was recalibrated for the new port configuration. Mix and mismatching the MPEM map with cylinder port configurations will give you a flat throttle/miss somewhere up in the cruising RPM range. There's a service bulletin on this subject and it's been known to happen on motor replacements.
You MAY have an electrical issue that presented itself when it shut down.
But you most definitely have an engine issue as well.
But you most definitely have an engine issue as well.
Sportster-2001-951C-Stock
Well-Known Member
Correct, it's quite possible he may even have a defective MPEM which is why if it were me, I would attempt further troubleshooting as opposed to ordering up another engine just to discover the MPEM is also bad.
Unless of course he likes the boat well enough to replace both, if need be.
I agree in that, if you have an issue now you WILL have an issue even with a new engine. Do you NEED engine work? Yes.
If it were me I'd confirm all electronics are good to go so you are not fighting the initial issue after the engine repair.
That said, it is hard to test some things if the engine won't run due to compression.
Kind of a bad spot to be in.
What kind of trouble shooting can be done on the MPEM? I would like to rule out any other problems before spending any $$$ on it. Put new plugs in it yesterday. Going to run it on the trailer in the water and see what happens if it ever stops raining.
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