03' Sportster 947 951 carb'd won't idle and only starts at full choke, even when warm

[tasman]

I know it sounds more simple than it probably is, but this thing is driving me crazy. Ran a little rough when I first bought it a few months ago, but no problem starting right up every time, even without choke mostly. Had the SeaDoo stealer tell me there was water in the engine when he dewinterized it which is funny because they are the ones who winterized it last fall, but regardless it seemed ok when I got it in the water the first few times and I was getting 55mph out of her at about 7000rpms. Oil got low, so I added 2 stroke oil I found in a marina when I was gassing up that said on the side that it was fully synthetic 2 stroke oil suitable for auto injecting Sea Doo engines. My existing oil was only 3/4 depleted so adding this new oil potentially created a whole new situation in my oil tank. About 45min to an hour of engine running later the revs were ridiculously limited and I barely was able to sputter back to shore with smoke coming out of my exhaust (though not very dense smoke, just like you'd see if it was running very rich). The situation got better, then worse, then better, back and forth for a couple of days, then just stayed in the dump where it is now. I am currently halfway down on my oil tank and can only get up to 5700rpms or so topping out at about 40mph. WTH??

I took it to some terrible mechanics who rebuilt the carbs but this did not fix the issue. I took the boat back from them after 2 weeks of "looking for an air leak" and nothing. Is it possible that the oil could be the issue and a flush of the system is needed? or is my adding oil and subsequent drop in performance unrelated? I did check the entire system for water leaks, cleaned the RAVEs, disassembled entire exhaust system and inspected for blockages etc, cleaned air regulator on the muffler housing, replaced exhaust manifold gaskets (after reading about water leaks), checked fuel filter and fuel lines, all seem to be ok. I don't have alot of the testing equipment you seasoned folks do but I can tell you the compression was tested pre-carb rebuild and it was 120-130 as I recall which sounds pretty good. I did test the engine under several conditions as well - I tried running with gas cap vented, air intake off the carbs (so I could watch for water leaks) and with the exhaust removed, none of these made any difference, it still would not start and idle, and would not start without full choke.

This is not the DI model so I'm not sure if voltage or air compressors are a big issue - again, it would have to be pure coincidence wouldnt it? This motor has about 100 hours on it I think. The raves were really nasty with sludge so I would guess a rebuild is in my future but again, this thing was running pretty well just a few engine hours ago.

Any ideas? Thanks from a first time boat owner

 

[Dr Honda]

Welllllllll....................


Just going from your title...

1) The pilot circuit in the carbs is plugged. It's your idle fuel. SO... it won't idle... and it won't start without the choke.

AND/OR

2) the idle is simply set way too low. (But the choke won't normally help that)

AND/OR

3) You have bad reed valves.




I'm very sorry about the bad dealers and tech's... but that's why we are here. The pro's give the novice's free advice to fix their engine. (and save $$$)


If this was my ski... I would pull the carbs, and the reed cages. (They are directly below the carbs) The more I sit here and think about it... I'm betting you will find a broke reed in each side. (I'm going to assume the carbs got rebuilt properly at the moment)



Last thing... just as an FYI... NEVER trust anyone about the oil for that engine. It's very specific. You need a full synth that is API-TC APROVED ! Not compatible, and not "Meets or exceeds". When you see that... it's not actually been tested. SO, unless you read the label yourself, and see the certification... don't put it in your ski. Also... mixing 2-stroke oils is a bad idea. (as you eluded to) Here again... if it was mine... I would drain the oil tank, and refill with the right oil. (and I would change the filter too)

 

[tasman]

Welllllllll....................

Just going from your title...

If this was my ski... I would pull the carbs, and the reed cages. (They are directly below the carbs) The more I sit here and think about it... I'm betting you will find a broke reed in each side. (I'm going to assume the carbs got rebuilt properly at the moment)
)

Well the reed valves is the last piece to this puzzle that I have NOT explored and obviously a major pain to get to due to all the stuff I have to take off to get to them....The guys who did the carb rebuild used a kit and they do alot of skis all summer long so I am assuming they can do the basics properly. They DON'T have any expertise however in Sea Doo and certainly not in 2-cycle carb vs DI or any of the many nuances. I do think that they set the carb idle speed and all other adjustments the same as before because essentially the engine ran the same before and after the rebuild. If I hadn't seen the carbs out and on the bench being rebuilt with my own eyes I might have doubted the work was done.

The dealer wanted to charge me ~$850 to replace the entire top end to address their "suspicion" that there may be water in the engine. That diagnosis was made without opening up anything and even taking a look inside. Ridiculous.

I'll post later after I've swapped out the oil and put an hour or two of run time on it....Like I said, I know I have a rebuild in my near future, I just want to get through the next few months with it performing modestly well - our summers are so short here in upstate New York.

 

[Dr Honda]

..........................The dealer wanted to charge me ~$850 to replace the entire top end to address their "suspicion" that there may be water in the engine. That diagnosis was made without opening up anything and even taking a look inside. Ridiculous.

.................- our summers are so short here in upstate New York.

OM F-ing G !!!!!!! they "Suspect" water in the engine.?!?! Then pull the pugs... crank it clear... put a little raw fuel in it... and fire it up !!!! as soon as it starts... water is gone.

At that point... if there is damage... the engine will eat itself. But regardless... if things seem right... that that's NOT the issue.



I understand about the short season. Im in Pitt PA, and with all the rain... even the nice days are hard to get on the water. Today... is perfect, but all the local ramps are closed due to high water, and debris.


FYI... the compression is a little low at 120... but it should still run.

 

[tasman]

ok well update from today - I flushed all the old "black" oil from the oil reservoir but only up to the point where the oil filter is in the line - I replaced the oil filter and flushed the line up to the filter using almost a whole gallon of the recommended XPS - though I did note that even at the end there was streaks of black in the red XPS oil that was bleeding out of the line, so I had to say at some point that enough is enough when it comes to flushing. No noticable difference right away on dry land as expected.

Water test a few hours later - throttle is noticably more responsive to changes and engine genuinely feels like it has new life breathed back into it, though it still will not idle and the high end of the rpm range is limited to about 5600rpms and the engine sounds like it is being starved of air. Does not feel lean at all, actually the opposite. So, top speed is still limited to 39mph approximately. I can't help but feel like the RAVEs aren't opening up like they should, but I'm not sure how to test that without somehow attaching a gauge or something to the solenoid to test voltage and/or air pressure in the lines that trigger the RAVEs. Bigger issue is how do you do that at 40mph?? I feel like i'm going to go head over heels into the engine compartment trying to take readings or even pinch air lines with my fingers to feel pressure at those speeds.

Is there any way to really tell if the RAVEs are open or closed? even if the solenoid is triggering them to open, an air leak or something else could be preventing them from opening right? How would you really know for sure? Should I try adjusting the spring tension on top of the RAVEs to see if that makes a difference? I did not change them from factory when I cleaned them.

To anyone wondering about the health of your oil, I'd say if it is not a healthy maroon tone, you might need to flush the tank. Sea Doo XPS full synthetic 2-stoke oil should be dark red in color. Lesson learned!

 

[tasman]

Agreed - Their quote included $600 in parts including new pistons, gaskets, RAVEs, essentially a whole top end rebuild. This is a busy dealer that sells pretty much scarabs in their showroom and a few other smaller lines. But what do you know, they are the only Sea Doo dealer in the area so I'm kinda out of luck. I said pretty much your exact comments to the head mechanic there about water in the engine....I opted to take it out for a water test myself and maybe consider his quote later.

Soooo glad I found this forum.