No power in the water

[Kerlin]

I've diagnosed nearly everything with the M2, and recently bought a DDT just to be sure. It indicates the motor runs fine. There's an obvious power loss in the water even though on dry land the motor sounds normal on the hose. I'm convinced now that it must be something in the drive unit. I've pulled the stator and am trying to assess the impeller. I was hoping I would see obvious damage to the wear ring but I don't. Short of pulling the impeller and going deeper into the drive I'm out of ideas. What do you guys think of the wear ring/impeller photos? Any other ideas?

 

[philipmurphey]

Is the engines RPM's revving up but you are not moving forward, kind of like a slipping transmission?

 

[Kerlin]

Engine revs, boat moves, but sounds really rough. Doesn't feel like a slipping trans. Won't plane out but there seems to be something else going on.

 

[Kerlin]

Drained stator and drive oil, and there's no metal shavings that might indicate a chewed up drive shaft.

 

[Coastiejoe]

If the engine gets to its normal high RPMs but you are not planing out, something is slipping. Bad wear ring, stripped drive shaft,,,

 

[philipmurphey]

Did you check the gear case lube for any signs of metal or water in the lube? There are 2 screws by the intake grate, 1 is for draining and filling and the other is for a vent.

 

[Dr Honda]

1) from the pics... your impeller and housing look PERFECT !!!!!!!!!!!!!!!!!!!! BUT, if there's a small hunk of crap stuck in it... then that will keep the boat from moving. (and cause vibration)

2) You painted a nice picture in your first post... but there's no real info. (other than the pics) So to start:

a) what are your peak RPM's?
b) Is there vibration? If there is, what RPM range?
c) As the guys above have suggested... is there any point in the RPM's where it feels like you "Lose Traction"?
d) Was it running good before? (is the boat new to you?) If it was, what happened when it changed?
e) You say there "is a power loss in the water". Describe this in detail. FYI: an engine that is ready to die may sound fine on the trailer, without the pump being loaded. So, it's not a valid data point. (if you understand what I'm trying to say)


With a jet pump... they are generly tolerant of debris. I can suck in grass, and small branches, and just spit them out. But, once in a while, I will suck in something I can't pump out. (trash bag, plastic bottle, or a thick branch) At the end of last season, I was heading back to the dock (slowy) when I felt something hit the pump. When I pushed the throttle to spit it out... it was a no-go. At 3000 rpm, I could feel the vibration, and "Loss of traction". If I pushed the throttle any harder, it wasn't going to go any faster. Since it was the end of the day... it didn't mater. Once home... I got a bore scope out, and found a small chunk of crap wedged into the impeller.

I can't see into the impeller from your pics. So, make sure nothing is in there, and that there isnt' anything wrapped around the driveshaft.


Here's what crippled my boat, and made a BAD vibration.

 

[Kerlin]

Thanks for responding guys. I appreciate any help I can get at this point. I've had the boat for 4 years trouble free. Generally I put in the same lake each time that for the most part is super deep (100 - 300 ft) and have never noticed it sucking anything into the pump. On this occasion however, I pulled it to the Chesapeake Bay where you are in VERY shallow salt/seaweed water for an extended no wake zone (300-400 yards). Day one in the Bay no issues, full speed. Day 2 coasted out of the no wake zone, and as soon as clear of it I throttled up. I instantly knew something was wrong. It revved high, but unfortunately I was too distracted to notice the actual RPM at the time. I didn't hear or feel anything go into the pump. The best way to describe it is a vibration I suppose. The front of the craft raises up like its trying to pull out of the water, but vibration sound remains the same with high RPM, and it never planes. This was summer of 2014, and I've spent all of summer 15 trial and error. I've replaced all spark plugs, tested compression, replaced exhaust hoses, drained gear oil from both the stator, and the pump location next to the intake grate as suggested in a previous reply. Both gear oil locations were super clean, no metal shavings (I had just replaced both locations at the beginning of that season). I've replaced engine temp sensor, and the sensor on the opposite side of the engine temp (the name escapes me at the moment). I pulled the grate off and looked into the back of the impeller and don't see any obstruction. At idle, the engine sounds normal. I've trailered twice to test in water after doing some of this work. It sounds normal on the trailer, and in the water until throttle up. I wouldn't say theres any specific RPM range where there is loss of traction. At throttle up, it maintains the same amount of traction consistently, with the front of the craft raised up out of the water. At full throttle, it chugs along, without any noticeable jerking or slipping, just no muscle. And no I haven't gained any weight between the time it ran normally, and when it failed I hope I covered all of your questions, and thanks again for any help. Frustrated. And I agree the impeller/wear ring look good, as well as from the back with nothing around the drive shaft (that I can see). My next step is to pull the wear ring housing off to continue to dig deeper. Just for a quick test, I revved up briefly on the hose, and it won't go above 3500. I'm not educated on how the rev limiter works on land or without true in water restriction.

 

[Kerlin]

Thats crazy that tiny piece of wood screwed you up. That's why I'm convinced I need to get the impeller off to see the drive shaft chamber more clearly.

 

[Coastiejoe]

A weed wrapped around the impeller will cause serious power loss and vibration.

 

[Kerlin]

A weed wrapped around the impeller will cause serious power loss and vibration.

If your impeller is clear, then pull the shaft and look at the shaft splines.

Joe does the motor have to come out to see the splines, or will the shaft pull out after I get the wear ring housing off?

 

[Coastiejoe]

Joe does the motor have to come out to see the splines, or will the shaft pull out after I get the wear ring housing off?

Removed text as I gave wrong info. I missed that this was a Merc product. Sorry about that.

 

[Dr Honda]

coastie..... You've had your head in one too many Rotax boats. The Merc driveshaft is part of the gear box. (lol)


OK... going back to post #8...

The 3500 rpm limit was because it was still in neutral. (probably) But reving it up when it's out of the water (no load) is a VERY bad thing. It could "Run away"... and eat itself. You did answer a lot of my questions, but there is one critical data point missing... What is the RPM's when you open up the throttle full?


Since you have the stator off the end of the pump, I would take the impeller off, and make sure everything looks good. Also, turn the driveshaft, and make sure the gears feel good. If you take the sparkplugs out, it will make less resistance.



From your description of the problem... I would say something was stuck in the pump. But since it did the same thing for a few outings... then I'm not sure. (that's why I need to know peak RPM's loaded)

Since you said you checked the compression... what was it showing? (on all the cyl's)


And finally... yes... that small-ish hunk of wood made my boat run at "Limp" speed. (about 5~8 mph) It was wedged in between the impeller blades. If I spun it fast... it was making the impeller out of balance. AND... since the water couldn't flow, it would cause cavitation. Basically, the water would boil from the low pressure it caused. (can't pump water when the pump is full of air)

FYI... bad cavitation can over heat the engine too !! If you can't build pressure to push the boat... you can't build pressure to feed the cooling system.

 

[Kerlin]

Ok. I'm gonna pull the wear ring off and check everything over. Had to order a few bolts that I stripped taking off (Allen screws for stator gear oil). After I get everything back together I'll put it under load and get back to you on that. I don't recall what each compression measurement was as it was last summer, but they were all within tolerance according to the service manual.

 

[Kerlin]

https://vimeo.com/160805362

 

[Kerlin]

Hopefully you guys can see the above video. With spark plugs in it was difficult to turn. With them out it turned pretty smooth. I couldn't tell or didn't notice any damage or anything wrong with the drive shaft. Is there anything else I need to do with it while the wear ring is off?

 

[srow]

Here's a shot in the dark, when I bought my boat it had a similar symptom of idling fine on the trailer, but once in the water it wouldn't go... now I bought my boat like this last spring from a very fed-up original owner, and I never bothered to see what it was like in the water because I went straight to problem solving. However, he had explained similar symptoms to me and he had the Sea Doo Shop receipts to back it up...

After many, many hours of searching all of the things you've checked, it turned out to be a fried Trigger Assembly (TA) of all things. I don't remember the exact procedure, but all you need to do is locate the TA wire harness on the top of the engine and use an OHM meter to test resistance via the procedure in the shop manual... Mine originally read within spec, but upon further inspection of the wires under the loom, they were completely baked and corroded internally. Voila, ran like a top all summer (almost, sneaky loose fuel pump wire ruined August)...

 

[Kerlin]

I like it. I'm gonna give that a shot now. I was just researching a new ECU because I've changed every other sensor except the map sensor which is enclosed in the ECU. I don't want to spend 1700 on a trial and error. I realized I've tested/done much more than my original posts states. New fuel filters (3). Fuel tests, oil pump tests, drained cleaned tested vapor separator. Prob a few other things that I've forgotten over the past year. I had forgotten about the stator and trigger assemblies needing tested all together.

 

[Dr Honda]

Well... Mechanically, the pump and gear case look fine. So, it's looking like an engine issue.

This now comes back to the "What was the max RPM's in the water?"

 

[Kerlin]

Thank you everyone for your help so far. I'm still diligently pushing through this issue spending an hour or two a day playing with this thing. Before I drag this thing 45 min to the lake for a test under load, already knowing the problem still exists, I wanted to take a stab at SROW's suggestion and test the trigger assembly. I don't want to get my hopes up here, as I've done that several times already. I tested resistance on the trigger with my meter. Using the service manual, I attempted to read the resistance between several sets of wires on the trigger wires while unplugged. I get no response from the ohm meter. I tested the meter against itself and it's working properly. Am I missing something here? I tested the trigger with it plugged from the boat matching the colors as indicated in the book. None of the connections changed the meter from 1, or the initial display when no circuit is completed. I tried all the settings on the meter in the ohm settings, as I'm not overly familiar with what setting it needs tested on (20k, 200k, 20m etc). Same result each time, or no result I should say. Can anyone give any advise on this? Is it safe to say I need to order the new trigger? Thanks in advance for any help.

 

[Kerlin]

So...at the request of dr Honda, I drug this thing to the lake to test it under load at max rpm. After putting out of the no wake zone, I throttled up.... Immediately planed out and 50 mph. I shut it down multiple times and restarted, and it continued to run great. The only real change since the last time it was out (and failed ) is that I had it torn down to the impeller, and disconnect/reconnect stator, rev limit, ignite controller, and trigger. Maybe just a loose connection? Don't get me wrong I'm super stoked that it's running again and prior to boat season at that. But it would be nice to know what I did that fixed the problem. Thanks again everyone for your help!

 

[Kerlin]

https://vimeo.com/162008785

 

[Dr Honda]

Yep....

Could have been an air leak in the pump... or a bad connection in the electronics. But, I'm glad it's working too.

 

[Kerlin]

Dr Honda I'm hoping you're still following this post. On that last test run, everything worked great. I took the boat out yesterday for the first time since then. Pre trip, I made sure the battery had full charge, and ran in the driveway on the hose for a few minutes (no revs). Everything seemed in order and ran smoothly. Put in the lake, and started up. Ran fine for 30 seconds, then bogs down and stalls both in neutral and in gear. Did this about 10 times. tried to manually give throttle on the engine after restarting a few times but it just dies off. I took a short video of what it's doing. This morning I got up and put the rinda on it. All systems pass and everything looks good on the ECM. starts and runs like normal again in the driveway. It seems the issue is only occurring in the water (under load). Any suggestions from anyone following this would be greatly appreciated. It seemed like a fuel delivery problem but now that I'm on land I don't think that's the case. Stumped again.

[video]https://youtu.be/EQVqJPBcHWY[/video]

[video]https://youtu.be/GNi8tymGeAw[/video]

 

[philipmurphey]

I had a similar issue just recently with my 2003 challenger 1800 after a hard left turn. Had same issues that you are describing but did run fine after 30 minutes of being towed back to boat ramp. I think that the throttle guardian was flaking out and caused a "no fuel" symptom. After a tow back to ramp, it seemed to be fixed. Perhaps disconnect your guardian and see if you still get same issue.