'05 3D 787rfi engine runs/revs outside water, bogs/ no acceleration in water? pls hlp

[Ilovehotdogz]

Hi, I have a 2005 seadoo 3d w/ the 787rfi engine. Outside of the water the engine fires up, within 2 tries, revs up and sounds good. I can post a video if it will help find issue. I dropped the ski in the lake today, took 3 tries to fire up, yes I started it before I put it in. It wouldn't idle in the water so I held throttle 1/4 to keep it going, it did about 4mph, when i pulled throttle all the way down it would not rev up, maybe jumped to 7mph and almost sounded like it was going to die so I left off and kept it 1/4 and kept trying to do more, in 10min it never shut down on me but wouldn't go any faster, it was like this the whole time.

It has new plugs, fresh gas, and new fully charged battery. After I took it out of the water, I fired it up took 3 tries and it struggled to start, the more water it pumped out of it the better and better it started sounding and then it started to rev up again and sounds pretty good, wth? I've read a lot of posts on here and have ideas but not sure and hoping to get others input?

could it be a small clog in the cooling system? where do I start to look for that, from the outside the hoses, elbows, t fittings look good, they don't look shrunk, melted or otherwise not right.

I took all the exhaust out, did a short pipe mod. The 3 water adapters on the bottom of main exhaust housing looked good or at least clean, easy to blow through them. last year replaced the regulator as when I checked seemed to have low voltage, the new one is great and reads right, so I don't think its that.

any help or ideas of where I can continue to fix this problem. in this post someone talks about the rave valves and causing there 04 to bog down, they say the rave valves should be screwed in all the way or at least flush with the black tops. I've cleaned my valves, they look very clean, no carbon but the red piece is screwed about a 1/5 inch past the top of the black nozzle, could this be the problem? super easy fix if it is, just unscrew them, if so why does it work outside of the water but not in the water, is it due to back pressure in the exhaust then? http://www.seadooforum.com/showthread.php?8296-Sea-doo-3d-lack-of-power-(Bogging)-problem

I can post pictures/ videos of anything you guys think will help you help me diagnose and fix this problem. Thanks in advance for any help!

there is a black sludge in the back of the ski? like a mixture of water, oil and exhaust? can be scene in pics -

 

[Dr Honda]

What you are describing can be a few things....

1) Low Compression: When the compression drops, it won't make any torque. Check it, and let us know what you get.

2) A bad Rectifier: If AC is passing, or the voltage goes high, it will do strange things. Remove the red wire from the rectifier, and try to run it again.

3) Bad fuel injector(s): if they are leaking, or stuck... the engine wont run right.

 

[Ilovehotdogz]

today I cleaned, blew air through cooling hoses, and checked anything out of place. As for #1 low compression, I doubt but haven't checked yet, it revs pretty high, for low compression I have my doubts it'd rev that high.

#2 replaced rectifier with a brand new, voltage looking perfect... guaranteed to do its job right

#3 fuel injector are located under engine side and hard to see it feels good and I doubt these are the problem as well, doubt this but don't mind checking in long run


Continued: I cleaned today and I read about the rave valves/ bellows, the RED part on the 787rfi should be flush with the top of the black over cover, mine were screwed down as far as they could go, 1/4 inch passed, after I unscrewed them to flush level, the dry fire sounded good, slightly better than before, I tried to pull off both bellows and found it impossible to pull off Front piston, or left piston bellow to clean, without removing main exhaust, are you kidding me???? thats rediculous.

Question - Can i spray carb cleaner into/ below the bellow the help clean the carbon on the front rave valve or do I absolutely need to remove it? if I do, does anyone know how to remove it, (2005 3D 787rfi) without removing the exhaust, pics included you can see the front valve squandering under the pipe, what a joke... in the last picture the bellow doesn't clear the header/ exhaust manifold? how do I clean this without removing/ getting a new gasket exhaust manifold?

 

[Ilovehotdogz]

So a continuing update - I was finally able to remove both bellows and rave valves and cleaned them thoroughly. I put them back together and when I fired it up, it sounded perfect, I was excited, so I went to the lake and dropped the ski in and..... nothing, ski took at least 5 tries to fire up and when it did it would not go about 5mph. sounded like it was only running on 1 piston, when I pulled it out and dry fired it, as it spit the water out it started sounding better and better till it sounded perfect, ughhh.

So any other ideas as to why it doesn't work in the water but sounds fine outside of the water? could it be the cooling system?

Tomorrow I might try pulling the exhaust all out and checking all water lines again, any other ideas would be much appreciated! I will keep you guys updated, I've got plenty more pics, as for anyone wondering about getting the bellow out that sits under the exhaust, it ridiculously hard and a real pain, but does come out without removing exhaust.

could it be the wear ring? if so why does it work outside of the water, is there a sensor?

 

[Seadoobuddy]

Sounds like low compression ratio......check it now before you start replacing things that aren't broke in a wild goose chase.

 

[Dr Honda]

With out a load on the engine... it will rev, even if the engine is about ready to die.

Before you go to the trouble of looking for another problem... it really sounds like low compression. You can get a tool for around $20. Or... you can rent it from a place like autozone.

 

[Ilovehotdogz]

Checked compression:

Front piston peaked at 110psi and repeated consistantly but started low 1st hit was a little lower maybe 70 it was hard to be see exactly

Back piston peaked at 140psi and repeated consistantly but 1st hit was also low.

Rear spark plug was black and oily, ski smoked heavily when fired up, more than normal.

What psi should the pistons be at? is the heavy smoke from bad injectors? does top end need rebuilding? thanks for your guys help, hopefully getting somewhere with this!

 

[Dr Honda]

The 800 Rotax engine should be 150. So, it sounds like there is damage to the MAG piston. (time for a top-end)

 

[Ilovehotdogz]

thanks for that info. What is the MAG piston?

can you lead me in a direction to a Top End kit besides ebay, the seadoowarehouse has all the parts but its all individual? if i'm doing a top end should I replace the injectors as well?
a quick google search on pwctoday forum, a guy running a 787 on a older ski, said both pistons were pumping 110psi and he said it ran like a champ? I don't mean to offend anybody here or question your opinion I'm just trying to gather as much info about this as possible, in my experience on 4 cycle car engines, when you lose a little compression you can still drive it, engines can be pretty shitty and still function.

 

[Ilovehotdogz]

UPDATE: ski problems/ engine/ and fixing....

I pulled the top end off, and front piston rod; had way too much play/ movement among other problems... the front cylinder head was clean of any carbon and almost looked hardly used, you can see it in the pictures. There was about 4 quarts worth of oil/ water gunk underneath the engine, also seen in pictures.

There is a crack in the bottom of the exhaust near a water jacket, seen in pictures. So I've decided to tear the whole ski apart, which I've done and pulled the top end off as well as the bottom end, going to do a complete rebuild as it will need it if I want it to last any amount of time.

I've posted a link to photos from dropbox, hope it works, cause I've never used that before and it was easier than emailing myself photos than uploading them on here. 41 photos so far and that's a lazy amount of whats really been done so far, hard to take photos with dirty hands. Please let me know if you can access photos?

https://www.dropbox.com/sc/bdn0t9he64t3p55/YK3ll-Arg6

So far I have the entire engine apart and in pieces, I've been told to buy a professional rebuilt crank? rather than try to rebuild my own? anyone have an idea where to get one?

as for pistons, getting new pistons, rings, bearings, honing cylinders as there in great condition, no real serious problems, micro-mitered to specs, oem pistons so no boring as it doesn't need it.

Monday/ tomorrow I'm going to a shop to weld the exhaust back and check it for internal water leak, or if its just on the outer shell, either way getting it fixed, I'd do it myself but it says it requires a tig welder which I don't own, anybody know a good price to pay for a job such as that?

Soon to happen: i'll check fuel injectors, fix exhaust leak/ crack, new crank shaft, new top end and I think thats about it, everything else I've looked at seems to be in good/ great working condition. One problem as I've torn this thing apart I still ask myself is what caused all this in the first place? I believe there was a water leak in one of the cylinders, or gasket failure that's why the front piston cylinder and dome/ head are free of carbon and look hardly used, as water inside will break the carbon off, basically cleaning them or ridding them of carbon at least. Due to this caused unusual tork on the rod which over time caused the rod bearings and crankshaft to wear poorly, in time it would have thrown a rod. I'm assuming that's why outside of water it sounds great and fires right up, but once in water it drowns front piston. There was water in the crankcase when I pulled it apart.

I thinks that's all I got for now and will keep you updated as the rebuild comes along, I'm ready to start ordering parts? Have any ideas where to lead me too, I've been told to stay away from SBT, some websites says they don't even allow SBT blocks back as a core... Not a good reputation for that company! new top end kit? crank? gaskets? injectors (if needed)? new oil filter? I've asked an ample amount of questions in here scattered through out, any help would be much appreciated, thanks in advance and thanks for reading!

 

[Ilovehotdogz]

Final Update and Review

So after about 50-hrs of slow work and countless time waiting for parts, ski is done and runs like new.

I asked/ sent a PM to a couple members on here asking about SEADOO parts etc in hopes to find a good direction to go, and got no help from anyone on here, minus the few replies to this thread, just fyi that's super lame...

seadoowarehouse is like buying from a dealership, just oem parts woohoo how exciting...not really
Anyways, after lots of calls I ended up going with PWCENGINE.COM and highly recommend them to anyone looking for parts.

I bought their rebuilt crank for 300, W/ 1 year warranty, new bearings, seals, with writst pin bearings on Rods
http://www.pwcengine.com/products/Seadoo-787-RFI-Rebuilt-Crankshaft.html

Pistons & rings from pwcengine.com for 80 Platinum WSM:
http://www.pwcengine.com/products/Seadoo-787-RFI-Piston-Kit.html

and new oil filter from pwcengine.com for 8?

I bought a complete engine gasket kit off eBay for about 60 I think, came with 3 different thicknesses for base gasket for different compression's, cool but I only needed factory/ standard as I'm not racing this thing, just want it to work right.

I bought the necessary Loctite, red, blue and anti-seize from a local hardware store, in the manual it calls for Molykote, which sells for about 45 from our local Seadoo dealer, i talked to a sales guy who said yep have to get it, then went to the back and talked to 2 different mechanics who said they never use actual Molykote but instead use just a regular Synthetic grease. So from the local hardware store, i think O'Reilly's I got the 3 different locetites and synthetic grease and a gasket sealant for about 40. Had I gone through the dealer it would have been about 140.

Total cost of Rebuild:
Crank - 300
Pistons - 80
oil filter - 8
Shipping - 40

ebay Gasket kit - 60
-free shipping

locetite sealants - 40

============= 528

plus fixed crack in exhaust, had a Yamaha shop weld a 4 inch crack in exhaust for 71 and pressure check it for any leaks, looks perfect.
There was a handful of other small costs, like high grit sand paper for cleaning, gasoline for cleaning, chemicals to break bolts loose etc... tack on another 50 on the high end. I also checked the Oil pressure and the Fuel pressure not the easiest things to check but do able, they both looked perfect, thankfully... had either of those come back bad, tack on anywhere between 200 to 600, lucky me! http://www.seadooforum.com/images/icons/icon6.png

so Total rebuild cost = $649

maybe 60 hours of your own time if you work slow and are meticulous. If i had to do it again, I could probably do it in less than 30 but I took my time and made sure to do a great job. I'll post the manuals I used, at times I also used the seadoowarehouse.com to look at sections of the engine and how they should be taken apart, it is good for that!


I cleaned the entire ski inside and out but have not got pictures of engine installed yet, it looks real good though and runs even better. I've logged about 12 hours on the ski, maybe 25 gallons of fuel, followed break in theories to make an engine last that said for the first 10 hours never go full throttle but constantly adjust throttle. Took it very easy on the ski, those were very boring hours but necessary to assure this engine and assure this quality rebuild.

In the manual it says that not all water will drain out of the ski, so in winter time you must add antifreeze into the coolant hose, honestly that just sounds stupid, fogging engines/pistons is one thing but adding antifreeze, comon' that's a joke right? I had never done that and believe that the remaining water froze and split a part of the gasket that allowed water to swamp the piston, that is why it didn't work in water but sounded perfect outside of water. I thoroughly checked all the parts of the engine for any more damage as well had it checked by a close pwc mechanic for rebuild quality inspection. Another thing, in the manual it says, "after the engine gets warm during operation, it only idles on 1 piston making idling irregular with lots of smoke." IMO poor choice. the 2nd piston starts up at 2300 rpms, easy way to foul a plug, poor design, IMO.

Please take everything I've said with a grain of salt as its just my opinion, I have done a high quality rebuild and understand this engine very well, and IMO it is not a well designed engine for my taste or at least for me as I live in Colorado where temperatures freeze and I do not have the luxury of storing my skis indoors.

As of now this ski rips on the water and is a blast to ride. I will continue to use it for the rest of summer and following. I have no doubt, this ski could last forever when cared for properly. It pulls hard and planes quickly. http://www.seadooforum.com/images/icons/icon14.png

I'll try and post a couple pictures of the engine in the ski later, attached is the engine slightly before installation. The last picture is of a contraption I devised trying to remove the coupler from the crank. Drilled to holes through a 2x6 put the rods through the holes, put a stick that fit perfectly through the rod holes, then drove a car on the 2x6, bought 2 grade 8 bolts from ace that fit the coupler relieve holes, haha and honestly it was over 300 ft/lbs of torque before it broke loose, I know this seems over kill but it was the only method that worked to get that part off, the tool used to remove it, with the lock on the magneto side was unsuccessful. If you have any questions, comments or concerns about this ski or your own, feel free to ask. I honed the cylinders as they were in great shape and measured to manual specifications within spec after honing/ cleaning.