787 - More Issues :(

[dean.mohr]

1997 GTX. Had a hesitation at 5000 rpm. Tried cleaning and adjusting the Raves, no luck. Messed with carb settings, no luck. Rebuilt the carbs (including seat and needle) and reset them back to factory settings, no luck. Replaced with updating rave valve housing (that does not have the slot per the TSB for 1997 rave valve caused hesitation at 5k rpm) and now it hardly wants to run. Acts like it isn't getting fuel. Would take off and briefly hit 6500-7k rpm, then wobble and slowly drop down to about 4500 rpm. After a few attempts at making rave adjustments on the water, I set them back to screwed all the way (how I had them before I changed the housings) and it wouldn't hardly run. When I left off the throttle, it quickly dropped to 800 rpm then stalled.

What on earth could have happened? I took it for a test drive in between rebuilding the carbs and replacing the rave housings and it was not doing this. The ONLY thing that changed was me replacing the rave housings. I think I'm going to start with pulling/changing plugs and pulling the carbs back off and making sure I have a clear return and supply lines. All fuel lines were replaced long before I owned it.

 

[pwgsx]

Did you replace the rave valves to the one with the slots in them?? The TSB is for the valve AND the bases. Also check your water reg and see of its working right. I just went through this on the same ski but a word of advice, test and fix one thing at a time. IF you start messing with carbs and fuel and then screwing rave caps down more you wont fix anything but make more work. If its not running at the factory settings, something is wrong and randomly adjusting stuff is not going to fix it

 

[dean.mohr]

Did you replace the rave valves to the one with the slots in them?? The TSB is for the valve AND the bases. Also check your water reg and see of its working right. I just went through this on the same ski but a word of advice, test and fix one thing at a time. IF you start messing with carbs and fuel and then screwing rave caps down more you wont fix anything but make more work. If its not running at the factory settings, something is wrong and randomly adjusting stuff is not going to fix it

I only replaced the housings because... I don't know why. But I only did housings. Didn't figure the valves would make that big of a difference since my 2000 uses valves that look the same (don't have the slots in them) and works fine.

I replaced the water regulator a few weeks ago when I found that the bottom clamp was gone and it was leaking. Didn't work.

I've been trying to fix one thing then test it. That may not have been entirely clear in my initial post, but I have tested after each attempted repair.

 

[pwgsx]

Yea you need the valves with the grooves in them as well. Try that and I bet it will work.

 

[dean.mohr]

I will do that then! Good thing I'm made of money... /s

 

[nisjeep]

Did you use Genuine Mikuni kits? Check the tiny intake filters. Can be hardened pump diaphrams aswell.

 

[dean.mohr]

Did you use Genuine Mikuni kits? Check the tiny intake filters. Can be hardened pump diaphrams aswell.

Yes I did, everything genuine. Before I replaced the rave housings, I took it out after rebuilding the carbs and aside from the 5000 rpm hesitation, it ran fine. So I don't believe it is the carbs.

 

[nisjeep]

Still sounds like fuel starvation to me. Maybe something came loose after rebuilding ? And a dodgy fuel pump.

 

[pwgsx]

No he updated the rave bases and not the rest. They are not working at all now.

 

[mikidymac]

All of my 787's don't have the slotted RAVES and run and rev fine.
Just saying it can cause issues but it doesn't always.

Easy way to check is make sure they slide easily all the way out then run it without the caps. You will have a big flat spot at low RPM but should pull all the way to 6900.
If this works then you know the RAVES are sticking. If it is still stuck at 5000 then you have eliminated the RAVES.

 

[pwgsx]

Not sure but it only was for the 97 GTX, SPX, GSX. I actually just had the same ski in my garage with the same issue last week. I changed out the base and valve to the new style and it worked just fine.

 

[soccerdad]

Hey Dean,
So I did not go back and find your other thread. Sorry you have so many issues. So way back to basics. Not sure what you have done, but here are some things to think about.

It does sound like a fuel delivery issue. So I would start by bypassing all the fuel lines and run one directly from the RES nipple on the fuel baffle to the inlet on the carb. This will make sure there is no possible air getting into the system. Then test. If that does not work, then crack open the gas cap to make sure it is not creating a vacuum in your tank. If that works, then you have a vent clogged.

Other options to look at is to remove the red wire from the voltage regulator to see if that helps. And I assume you have good plugs and the other basics.

 

[soccerdad]

1997 GTX. Would take off and briefly hit 6500-7k rpm, then wobble and slowly drop down to about 4500 rpm. .

So if it was able to climb to 7K, I think the raves are working. The slow down seems like you are running out of fuel or volts.

 

[dean.mohr]

Now that I think about it, it does have the 12V low flash on the display when I first try to start it. It charges just fine though and the battery isn't low. I assumed its a starter issue since sometimes the solenoid won't engage and I have to click the start button 2 or 3 times.

Either way, valves ordered. Normally I'd try any of these things, but it seems to me that it would have to be the raves since that was the only thing that changed in between it working and working very poorly. I may still try to mess with the fuel selector/bypass it just to see.

 

[dean.mohr]

When I pulled the ski out of the water and fired it up on land to clear water out of the exhaust, it didn't want to run at first, but after a few prods of the throttle it was revving like normal and hitting the limiter. I realize that out of the water this may not mean much, but I wonder if my recent (a few weeks ago) replacement of the water regulator could be affecting this?

 

[pwgsx]

You can remove the hose from water reg to pipe and hold it overboard. Start accelerating and the water stream should be high and then almost cut off at a certain rpm. If it stays a hard stream through the whole rpm range its bad. Dont drive like this for a long time as it will overheat your pipe. Just make one pass and see what it does.

 

[racerxxx]

When you replaced your water control valve/regulator on the water box, did it discolor the water box and stinger? Check the exhaust hose FROM the water box to the EXIT of the hull, if that hose got hot enough it can collapse internally and choke off the exhaust. Long shot, but worth checking.

 

[dean.mohr]

When you replaced your water control valve/regulator on the water box, did it discolor the water box and stinger? Check the exhaust hose FROM the water box to the EXIT of the hull, if that hose got hot enough it can collapse internally and choke off the exhaust. Long shot, but worth checking.

That one is fine. Still very springy and clearly not collapsed.

Still waiting on my parts to show up.

 

[dean.mohr]

So as I was putting everything back together yesterday, I noticed something... the spring in my water regulator was broken - both on my old one and the (used) replacement I had purchased. The spring had snapped and was sitting kind of inside of itself, ultimately putting very little pressure on the top of the regulator. I'm only so familiar with the function of it, but it sounds like that could result in it dumping extra water in to the exhaust, causing lots of back pressure?

 

[dean.mohr]

Alright. A little update:

Replacing the spring in the water regulator did nothing. Still hardly wanted to run in the water. When I got home that day, I cleaned the spark plug boots and trimmed the wires to make sure I was getting a solid connection. Also made sure I put the new, fully charged battery in. Still no luck. The first few times I tried to start it, it started right up but when I applied throttle it struggled and back fired hard. After a few tries it would stay running, but even out of water it clearly didn't want to rev much.

I pulled the carbs off last night again just to make sure something hadn't gone wrong (torn diaphragm, loose line, etc) that would have limited fuel delivery. Of course, everything looked good. I didn't even bother restarting the thing because I knew nothing would have changed.

Just for fun, I pulled the head off. Found the PTO cylinder head was spotless, a sure sign of water intrusion. Nothing seemed wet, and the cylinders and pistons look great - no hot spots, cylinder walls are smooth with no visible or tactile grooves. Pistons are black on top, but I believe this engine has between 230-280 hours without a top end kit. I'll try to clean them up a bit before I close the head back up. I couldn't find any evidence of a bad/split/rolled seal or gasket, but I'm pretty confident that at some point recently, there was water in the cylinder. My elementary understanding of the function of the water regulator leads to me to believe that there really shouldn't be a way to it to send water into the cylinder(s). When I lasted tested compression (when it was running ok) I was around 135 in each cylinder, but I haven't tested it since I started having the most recent issues.

I figure since I have already pulled the head off and have a potential water leak, I want to do a top end seal kit. (I'm not interested in a full top end kit as not only does it not seem to need it, I plan to sell this and don't want to dump a bunch of money into it.) Also, the spark plugs look awful now, so those will be replaced, as well. Anyone have any other suggestions? Is SBT okay for the top end seal kit, or should I source SeaDoo parts only?

The marks in the middle of the pistons are just from me pushing them down.

 

[bjg214]

That's a long time to go without a top end build. These motors should be showing much closer to 150-155 psi per cylinder during a compression test. I just recently finished a full restoration of the same ski. One of the biggest headaches was learning that my mag cup had lost it's magnetic properties and was causing the ski to run real weird, I wonder if you might have the same problem. Either way, if you're trying to sell, it might not be a bad idea to have the top end rebuilt so you can sell easier and for higher value.

 

[dean.mohr]

That's a long time to go without a top end build. These motors should be showing much closer to 150-155 psi per cylinder during a compression test. I just recently finished a full restoration of the same ski. One of the biggest headaches was learning that my mag cup had lost it's magnetic properties and was causing the ski to run real weird, I wonder if you might have the same problem. Either way, if you're trying to sell, it might not be a bad idea to have the top end rebuilt so you can sell easier and for higher value.

Admittedly, the whole ski is pretty rough. I just want rid of it so I can make room on the trailer for something a little newer and nicer (and faster!)

I wasn't so worried about the compression test number as the 2 cylinders were even. On my '00 GTX (951) it read like 115 each, which I'm quite confident isn't correct since it still runs great and reaches its prescribed top speed. Cheap compression tester...

 

[bjg214]

Have you checked all your wiring harness connections? The main harness I had coming out of the mpem was pretty fouled up (one of the issues we fixed while tracking down my electrical problem) and it definitely helped some.

 

[dean.mohr]

Not specifically, no. I went through some of the easy stuff (carbs, water regulator, updated RAVES, etc) and I guess digging into electrical is next