I have cleaned carbs, replaced plugs, changed gap on plugs up and down, new coil, repaired exhaust (freeze plug), replaced fuel lines, cleaned raves, compression is at 150 on both cylinders. Not sure where to go next. Starts easy, carbs are set to factory specs. Have not adjusted raves or done any work on water regulator.
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Cant reach max rpm's
- Thread starter Cornnutt
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My problem solved!
OK I fixed mine! I went out this morning and adjusted all the valves (engine and water box) all the way in. Took it out and there was no change. So I switched it to the "reserve" position on the fuel selector , even though I had a full tank of gas, and it ran normally. I switched back to "ON" and it wouldn't run above 5-6K again. Back to "reserve" and everything was great. Apparentely I have a partial obstruction of the regular fuel line or pickup. I'll have to research how to fix that but I'm glad it's running normally again. Hope this helps others!
OK I fixed mine! I went out this morning and adjusted all the valves (engine and water box) all the way in. Took it out and there was no change. So I switched it to the "reserve" position on the fuel selector , even though I had a full tank of gas, and it ran normally. I switched back to "ON" and it wouldn't run above 5-6K again. Back to "reserve" and everything was great. Apparentely I have a partial obstruction of the regular fuel line or pickup. I'll have to research how to fix that but I'm glad it's running normally again. Hope this helps others!
I really don't think the RAVE valve adjustment made the difference in mine. I think mine was the fuel pickup problem. If you search for these symptoms there are lots of posts referring to fuel delivery problems.
foulmouthfool
New Member
you sure they didn't grind your rave valves down too much?
I had the same problem after cleaning and replacing some rave valve parts. I don't know if I had the wrong cap (not the actual cap, the "piston exhaust" that screws onto the stem) that allowed the valve stem to screw too far in, so if I screw it all the way down it pulls the rave valve into the open position. It made that one side stuck open. I had to unscrew the stem in the cap until I got as much play in that side as I had on the other one (eyeballed it). I have some new parts on the way so I won't have to keep it ghetto fixed.
I had the same problem after cleaning and replacing some rave valve parts. I don't know if I had the wrong cap (not the actual cap, the "piston exhaust" that screws onto the stem) that allowed the valve stem to screw too far in, so if I screw it all the way down it pulls the rave valve into the open position. It made that one side stuck open. I had to unscrew the stem in the cap until I got as much play in that side as I had on the other one (eyeballed it). I have some new parts on the way so I won't have to keep it ghetto fixed.
Boater454 thats awesome you figured yours out. Finally a small ray of light. When yours wasn't running correctly could you ever get it to rev past 5K? I'm hoping maybe mine will be close to the same as yours. I repalaced all my gray lines and the fuel selector switch, but haven't done anything inside the tank. I've tried running in res and it didn't help, but maybe both of my lines in the tank are messed up. Crossing fingers. Seriously thinking about skipping the wedding to try this weekend dont think I can wait 2 weeks to try it.
BigPerm I hope that does fix your problem definitely couldn't hurt. Let me know if you need the pages from the manuel on the water regulator I can email them to you.
BigPerm I hope that does fix your problem definitely couldn't hurt. Let me know if you need the pages from the manuel on the water regulator I can email them to you.
bigJake
Well-Known Member
You'll have to research the specifics but I'm pretty sure turning both the RAVES and the water Regulator valve all the way in is wrong. They are typically set opposite of one and other.
bigJake
Well-Known Member
The washers were probably factory installed. They test and adjust spring tension at the factory. one of my skis also had washers in the water regulator
russssellcrow
New Member
I GOT THE SAME BUG YESTERDAY. Finally got my 97 Challenger 787 out on the water, it revs to 5K and just stays there for about 30 seconds, then something mysterious occurs, and it suddenly TUNES UP AND FLIES. Tried feathering the throttle between 3/4 and FULL--has ZERO EFFECT. But when it decides to go, suddenly the sound pitch changes from a 5K grumble to that sweet high pitched whine and the power doubles.
What Dr. Honda says makes a lot of sense. By injecting water vapor into the header, it changes the velocity of sound (sound travels much faster in water than in air--see Tsunami Theory) and thus the reflective compression wavelength of the header. This effectively tunes the header to the RPM of the engine. If the water valve is wrong and there is too much steam constantly entering the header, the compression wave returns while the cylinder exhaust port is still open, and prevents the fresh fuel air from entering the cylinder correctly (scavenging)--thus it bottlenecks and kills the power. I would guess that simulating this on dry land can't be done. If the jet pump is not loading the engine, the RPMs would cross the 5K barrier with no worries (much like jumping a wake, the engine unloads and is instantly able to max RPMs).
Great Discussion!
I will experiment with the Water Valve tuning and try to bring back some data. Good luck all.
What Dr. Honda says makes a lot of sense. By injecting water vapor into the header, it changes the velocity of sound (sound travels much faster in water than in air--see Tsunami Theory) and thus the reflective compression wavelength of the header. This effectively tunes the header to the RPM of the engine. If the water valve is wrong and there is too much steam constantly entering the header, the compression wave returns while the cylinder exhaust port is still open, and prevents the fresh fuel air from entering the cylinder correctly (scavenging)--thus it bottlenecks and kills the power. I would guess that simulating this on dry land can't be done. If the jet pump is not loading the engine, the RPMs would cross the 5K barrier with no worries (much like jumping a wake, the engine unloads and is instantly able to max RPMs).
Great Discussion!
I will experiment with the Water Valve tuning and try to bring back some data. Good luck all.
Connutt I received amnew spring and tried it with no luck. Adjusted RAVES all in and all out with a change. GSX would not plain out at all. Have a new to me water reg coming from Minnetonka!!!! I will see if it works.
Russssell that makes since. Let us know us know how it works.
Russssell that makes since. Let us know us know how it works.
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That suck bigperm I was hoping the new spring would solve your problem. Have you been inside your tank? I think this weekend I'm going to buy a long length of fuel line and go straight from the carb inlet into the tank. Just fish it in there somehow and eliminate everything else. See if that works I'm crossing fingers.
Ok weekend update. I filled the gas tank to half then took the big hose that you poor the gas in with off. Ran a line from the Y into the carbs back into the hole the big hose hooked up to. Eliminating all things inbetween the tank and carbs. Ran the exact same no chage :-(. Bigperm let me know if your new reg works and where did you get it. I might try a new one. Just hate to spend $200 on a guess, but at this point I'll try anything.
After I removed the gray lines I rebuilt both carbs new kits/filters. The fuel system should be squeaky clean now. One local person who claims to know about jetskis told be to put a small restriction in the return line. Has anyone heard of this? Was there maybe one with the gray lines that I removed without knowing?
Thank you for all the ideas keep them coming I really appreciate them. I think my next step is to bite the bullet and fork out the cash for a new water regulator to try. Anyone know where to get a good deal on one? I don't want to buy a used one. I want a brand new one so if it doesn't fix my problem I atleast know for sure its not that.
Thank you for all the ideas keep them coming I really appreciate them. I think my next step is to bite the bullet and fork out the cash for a new water regulator to try. Anyone know where to get a good deal on one? I don't want to buy a used one. I want a brand new one so if it doesn't fix my problem I atleast know for sure its not that.
russssellcrow
New Member
Took the Challenger out twice this weekend and tried several variations of the Water Valve (from completely closed to 2 turns above point where red adjustor is flush with black valve body--in increments of 1/2 turn). This had NO EFFECT. I checked to make certain valve diaphram was good and moves easily, spring is undamaged, but the 3 washers are not present at the base. ALSO, noticed the brass insert to the purple muffler chamber IS BENT. My next path is to disassemble and get a straight brass insert, could this be binding even though diamphram moves smothly up and down?
Also, set water valve to flush with body plus 2 notches open, and tuned on Rave Valves. Got a little better performance with Raves open about 1/2 turn. Then wnet back to tuning water valve, again--NO EFFECT.
Still, from a dead stop, engine revs easily to 5000 RPM, then stays at this speed until the hull planes out, then after a completely variable delay (can be 5-60 sec.) the engine miraculously WINDS UP INSTANTLY to 7000 RPM and the boat takes off like a shot.
Question for the Experienced: Is there a 2nd Rev Limiter built into this MPEM at 5K? My Speedo Sensor is dead, if this MPEM thinks the boat is stopped in the water, will it prevent the spark from advancing the RPM? (to prevent cavitation of the jet pump).
Also, set water valve to flush with body plus 2 notches open, and tuned on Rave Valves. Got a little better performance with Raves open about 1/2 turn. Then wnet back to tuning water valve, again--NO EFFECT.
Still, from a dead stop, engine revs easily to 5000 RPM, then stays at this speed until the hull planes out, then after a completely variable delay (can be 5-60 sec.) the engine miraculously WINDS UP INSTANTLY to 7000 RPM and the boat takes off like a shot.
Question for the Experienced: Is there a 2nd Rev Limiter built into this MPEM at 5K? My Speedo Sensor is dead, if this MPEM thinks the boat is stopped in the water, will it prevent the spark from advancing the RPM? (to prevent cavitation of the jet pump).
Cornnutt I purchased my regulator from MInnetonka on here. A great guy to deal with he probably has more.
Now for my Sunday ride. New reg adjusted flush. New plugs gaped at .024. RAVES flush. GSX pulls hard to 5500 and stops. Impeller out of water 7000 and runs for 30 to 45 seconds. Back to 5000. Check plugs and they are a little lean not too bad. Adjust Reg 3 clicks out and RAVES 3 clicks out goes to 5700 until impeller comes out and then takes off to 7000. Low side of carbs are at stock setting and hs is all the way in. It did run a top speed of 54 MPH yesterday, Carrying a 290lb load!!! So I am getting close. I was wondering about the rev limiter too. It seems as if it might be electrical.
Now for my Sunday ride. New reg adjusted flush. New plugs gaped at .024. RAVES flush. GSX pulls hard to 5500 and stops. Impeller out of water 7000 and runs for 30 to 45 seconds. Back to 5000. Check plugs and they are a little lean not too bad. Adjust Reg 3 clicks out and RAVES 3 clicks out goes to 5700 until impeller comes out and then takes off to 7000. Low side of carbs are at stock setting and hs is all the way in. It did run a top speed of 54 MPH yesterday, Carrying a 290lb load!!! So I am getting close. I was wondering about the rev limiter too. It seems as if it might be electrical.
russssellcrow
New Member
Cornnutt, I'm getting pretty frustrated too, but I have an infinite capacity for futility.
It's a good question, if the 5K RPM problem is electrical, what would it have to do with jumping a wake...
Truth to tell, since nobody chimed-in with a gotcha regarding "the Speedo must work to enable a spark advance above 5000 RPM", I'm assuming it is not a "feature" of Seadoos. Of course, I rebuilt and rechecked my carbs 3 times before I got the engine to top 3000 RPM by merely putting the shifter to FORWARD (what an ugly little discovery).
Honestly, my last test runs seemed to indicate that the engine bolted from 5K to 7K sooner when I was running down wind. The engine never hit 7K before the boat was planed out. Once it planed out, I could easily run the throttle from 7000 to 4500 and back to 7000 RPM as long as I didn't let the speed drop the hull back below planing speed (appr. 15 MPH). Perhaps it is a mid-range torque problem after all.
I got a new Speed Sensor today, and I plan to do a thorough workup on the Water Valve at the same time. Patience is growing shorter.
:willy_nilly:
It's a good question, if the 5K RPM problem is electrical, what would it have to do with jumping a wake...
Truth to tell, since nobody chimed-in with a gotcha regarding "the Speedo must work to enable a spark advance above 5000 RPM", I'm assuming it is not a "feature" of Seadoos. Of course, I rebuilt and rechecked my carbs 3 times before I got the engine to top 3000 RPM by merely putting the shifter to FORWARD (what an ugly little discovery).
Honestly, my last test runs seemed to indicate that the engine bolted from 5K to 7K sooner when I was running down wind. The engine never hit 7K before the boat was planed out. Once it planed out, I could easily run the throttle from 7000 to 4500 and back to 7000 RPM as long as I didn't let the speed drop the hull back below planing speed (appr. 15 MPH). Perhaps it is a mid-range torque problem after all.
I got a new Speed Sensor today, and I plan to do a thorough workup on the Water Valve at the same time. Patience is growing shorter.
:willy_nilly:
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