My GTX starts fine and runs fine until I go to wide open throttle and then it acts like it's running out of fuel. It will drop down in RPMs and speed for about 2-3 seconds the take off to full speed then drop off again a few seconds later. I installed new spark plugs, checked and cleaned the fuel filter, pulled the fuel pick up out of the tank looking for a possible clog in the pick up tube,its clear and ran it empty and added fresh fuel,but problem still exist.Over the winter I add an additive to the fuel to keep the Ethenal from seperating and jelling up in the tank,but it fine for serveral tanks of gas before this problem cropped up. Any Ideas?
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1996 GTX Something is wrong!
- Thread starter RoRo
- Start date
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Hey RoRo, welcome to the forum.
You've gotten a good start to fixing it, but I do have a few questions. Did you read the plugs before you threw them out by chance? Is it only at full throttle? Can you get to higher RPMs at partial throttle w/o problem? Has the carb ever been rebuilt? Are you still using oil injection or running premix?
You've gotten a good start to fixing it, but I do have a few questions. Did you read the plugs before you threw them out by chance? Is it only at full throttle? Can you get to higher RPMs at partial throttle w/o problem? Has the carb ever been rebuilt? Are you still using oil injection or running premix?
The plugs I removed looked great,clean burning but I changed them anyway to rule them out as the problem. The problem only ocurrs at 4800+ rpms in the water and 6800+ rpms out of the water ,even if I ease into it.. I have never had the carbs rebuilt and I still run synthetic injector oil.I thought maybe it was REV. Limiter but I can rev it to a higher rem out of the water before acts up.I also removed the RAVE valves and cleaned the carbon build up and checked for damage to the diaphams,all look OK!
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If you search other forums, you will find a large community of people complaining about fuel realted problems for boats of this generation.
My 1996 HX is up for a carb rebuild and fuel hose replacement for similar performance problems you described. The 1996 GSX I have been resurrecting for a friend had already had the hoses replaced at some point.
My 1996 HX is up for a carb rebuild and fuel hose replacement for similar performance problems you described. The 1996 GSX I have been resurrecting for a friend had already had the hoses replaced at some point.
chariotdriver
New Member
RAVE's
If it is running great for a few minutes and starts acting up when it warms up---I'm betting you have the original bellows on your RAVE's and one or both are a little stretched out. I replied to a similiar post after I figured out my similiar problem a few days ago. Hope this helps, cd
If it is running great for a few minutes and starts acting up when it warms up---I'm betting you have the original bellows on your RAVE's and one or both are a little stretched out. I replied to a similiar post after I figured out my similiar problem a few days ago. Hope this helps, cd
I,ve checked the Rave bellows for holes and cracks and they looked good,but I didn't know they could be stretched! How can I tell if they are stretched they both look the same.
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chariotdriver
New Member
RAVE's
The 787 motor's don't use any restraint on the bottom part of the bellow like the 951's do. Somebody on another post has very good pictures of this. I used some very small ty-rap's on the bottom of the bellow and of course the top has the stock spring. Make sure you clean everything up real good; a worn wire brush on a bench grinder works good to get the carbon build up off----just don't get carried away. Good luck
The 787 motor's don't use any restraint on the bottom part of the bellow like the 951's do. Somebody on another post has very good pictures of this. I used some very small ty-rap's on the bottom of the bellow and of course the top has the stock spring. Make sure you clean everything up real good; a worn wire brush on a bench grinder works good to get the carbon build up off----just don't get carried away. Good luck
Carb trouble!
Although the idea of a RAVE valve problem sounds a bit logical, there is one part that doesn't. If the bellows have no holes in them and are still pliable, then it really shouldn't matter about them being stretched a bit. Reason being is because the Rave valves, which are normally in their lowest postion to the cylinder at low speed, are kept this way with spring tension. You'll note the spring in the RAVE valve really doesn't have that much tension on it to close them during low RPM's. When you increase your throttle, you increase pressure on your cylinder. The RAVE valve has an internal port, that uses that pressure to push the valve open as you increase your speed. If there was a bit of stretching, or even a small hole, it shouldn't really keep the engine from running at top speed. The rave valve allows the engine to exhaust more gases from the engine so you can breath more fuel, hence making high rpms.....this was an engineering marvel. If the valve is sticking, it will run crappy at low rpm's, but once you pass a certain speed, the engine will kick in and go wide open. Just make sure your red caps on top are tightened all the way down.
I think your having a carburetor problem. On the 787 (which is my personal engine type) the two carbs are sycronized to each other, one called a MAG, the other called the PTO. This really means that one is on the magneto side and the other on the pto side of the engine. The carbs operate in three ranges and controlled as follows:....Low speed screw, for idle to slow speeds,........the Pilot Jet, which is for your in between speeds and last, the Main Jet....so if your engine seems to be going back into the hole and when you come out of it it's fine, I would think you have partial plugging in your main jet of either one or both of your carbs. I'd recommend taking them down, one at a time, and go through them. You don't have to buy a carb rebuild kit right away, I'd just look at them, carefully removing and looking into the jets and diaphragms. You can use carb cleaner and that little nozzle that comes with it to spray through the holes to make sure the internal ports are clear. Check the diaphragms for holes etc... Carb gaskets can normally be reused as long as they weren't sealed with a sealant. I'd only do this long enough to trouble shoot. If you find the problem and fix it, then come back within a riding season to replace those gaskets, because you dont' want one sucking air, that's another story.
If you do take them off, one at a time, pop off your syncro bar, that connects the two carbs together, from the pto side and careful not to disturd that setting. If you make any changes to these cables, one is your throttle and the other to your oil injection pump, you must make sure you re-check the settings from the oil pump. That is very important. You don't want to move it because you could make the engine burn to much oil and cause plug fouling and carbon build up, or to little and burn the engine up.
I hope this helps!.........but I am 95% sure it's either one or both of your carbs........
Although the idea of a RAVE valve problem sounds a bit logical, there is one part that doesn't. If the bellows have no holes in them and are still pliable, then it really shouldn't matter about them being stretched a bit. Reason being is because the Rave valves, which are normally in their lowest postion to the cylinder at low speed, are kept this way with spring tension. You'll note the spring in the RAVE valve really doesn't have that much tension on it to close them during low RPM's. When you increase your throttle, you increase pressure on your cylinder. The RAVE valve has an internal port, that uses that pressure to push the valve open as you increase your speed. If there was a bit of stretching, or even a small hole, it shouldn't really keep the engine from running at top speed. The rave valve allows the engine to exhaust more gases from the engine so you can breath more fuel, hence making high rpms.....this was an engineering marvel. If the valve is sticking, it will run crappy at low rpm's, but once you pass a certain speed, the engine will kick in and go wide open. Just make sure your red caps on top are tightened all the way down.
I think your having a carburetor problem. On the 787 (which is my personal engine type) the two carbs are sycronized to each other, one called a MAG, the other called the PTO. This really means that one is on the magneto side and the other on the pto side of the engine. The carbs operate in three ranges and controlled as follows:....Low speed screw, for idle to slow speeds,........the Pilot Jet, which is for your in between speeds and last, the Main Jet....so if your engine seems to be going back into the hole and when you come out of it it's fine, I would think you have partial plugging in your main jet of either one or both of your carbs. I'd recommend taking them down, one at a time, and go through them. You don't have to buy a carb rebuild kit right away, I'd just look at them, carefully removing and looking into the jets and diaphragms. You can use carb cleaner and that little nozzle that comes with it to spray through the holes to make sure the internal ports are clear. Check the diaphragms for holes etc... Carb gaskets can normally be reused as long as they weren't sealed with a sealant. I'd only do this long enough to trouble shoot. If you find the problem and fix it, then come back within a riding season to replace those gaskets, because you dont' want one sucking air, that's another story.
If you do take them off, one at a time, pop off your syncro bar, that connects the two carbs together, from the pto side and careful not to disturd that setting. If you make any changes to these cables, one is your throttle and the other to your oil injection pump, you must make sure you re-check the settings from the oil pump. That is very important. You don't want to move it because you could make the engine burn to much oil and cause plug fouling and carbon build up, or to little and burn the engine up.
I hope this helps!.........but I am 95% sure it's either one or both of your carbs........
All hoses. No point in leaving any section of the original hose if there is evidence of deterioration. Remember that you want reliability from the fuel system following a carb rebuild.
But if you absolutely must do the bare minimum, at least the hoses between the fuel tank and selector valve and carbs.
chariotdriver
New Member
RAVE Bellows
The part of the bellow which was stretched on my ski was the bottom part which grips the housing. It was actually pushed up and partly off the housing causing quite a mess and would not build up enough pressure to move the RAVE up to its open position. It would get the RAVE to move up for short bursts but would always drop back down about 1500 RPM. I grabbed a few paragraphs off of the Sea-Doo racing manual CD, I haven't figured out how to get the Adobe pictures posted as they are quite informative.
The following is a cut & paste from the manual: hope this helps
The RAVE valve does not allow an engine to make
higher peak horsepower than an engine not so
equipped, it can however make moving the peak
horsepower higher practical, because of its effect
on the rest of the power curve. Item 2 in the following
figure is the power curve of an engine with
the RAVE valve held fully open through its entire
RPM range. Item 6 notes the peak power produced.
That peak will not change if the exhaust
port time of a similar engine without a RAVE valve
was the same (with all other features equal).
Item 1 is the power curve of the engine with the
RAVE valve closed through its entire RPM range.
The shaded area (item 3) is the improvement in
power at lower engine speeds that is gained because
of the lower exhaust port. If the port remains
at this height however, the power would
peak as noted in item 5. Raising the exhaust port
at the proper RPM (item 7) will allow the engine
peak power to continue to rise (item 6).
Item P1 in the figure is the force of the return
spring against the diaphragm. The exhaust pressure
must be high enough to overcome this force
before the valve begins opening. Item P2 is the
pressure required to completely open the RAVE
valve. Between P1 and P2, the usable power
curve of the engine is moving from curve 1 to
power curve 2. This transition takes place very
rapidly at full throttle and from a practical standpoint
can be considered to be instantaneous at
item 7. Gradual application of the throttle, however,
will result in the RAVE valve opening much later.
If the RAVE valve opens toos late, the engine will
bog or hesitate momentarily as the RPM increases.
Full peak performance (item 6) is still available.
From a functional point of view. It is better to have
the valve open a bit early than a bit late.
Rave Valve Adjustment
To adjust the RAVE valve turn the red adjustment
knob all the way in (clockwise). Open the red knob
1 turn out (counterclockwise) and perform an acceleration
run on the craft starting from zero and
accelerating to full speed. Repeat the procedure
until you attain the best performance. The use of
a radar gun with acceleration recording capabilities
is advised in order to obtain accurate data,
however rider observation will surface.
Maintenance
The RAVE components should be periodically
checked. The RAVE valve requires cleaning of carbon
deposits. Cleaning intervals would depend
upon the user’s riding style and the quality of the
oil used. Using FORMULA XP-S synthetic injection
oil, clean the valve periodically. Check for
clean passages between the exhaust port and diaphragm
chamber. If cleaning is necessary, use
solvent to remove the deposits. Also check the
diaphragm for punctures, replace if damaged.
No special solvents or cleaners are required when
cleaning the valve.
The part of the bellow which was stretched on my ski was the bottom part which grips the housing. It was actually pushed up and partly off the housing causing quite a mess and would not build up enough pressure to move the RAVE up to its open position. It would get the RAVE to move up for short bursts but would always drop back down about 1500 RPM. I grabbed a few paragraphs off of the Sea-Doo racing manual CD, I haven't figured out how to get the Adobe pictures posted as they are quite informative.
The following is a cut & paste from the manual: hope this helps
The RAVE valve does not allow an engine to make
higher peak horsepower than an engine not so
equipped, it can however make moving the peak
horsepower higher practical, because of its effect
on the rest of the power curve. Item 2 in the following
figure is the power curve of an engine with
the RAVE valve held fully open through its entire
RPM range. Item 6 notes the peak power produced.
That peak will not change if the exhaust
port time of a similar engine without a RAVE valve
was the same (with all other features equal).
Item 1 is the power curve of the engine with the
RAVE valve closed through its entire RPM range.
The shaded area (item 3) is the improvement in
power at lower engine speeds that is gained because
of the lower exhaust port. If the port remains
at this height however, the power would
peak as noted in item 5. Raising the exhaust port
at the proper RPM (item 7) will allow the engine
peak power to continue to rise (item 6).
Item P1 in the figure is the force of the return
spring against the diaphragm. The exhaust pressure
must be high enough to overcome this force
before the valve begins opening. Item P2 is the
pressure required to completely open the RAVE
valve. Between P1 and P2, the usable power
curve of the engine is moving from curve 1 to
power curve 2. This transition takes place very
rapidly at full throttle and from a practical standpoint
can be considered to be instantaneous at
item 7. Gradual application of the throttle, however,
will result in the RAVE valve opening much later.
If the RAVE valve opens toos late, the engine will
bog or hesitate momentarily as the RPM increases.
Full peak performance (item 6) is still available.
From a functional point of view. It is better to have
the valve open a bit early than a bit late.
Rave Valve Adjustment
To adjust the RAVE valve turn the red adjustment
knob all the way in (clockwise). Open the red knob
1 turn out (counterclockwise) and perform an acceleration
run on the craft starting from zero and
accelerating to full speed. Repeat the procedure
until you attain the best performance. The use of
a radar gun with acceleration recording capabilities
is advised in order to obtain accurate data,
however rider observation will surface.
Maintenance
The RAVE components should be periodically
checked. The RAVE valve requires cleaning of carbon
deposits. Cleaning intervals would depend
upon the user’s riding style and the quality of the
oil used. Using FORMULA XP-S synthetic injection
oil, clean the valve periodically. Check for
clean passages between the exhaust port and diaphragm
chamber. If cleaning is necessary, use
solvent to remove the deposits. Also check the
diaphragm for punctures, replace if damaged.
No special solvents or cleaners are required when
cleaning the valve.
I had the same problem with my 95 GTX. The problem was do to clogged filters inside the carbs. Inside each carb is a small round black filter (about 1/2 inch long and 5 cm in diameter. These can be pulled out easily with a pair of needle nose pliers. These were completely clogged. I flushed them out with carb cleaner, cleaned and reassembled the carbs and problem fixed. With the right tools you can do this job in a couple of hours.
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