94 XP idles but won't rev

[andy.262]

Just got a '94 XP for a decent price, but it has some issues. Engine will start right up no problem and idle for about a second or two. During that second or two if you even think about touching the throttle it will instantly die, won't even try to rev up.

Previous owner said he has done the following work:
- new pistons and rings (checked compression, 150psi both holes)
- carb rebuild
- timed rotary valve
- switched to premix and removed oil pump
- installed new in-line fuel filter

I plan on doing the following:
- rebuild carbs again with "back to OEM" kit from OSD
- replace fuel selector
- replace any remaining grey fuel lines (there are one or two left in there)
- remove in-line fuel filter (because there's not supposed to be one there, right?)
- re-install oil pump (I have a seperate forum thread open for this particular task)

Anything else I should be checking/trying?

I did notice that it does not have that water separator cylinder like my other 2 skis have, but I'm assuming it is supposed to have one?

 

[artr]

If the only grey fuel lines left are on the vent lines for the gas tank I would try the following because it sounds like it only idles for a second or two and then dies even if you don't try to rev it.
Check that the pulse line to the carb is secure on both ends and is not damaged or cracked. You could also connect the fuel line from the carb directly to the fuel tank bypassing the fuel selector and inline filter to see if either are causing a problem. Your ski probably had water separator/filter that should be used instead of an inline filter.

 

[AKnarrowback]

You are on the right track in doing everything you have listed. There are multiple areas of the fuel system that can cause adverse running conditions and ALL must be eliminated to ensure proper running. To do this you have to do a complete fuel system check. Back to OEM is a must, replace the fuel lines, get rid of the extra fuel filter.

Refer to the carb rebuild thread at the top of the two stroke section. Read it, reread it and follow it to a "T". Make sure all passages are cleared out and you have a solid pop off at the proper pressure with no difference between the two. Don't forget to do a fuel system pressurization test to look for air leaks.

Remember however. The fuel systems on the older machines are not "instant response" when the machine is first started, even when the machine is warm. There is a short time where the system is pumping up and everything gets up to operating conditions. This can take ten seconds or more depending on the condition of the machine. It will start and idle just fine, but gassing it too soon can make the motor hiccup or stall out.

Yes on the water seperator that mounts up on the hull above the oil tank. That is an absolute must. One other thing to do is pull your fuel gauge sender assembly out and clear the fuel tank of any built up debris and standing water. The baffle tube doesn't pull the lowest level material out of the tank and after 28 years you might need a good cleaning.

 

[andy.262]

Refer to the carb rebuild thread at the top of the two stroke section. Read it, reread it and follow it to a "T". Make sure all passages are cleared out and you have a solid pop off at the proper pressure with no difference between the two.

Yeah so I recently bought an ultrasonic cleaner. Have you (or anyone else reading this thread) used one to clean carbs before? Any advice on what solutions to use?

My plan is to disassemble the carbs and take out all the rubber/plastic parts and gaskets so that only metal goes into the ultrasonic - is that the correct approach?
Edit: Realized that was a dumb question since I'm replacing all the soft parts with new Mikuni ones anyways. Still would appreciate recommendations for a cleaning solution though

 

[TheGTIjetguy]

I use an ultrasonic cleaner and simple green (or dish soap and warm water) to knock the dirt off the outside of the carb. I’m not convinced that it is a good replacement for carb cleaner and compressed air however.
You can use any available aerosol can marketed as carb cleaner
Inside the carb needs carb cleaner shot through all passages with a can and straw followed by compressed air. Not until you can visually see cleaner flowing out of holes and such can you assume you got everything.
The best cleaning soaks will never get into the nooks and crannies due to trapped air bubbles.

 

[andy.262]

I use an ultrasonic cleaner and simple green (or dish soap and warm water) to knock the dirt off the outside of the carb. I’m not convinced that it is a good replacement for carb cleaner and compressed air however.
You can use any available aerosol can marketed as carb cleaner
Inside the carb needs carb cleaner shot through all passages with a can and straw followed by compressed air. Not until you can visually see cleaner flowing out of holes and such can you assume you got everything.
The best cleaning soaks will never get into the nooks and crannies due to trapped air bubbles.

My experience with the ultrasonic was similar - it does a good job of cleaning the big pieces and little indents and details, but the actual passages still needed to be cleaned out with carb cleaner. I used simple green and 100F water.