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Discussion Starter · #1 ·
I have a 2001 Kawasaki Prairie 300 that will idle, but dies when you give it throttle. If i give it throttle very slowly, it will rev up and run good, but will not run with fast advance of throttle from idle. Been through carb several times and even put different carb on it. No help. Never had problems until Kawasaki dealer installed new wiring harness. I did notice that there is no power to the sensor and heater wires that attach to bottom of carb. Would this cause my problem? I have blown out all fuel lines, new gas, etc. etc., adjusted air mixture screw, but nothing has helped. Please help if you have any ideas.
 

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Your ability to creep the engine speed up and hold it, yet it dies if cracked open from idle, is an indication that the tube above the main jet and main jet needle holder are dirty.

You need to remove the main jet, pull the tube and the needle holder and then check all the small holes in the side of the tube. My bet is that they are full of white corrosion from the use of automotive pump gas and letting it set for a while.

Most people remove the sensor and heater from the carburetor and rejet it to run properly. So, I really doubt that is the problem.
 

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Discussion Starter · #3 ·
The main jet and needle holder were pulled when going through the carb. All wholes in the tube are clear. To eliminate the carb, i pulled the carb off of a buddy's 300 and it still did the same thing. Is there anything else it could be, other than carb?
 

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The fuel supply from the petcock may be blocked. On the 300 there are also small screens in the fuel tank that act as fuel filters. They can plug.

One thing you may want to try is to slowly bring the engine up to operating speed and try it under load. If it conks out, then I would look at the grounds for the battery and the Igniter.

If someone were to crank on the engine with the spark plug removed and the spark plug wire not grounded, or parts of the wiring harness disconnected; it could have blown the coil or destroyed the Igniter to the point that you no longer have enough spark to handle a full fuel mixture.

Both the coil and Igniter can be easily checked by the dealer if you do not have the service manual and a good digital multimeter.
 

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Discussion Starter · #5 ·
Tank, hoses, everything fuel related has been gone through several times because I intially felt it had to be fuel or carb issue, but all is good there. When it is rev'd up under load it runs fine. Once I creep up to speed and rpms, it stays running great. Dealer installed new ignitor, CDI and evrything when they replaced the harness. Maybe something already went bad that they installed? Dealer basically no help any longer, after $1100 worth of payments I might add. Thanks for the advice, i really appreciate it. Maybe i'll try another dealer. Completely at a loss with this one.
 

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Do you have the equipment to do a vacuum test on the vacuum valve diaphragm? If they develop cracks from fuel contamination or old age, the diaphragm will be slow to respond.

If the main jet needle is not connected to the correct side of the spring retainer this same symptom can occur.

There is also a starter jet that if it gets plugged or lost will cause a venturi vacuum reduction and makes them a nightmare to find the trouble with bogging.

Same thing will happen if the pilot air screw is missing one of its seals or is not properly adjusted. They lean out and conk out before they can build enough rpm to get up to power on a snapped open throttle.

I would print off the carburetor parts diagram from Kawasaki.com and fully disassemble the carburetor and double check all jets and seals.

Set the pilot air screw three turns out from lightly bottomed, and see if that makes a difference. If so, then search my posts for the procedure on how to adjust the pilot air screw for the best performance and economy. Easy to do, just time consuming to do it right.
 

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Discussion Starter · #7 ·
Well, the diaphram was replaced with a new one last week. The starter jet is clear and clean as well as the pilot jet. The main jet needle is seated correctly and went through the carb form start to finish. Still don't think it is the carb due to puting on a good running carb off of another machine and had same symptoms. I have pretty much eliminated the carb. I don't have a way to test the coil and ignitor so it looks like I have no choice but take it back to a different dealer to try and figure out what my problem is. Thank you RCW for your help. I am now confident it is not in the carb at least.
 

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go through and make sure all the connections are tight and clean at the cdi battery etc.also check your fuses to see if any have blown or not seated in all the way.also have you adjusted the air mix screw and if so has it helped or made it worse or no change?may want to make sure the choke is workin ok and the plug gap is good and the plug it self is good with a crisp blue spark. that is prolly where id start if the carb is clean is check the spark color and go out from there.go back to basics,fuel --- spark--- air---compression,
may also want to check the valve lash and do a comp test to make sure all is good there.
 

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After having the exact same problem with my 2001 Prairie and 2 years of not using it because it ran like crap ironically after it was tuned up and the carburetor rebuilt. I finally took it to another dealer and they fixed it! Mechanic said it was a common problem when rebuilding the carburetor to misplace and lose a jet that is not screwed in. On the Kawasaki Carburetor Parts Diagram it is part #16017. My Prairie runs like New!!
 

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A couple random thoughts on this subject. Bear with me cause I can get long winded.

First, I've seen (and have done it myself) the main and starter (choke) jet swapped. Meaning it'll run pig rich with the choke on, and lean (BAD LEAN!) with no choke, throttle it up slowly and it'll kind of accelerate but not really. Hammer it, and dies immediately. The 2 jets are identical on the outside, however, the orifice is dramatically different. IIRC, the main jet should have a "134" or something similar marked on it, and the starter (choke) jet should be something like 85. Big difference. Obviously the main jet should be the larger of the two. Sounds like that's not going to be an issue if the carb was removed from a known-good-running Prairie.

Also I've seen sometimes where the bowl vent tube can get pinched. I look at all of them if I've got the tank off and about 50% of them are pinched. The carburetor depends on atmospheric pressure to force fuel from the bowl up through the jet (that's how it works...the differential in pressure between atmospheric and the venturi). If the vent tube is pinched and/or clogged (also common), they idle fine and kind of accelerate up to a certain point, but once past about 1/4 throttle-or if you just hammer the throttle-it'll die.

Finally electrical systems. Kawasaki 300's (and some of the 400's) have a "total loss" ignition system. In a nutshell, the CDI depends heavily on battery voltage. If it's lower than about 11 volts, they run like poo. If it's over about 14.5 volts, they'll run like poo. And I've seen them both ways. USUALLY if it's a low voltage problem, they'll idle ok but if you accelerate slowly, they'll run-up to a certain RPM-then start to sound like they have a limiter and just won't accelerate any more. About 3500 RPM roughly as my memory serves me. If you turn the headlights on, sometimes it'll get another 300-500 RPM. Then if you just hammer the throttle, most times they'll just quit when the engine reaches about 4000 RPM, give or take a thousand or so (there is no real set RPM at which they want to die, each one seems to be different). Running with a dead battery, or NO battery, will both show same symptoms. THEN---we get into overcharging, which is not uncommon with 300's. Same type deal. Engine will run ok up to about 6000 RPM, or thereabouts, then it wants to fall on it's face. Depends on the amount of overvoltage. I've seen some that'll charge 40 volts and BOIL batteries (and melt wires)...they run like absolute garbage. Most of the time it's just about 15-16 volts at the battery with the engine running, they'll also cause running problems. Look at the regulator, the pins on the reg itself as well as the harness. If the wires are burnt, fix it, then check the regulator/rectifier's charge voltage at the battery. If over 14.5-14.8, replace it.

300's are kind of fickle in certain ways, however, most of the time when I get one that wants to throw me a curve, I end up kicking myself for not figuring it out sooner. Usually it's a simple fix and honestly has to be since the 300 is not real complicated.

OH one other issue I've run into. The duct that runs up the left side of the ATV, from the air box to the front, has several connections. One of the larger connections has been known to come off at one point or another, and the engine then becomes gutless (lean). Most of the time they'll take up to about 1/4 throttle but beyond that and the engine wants to die. Same thing happens if the crankcase vent hose is not installed onto the duct, though, to a lesser extent. If the vent hose is off, they'll accelerate ok even up to full throttle, but they just feel a little low powered, and normally if it's been off a while, there's dust/oil around where the hose is laying as the oil vapors collect dust/dirt. OH and forgot to ask, you are attempting to diagnose running problems with the airbox lid ON, right? (if it's off, you'll chase your tail for a long time...they exhibit same problem with the lid off as it does with the duct being off)...

Just some rambling, and I hope that gives you at least some ideas.
 
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