1996 Yamaha WRA650U, idles fine, but will not rev up.

[Horsenipp]

Hello group, I recently bought a couple of used Waverunners, a 95 WRA700T and a 96 WRA650U. The 650 will fire right up and idles just fine, but it will not rev up. The ski is on a trailer and has a water hose connected. Both cylinders have 125 psi compression, I have confirmed that there is not a fuel starvation issue, I have also confirmed that the spark plugs, ignition coil, wires, and carburetor are all in good working order. I found a diagnostic test online and found that all voltage and resistance readings are all within spec. (See attached) with the exception of the pulser coil, it is supposed to have 4 - 5 VAC, mine only has 3 VAC

Thank you in advance for any assistance that you can offer.

 

[alldodge]

Welcome

The 650 will fire right up and idles just fine, but it will not rev up.

When the throttle is increased, does the cable move the the the throttle body?

 

[Horsenipp]

Yes, of course, I checked all of the basics first... Any other ideas, I'm thinking it might be the rev limiter, so I'm going to replace the CDI box...

 

[alldodge]

Full disclosure never work on a wave runner, seadoo guy here

Don't see it being rev limiter because it idles good and doesn't even start to rev up.

Do wonder with the throttle opening at idle the motor should cough and dies of something.

The TPS is a variable resistor, use a voltmeter and measure pins with key ON motor off. See if the voltage changes as its given more. Or disconnect the connector and use a ohm meter to see if the resistance changes

 

[Horsenipp]

Full disclosure never work on a wave runner, seadoo guy here

Don't see it being rev limiter because it idles good and doesn't even start to rev up.

Do wonder with the throttle opening at idle the motor should cough and dies of something.

The TPS is a variable resistor, use a voltmeter and measure pins with key ON motor off. See if the voltage changes as its given more. Or disconnect the connector and use a ohm meter to see if the resistance changes

Hello, thanks for the reply, but it seems like it tries to rev up, but again, it sounds like it's up against the rev limiter. It's a 1996, it does not have a TPS on it.

 

[alldodge]

Hello, thanks for the reply, but it seems like it tries to rev up, but again, it sounds like it's up against the rev limiter. It's a 1996, it does not have a TPS on it.

TPS Throttle Position Sensor
ok, this is a carberated model?

 

[Horsenipp]

TPS Throttle Position Sensor
ok, this is a carberated model?

Correct, it has a single Mikuni that runs perfectly on a similar ski.

 

[alldodge]

Being a carb and it won't rev I would look at fuel delivery and timing. While some ignition systems have limiters, most carb models do not

Normally a carb will clog up at idle and be even worst at higher rpm, but it might be flooding or main jests are clogged

I might be doing you a dis-service being I'm not knowledgeable of your craft. Have you posted on Green Hulk? Those guys knows the ski's

 

[Horsenipp]

Being a carb and it won't rev I would look at fuel delivery and timing. While some ignition systems have limiters, most carb models do not

Normally a carb will clog up at idle and be even worst at higher rpm, but it might be flooding or main jests are clogged

I might be doing you a dis-service being I'm not knowledgeable of your craft. Have you posted on Green Hulk? Those guys knows the ski's

I really appreciate your input, but you must not have read my original post. You are questioning things that i have already addressed. Thanks, I'll run it by them.

 

[alldodge]

Good luck Sir

 

[cyclops222]

Stuck float ? Incorrect float height ?

 

[Horsenipp]

Stuck float ? Incorrect float height ?

To all:
PLEASE read my initial post before you reply, I have been very specific about what I have checked so far, including the results.
I really appreciate everyone that has tried to help me.

 

[Horsenipp]

I read that it might not be revving up because it's out of the water and on a trailer, is that possible ? It might be up against the rev limiter, to protect the engine, thinking it jumped a wave, or ?