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Discussion Starter · #1 ·
My Ninja 300 is having problems starting but I recently figured out that if I give it any throttle then try to start it it’ll start right up. I’m not sure what the next move is, I changed the air filter and battery as well. Thanks for the help
 

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What are the symptoms? Does it crank normally but never catch? Do you hear the fuel pump prime when you turn the key and have the kill switch on? Once started, how does it idle?
We're going to need lots more information to have an idea of what to try.
 

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Discussion Starter · #3 ·
What are the symptoms? Does it crank normally but never catch? Do you hear the fuel pump prime when you turn the key and have the kill switch on? Once started, how does it idle?
We're going to need lots more information to have an idea of what to try.
the fuel pump primes and it rides and idles right. when the key is on and the kill switch is on and i try to start it it clicks and buzzes like the same buzz as the fuel pump
 

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the fuel pump primes and it rides and idles right. when the key is on and the kill switch is on and i try to start it it clicks and buzzes like the same buzz as the fuel pump
That's most likely a battery or charging issue.

You need to read the battery voltage before trying to start it. It should be sitting over 12.7V if fully charged. There are other tests, but that's the first.

New batteries are rarely fully charged.
 

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Can you get a voltage read while cranking? A drop is expected, but too much could be an indication of a problem.
Also check the connections at the battery. Loose connections can give these types of symptoms too.
 

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Load testing is the next step. A battery can show full voltage while sitting, but fall way off under load.

Most people say anything under 10V is too low during cranking. Others say 11. If it's way under that there is a bad cell.
 

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how much of a drop, i've read that if it goes below 9 volts is a problem and i will! thank you
I don't know if there's a formal limit, but I've heard around 10V is about as low as you want to see.
Maybe someone with more experience or knowledge knows more.

Where it's a new battery, an excessive drop would lead me to think you've got a problem with the starter or wiring to the starter (but it could just be a faulty battery). Hopefully that's not the case.
It puzzles me that the throttle would have anything to do with it if you're having an electrical problem though. I'm trying to understand the circuit diagram relating to the start circuit, but the jumble of diodes in the Start Circuit Relay has my head spinning (I do mechanical things, not electrical things).
 

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If you have 10 to 11V during cranking, and it's still cranking slowly, the next thing to check would be the voltage at the starter.

If the battery is strong, but the voltage is low at the starter, most of the time it's a bad starter relay.
 

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how do i check the starter voltage?
Did the battery check out ok under load?

If so, locate the positive terminal on the starter, and put the red lead on it. Hold the black lead to a bare metal spot or bolt for a good ground. Have someone hit the starter, read the voltage as it's cranking.

It should be just slightly less than what you get directly at the battery while cranking. If it's way less, there is significant resistance between the two or a poor connection. The starter relay is the most common cause.

Cheap aftermarket relays are usually not very good, and cause more problems. A good used OEM relay is a better bet (if a new OEM one is too expensive).
 

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For information, the Service Manual provides relay box test procedures to check both the start relay and the associated diode circuits. Basically, probe the correct set of pins and check that the resistance is either infinite or low, and then use a battery to juice the relay and make sure the relay closes. If we suspect relay box, I'd recommend the check to confirm before replacing.
I tend to be a "diagnose first" rather than "parts shotgun" type troubleshooter, but that's a personal decision.

Looks like the relay box is over $100 new from OEM, but used ones can be had for around $30 or so.
 

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Absolutely a good idea, after locating what you think is the problem, to do some more specific diagnosis before buying parts.

We've all see threads where the person says - "I've replaced this, that, and the other thing - and I still have the same problem!"
 

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Absolutely a good idea, after locating what you think is the problem, to do some more specific diagnosis before buying parts.

We've all see threads where the person says - "I've replaced this, that, and the other thing - and I still have the same problem!"
I may be more of a nerd than average, but when my Golf Wagon was giving me trouble, I acquired an oscilloscope to monitor sensors until I found the failed unit. The issue only showed up above a certain engine temperature too and mostly on starting warm, so that made chasing it all the more interesting.

Suffice to say, especially if the test is free, I'm going to fully diagnose before spending money on parts, and if I don't have factory test procedures, I'm going to try and make up my own.
 

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Discussion Starter · #16 ·
I may be more of a nerd than average, but when my Golf Wagon was giving me trouble, I acquired an oscilloscope to monitor sensors until I found the failed unit. The issue only showed up above a certain engine temperature too and mostly on starting warm, so that made chasing it all the more interesting.

Suffice to say, especially if the test is free, I'm going to fully diagnose before spending money on parts, and if I don't have factory test procedures, I'm going to try and make up my own.
yes, i like to troubleshoot before buying too so i dont spend too much money
 
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