07 gsxr750 no prime no spark FRUSTRATED - Suzuki GSX-R Motorcycle Forums Gixxer.com
 
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post #1 of 8 (permalink) Old 07-24-2018, 12:00 AM Thread Starter
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Exclamation 07 gsxr750 no prime no spark FRUSTRATED

morning everyone,
little background, basket case repair for a friend. we would like to get it running first before getting it road worthy (tires sprockets chain brakes et al.)
bike was low sided at speed is my guess, someone has done some sloppy work attempting to get it back together.
bike was "running" when parked several years back
i am fairly handy when it comes to my own bike 00 triumph sprint, 83 honda cb650 sc and the roommates bike 99 intruder (have a certain distrust of that bike) but this is my first nothing works on it bike.

symptoms:
key on, dash on chec message on dash. tried to do the dealer mode jumper wire no change.
bike cranks really well
pulled a plug and a coil, grounded plug and looked for spark while cranking: no spark
key on/off multiple times w/wo kill switch: no fuel prime
key on/off multiple times w/wo kill switch: secondary butterflies dont move (not sure if there supposed to)
key on/off multiple times w/wo kill switch: no horn (not sure where it even is to check for power)

things we have looked at:
all of the fuses in the fuse block look good
replaced fuse on the "main block" ( block with a wire directly off the positive side of the batt)
dicked with the tip sensor (flipped it over and tried it shook it and made sure the ball inside seemed like it was moving)
looked for pinched or otherwise screwed up wiring (found a few things like turn signals that were cut, and a really poorly joined set of plate marker lights).
kick stand switch seems to work (cranks when up but not down)
clutch switch seems to work (clutch in to crank bike)
new fuel in the tank and flushed the tank a few times with fresh fuel.

next steps (that i know about)
check the fuel pump/ FP relay
recheck the fuses again just in case

what am i missing/ what should i check next?

thanks,
Mike
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post #2 of 8 (permalink) Old 07-24-2018, 01:07 AM
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Re: 07 gsxr750 no prime no spark FRUSTRATED

You could have a bad ECU
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post #3 of 8 (permalink) Old 07-24-2018, 04:13 AM
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Re: 07 gsxr750 no prime no spark FRUSTRATED

Since you see CHEC on the dash one or more of the following three things must be happening: 1) Your ECU is bad as Just Nick suggested, 2) Your ECU is good, but is not getting power and 3) Your ECU is online and working but its connection to the dash has been lost. The latter is unlikely both by itself and because you don't have spark, so you need to test which of the first two is the case. Locate your dealer mode coupler and look for an O/W or O/G wire (this depends on model). Turn ignition on and get the bike ready to start (neutral or kikcstand up, engine stop switch set to RUN, etc.) and measure the voltage between that wire and the negative battery pole. If you get nothing you probably have wiring problems, otherwise the ECU might be bad.

Until you get your ECU running, looking for problems having to do with spark or the fuel pump won't help, as the ECU controls all of these subsystems and they're going to remain dead until it does so.
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post #4 of 8 (permalink) Old 07-24-2018, 06:38 AM Thread Starter
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Re: 07 gsxr750 no prime no spark FRUSTRATED

aside from the dealer plug voltage is there a definative way to test the ECU?

thanks guys ill keep you posted.
something tells me that the cost of a new ECU coupled with the other costs is going to put this bike in the junkyard.
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post #5 of 8 (permalink) Old 07-24-2018, 08:08 AM
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Re: 07 gsxr750 no prime no spark FRUSTRATED

Quote:
Originally Posted by piratemike001 View Post
aside from the dealer plug voltage is there a definative way to test the ECU?
If "definitive way" is taken as, some sort of procedure that will tell, beyond the shadow of any doubt, whether the ECU is working properly or not, then only swapping your ECU into a known working bike, or swapping a known working ECU into your bike come to mind.

If various degrees of confidence are acceptable, then you can reason that if the ECU is not getting any power, then its condition is irrelevant. If it's getting power (meaning intact +12V and ground connections) and its connection to the dash is also intact, but it still says CHEC, then a failed ECU is rather likely. (Of course, it might also be the dash that has failed, or something else you've overlooked.)
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post #6 of 8 (permalink) Old 07-24-2018, 10:25 AM Thread Starter
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Re: 07 gsxr750 no prime no spark FRUSTRATED

thats not what i wanted to hear but hey it is what it is... i looked around on ebay, there are plenty of 08-09 computers can i use another years computers on this 07?
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post #7 of 8 (permalink) Old 07-24-2018, 10:37 AM
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Re: 07 gsxr750 no prime no spark FRUSTRATED

Quote:
Originally Posted by piratemike001 View Post
thats not what i wanted to hear but hey it is what it is... i looked around on ebay, there are plenty of 08-09 computers can i use another years computers on this 07?
Only K6-K7 ECU.
Due to K6-K7 charging failures there's is high demand for K6-K7 ECUs. You can use 600 or 750 ECU as long as you flash appropriate bin to it.

In your case it would be wiser to try your bike's ECU on another bike. If there is still some short in wiring harness or some other problem so it won't burn other ECU also.
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post #8 of 8 (permalink) Old 07-25-2018, 02:21 PM Thread Starter
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Re: 07 gsxr750 no prime no spark FRUSTRATED

anyone in the hampton roads area in VA that would like to get together and test my ECU?
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