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  #1  
Old 07-15-2020, 11:39 AM
gusco's Avatar
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Default Got a Doozy

I'm going nuts and have 2 other experienced techs trying to help me out on this one... Can't seem to get any where. So maybe a few more set of heads put together can help me figure this one out:
2008 Suzuki RMZ450. Came in with a no start, had sat a while.
Checked valve clearances, adjusted, still no start.
Did a leak down test: 90% leak, most notably from the intake valves.
Put in new pro-x stainless steel valves and a pro-x piston while I was in there.
Pulling it apart, I found two broken electrical connections: the air temp sensor and the fuel pump (had been previously repaired/soldered) connector broke loose right at the pump (leaving no chance for a decent repair).
Before ordering the expensive pump, I figured I'd assemble and see if it sputtered. Put it all together (have checked timing 4-5 times now), leak down test shows under 10% loss now (needle has consistently settled between 3-10), it has spark, but I cant get it to sputter on starter fluid.
Any ideas???
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Old 07-15-2020, 05:32 PM
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Fuel pump may need to be primed to get it to fire? Maybe the ECU isn't firing the plug if the fuel pump isn't primed or running.
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Old 07-16-2020, 06:03 AM
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Put a timing light on it while you are cranking it and see if it is firing.
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Old 07-16-2020, 01:44 PM
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Thanks for the ideas! Fuel pump (and tank) are off the bike. I'm trying to get a sputter using starter fluid before ordering the almost $400 fuel pump. It does have a spark. I can see it clearly when I ground the plug and kick it over.
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Old 07-16-2020, 01:58 PM
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Maybe try it with the pump plugged in, electronics can be "real fun" to troubleshoot.
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Old 07-16-2020, 03:05 PM
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That's next on my things to try! The fuel pump plug broke off right at the connection at the base of the tank. I'm going to try to feed it 12v to see if it's just getting a bad a/f mixture and maybe it'll be closer to right with the fuel pump/injector doing the job.
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Old 07-16-2020, 09:38 PM
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Ran the fuel pump off a battery and tried starting. No luck. Rechecked for spark and I DO NOT have spark again. It is intermittent and weak when it is there... I'm getting ready to insure this bike and just drop a match in the tank...
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Old 07-20-2020, 08:13 AM
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I hate electrical issues, they are the least fun to troubleshoot for me. Bad stator or CDI perhaps?
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Old 07-20-2020, 08:29 AM
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It might be. Electrical is my achille's heel... I hate doing electrical work! As I continue testing, I am more certain what I have is an intermittent spark. I have spark sometimes, but not others. I'm trying to get a borrowed ignition coil to rule that out because one of my meters is reading no resistance across the primary, but my second meter is reading on the lower end of good (.17-.70 is good, according to the manual, and the second meter reads right on the lower end of that).
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Old 07-21-2020, 07:48 PM
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Borrowed an ignition coil just to see what would happen: same result. Borrowed a peak voltage adapter: everything (except peak voltage at the coil, still pending getting some needle probes) tested fine as well. Im going to test the harness and if that's not it, then it may be the CDI.
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