CBR 600F3 1995 - 1998 CBR 600F3 Forum

98 F3 wont start - just backfires

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  #11  
Old 11-02-2009, 07:41 AM
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You said you got weak spark. you check the voltage on your battery?
 
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Old 11-02-2009, 08:09 AM
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Originally Posted by Kuroshio
You said you got weak spark. you check the voltage on your battery?
battery is fully charged, cranks over quickly. 12V @ the primary's.
ALL 4 seem to be the same, that is why i was thinking that it may be something common, like the pulse generator. the initial spark is quite strong, but after 3 or 4 cranks, it seems to die down, but it still has a spark. i was hoping to borrow a peak voltage adapter from the local dealer, as i know them quite well. the trouble with going to the dealer is that i will be paying them to go over all the things i have already checked.
I am going to drain the carbs to ensure all 4 have fuel, and try it again, but after that, i think it is time to load it up before the snow flies and get to the dealer...
 
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Old 11-02-2009, 08:40 AM
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After a few cranks, especially in succession, voltage will die down. Cranking voltage demand on the battery is huge. Same with leaning on the ignition in a car that won't start. You'll kill the battery.

All this started overnight right? How'd you check for spark? Take each plug out and ground it to the frame? If putting fuel directly in the carbs won't get her to turn over, I'm thinking have fuel in the floats won't matter. It sounds like electrical, not fuel. I'd pull the battery and verify its good at an Autozone or such.
 
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Old 11-02-2009, 09:54 AM
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Originally Posted by Kuroshio
After a few cranks, especially in succession, voltage will die down. Cranking voltage demand on the battery is huge. Same with leaning on the ignition in a car that won't start. You'll kill the battery.

All this started overnight right? How'd you check for spark? Take each plug out and ground it to the frame? If putting fuel directly in the carbs won't get her to turn over, I'm thinking have fuel in the floats won't matter. It sounds like electrical, not fuel. I'd pull the battery and verify its good at an Autozone or such.
first to anwer your previous question, the terminal voltage is 12.8 volts. I used one good plug and grounded it to the frame. all the plugs were new. the battery is good enough that i can get the bike to crank over for about 30 seconds before it starts to slow down. i have also used booster cables connected to a car battery, and still the same thing, just cranks over for alot longer. i think i need to get the peak voltages checked, as i believe that it is electrical as well.
 
  #15  
Old 11-02-2009, 11:19 AM
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Well the longer it cranks without starting the weaker each attempt will get. The battery will recover given a bit to rest. But the demand on the battery when cranking is huge. Since you tried jumping it with a car battery, I'd say that eliminates your battery as a source.

If the plugs plugs are good and gapped correctly, you could be right. I'd double check the fuel flow just to be sure. Oh and make sure the plug wires are in correct order. I know we're always sure but if I hadn't marked mine, I'd have been sure... And wrong
 
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Old 11-02-2009, 11:57 AM
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Did u check the voltage at the coil packs?
 
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Old 11-02-2009, 12:17 PM
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Originally Posted by intiractive
Did u check the voltage at the coil packs?
i checked the initial voltage on the primary side, and it is 12V with the key on, not cranking. i dont have a peak voltage adapter, so i cant go any further without one. unless you have a method of testing without one, i would try anything - almost!!!
 
  #18  
Old 11-02-2009, 12:23 PM
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Originally Posted by Kuroshio
Well the longer it cranks without starting the weaker each attempt will get. The battery will recover given a bit to rest. But the demand on the battery when cranking is huge. Since you tried jumping it with a car battery, I'd say that eliminates your battery as a source.

If the plugs plugs are good and gapped correctly, you could be right. I'd double check the fuel flow just to be sure. Oh and make sure the plug wires are in correct order. I know we're always sure but if I hadn't marked mine, I'd have been sure... And wrong
plugs are good/new, firing order is correct, one coil pack to 1 & 4, and one coil pack to 2 & 3. the only thing in regards to the coils is if there is a designated terminal for + and -? there are no markings on the coil packs. I dont think it would make a difference, and it was not changed before the not starting issue, just a question.
 
  #19  
Old 11-02-2009, 12:38 PM
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Well my Haynes service manual has a whole section devoted to troubleshooting the ignition system. Way too much to try and repost. It did say this though:
Ignition faults can be divded into two categories, namely those where the ignition system has failed completely, and those which are due to a partial failure. The likely faults are
  • Loose, corroded or damaged wiring connections, broken or shorted wiring
  • Faulty ignition or engine kill switch
  • Faulty neutral or sidestand switch
  • Faulty pulse generator or damaged rotor
  • Faulty ignition HT coils
  • Faulty spark unit
Should give ideas of where to look.

But there's nothing in it about measuring peak voltage. All the troubleshooting steps are measuring resistance and voltage. Check if one of the manuals you can download is similar and follow its the diags for the ignition system.
 
  #20  
Old 11-02-2009, 01:29 PM
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i had downloaded a honda service manual. states all the same stuff, but there are procedures and specs on peak volts. the primary builds up to 100V during cranking according to the book - it comes from the CDI.
does your manual tell a resistance for the pulse generator? mine says it should be 280 to 480 ohms @ 20'C
 


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