5th Gen Cranks but will not start

Discussion in 'Mechanics Garage' started by razzman, Nov 29, 2012.

  1. razzman

    razzman New Member

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    Went to start my 2001 Gen 5, engine was cranking and firing but having difficulty starting. After cranking for 10 seconds the sound changed like the engine was not firing anymore and all I could hear was the starter and engine turning over, but no firing. I could smell gas.
    I checked that the fuel pump was priming for (5 seconds) after turning on the key. Checked power at the pump as well and was fine. Checked power on all the coils and was receiving sufficient voltage. Tried again another time, and then pulled each plug and held against engine to check for spark. All plugs were wet, and were giving a spark. Charged battery to ensure it was not the issue. Cranks over the engine just fine, but does not start. I followed the troubleshooting steps in the manual and tested voltage at the coil. I don't have a peak adaptor, but hooked up a capacitor to get a better reading (in lieu of the peak adaptor) on my meter figuring I could get a closer reading. Checked the ignition pulse generator voltage and seemed a bit low. Found a used one and slapped it in, but that was not the issue. Guess I was not getting a true indication of the voltage due to the speed of the pulses. I am not getting any FI flashing error indicators.

    I have not checked fuel pressure or flow yet, I don't know what size adaptor I need to do this. Bike was not sitting before this happened, and is (or was) pretty much a daily driver. Tank was half full when this occurred. Bike has about 35K, so still low miles. Is there any other obvious things I should check, perhaps things systemic to this gen of VFR? I would like to fix it, but getting close to taking it to the shop.

    Thanks
     
  2. Maggot

    Maggot New Member

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    Just a guess here. You have ignition and you have gas. The only thing that may be missing is air. Check the air box and filter for pests. FI enricher problem? Thats all I got! Good luck.
     
  3. Scubalong

    Scubalong Official Greeter?

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    +1 These little critters know how to find their way in there.
    Be patient let diagnose one thing at a time.
     
  4. mastergregor

    mastergregor New Member

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    Hm, I am not sure blocked air delivery would cause sudden no-start condition. If filter was getting dirty, or if some pesky rodent would infiltrate the air premises, it would be running rough, but I doubt it would be a no-start altogether. However, I could be wrong ....

    Fuel pressure would be good to check. Low pressure, for whatever reason, will cause no start.

    Another thing is choke, make sure your wax element (auto choke) is working and opening the valves on the throttle assembly.

    A weak spark will also produce no-start. Testing spark level would also be good. Sometimes just grounding the spark plug and watching for spark does not give you idea of how strong spark is. A nifty little $10 device will give you an idea about spark voltage, something like this:
    Amazon.com: OEM 25069 Adjustable Ignition Spark Tester: Home Improvement

    Timing is another issue that comes to mind, although I am not sure it would be sudden like that, since gears do not skip as easily as belt. It is easy enough to check though, you can rent a timing gun if you do not have one.

    A stretch might be compression in cylinders, but again, on a V engine with two independent banks of cylinders and heads, I doubt compression would suddenly drop and cause no-start.

    That is about all that comes to mind right now ...

    Let us know what you find out.
     
  5. razzman

    razzman New Member

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    I will have a look at the airbox to rule everything out, but I was in there a few months ago as part of a tune up,so I would be surprised it that is it, but I can't rule it out if I haven't looked. Thanks for the tip.
     
  6. razzman

    razzman New Member

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    So pardon my ignorance, the ignition tester looks cool, but I can't wrap my head around how it works. How does this differ from looking for a spark on the plug? Is it interpolated? I.e. a .25" gap set on the tester to test for sufficient power for an actual .036" spark plug gap?

    Thanks
     
  7. mastergregor

    mastergregor New Member

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    The ignition tester tests the voltage of the spark. Roughly, for every centimeter of air 10k volts is needed to create a spark. For instance, if you cathode and anode are 2cm apart, you need 20k volts. The ignition tester uses this physical property of electricity in order to measure the strength of a spark. To be more specific, it has a screw that is screwed or unscrewed to decrease or increase the distance among the contacts, and you observe the spark between them. Once you see no spark, you determine your distance, and thus, a strength of a spark.
    On a more practical level, you plug one side of the tester into the plug boot, and ground the other end, meaning you do not need to pull the spark plug out itself.

    I am not really sure there is a correlation between a spark strength and spark plug gap. I think a better correlation is between spark strength and volume of combustible mixture, but I do not know the exact numbers, so I can not really help you there :(

    What I can say is that on older, distributed cars, spark is around 15k-20k volts, while on transistor ignitions it is ~25k-30k. Newer systems, like coil-over-plug go up to ~40k, which gives better combustion, cleaner and more through. Now, if you want to go even more exotic we can go into airplane engines, multi-port ignitions, etc. :)

    I mentioned strength of spark as possible issue because I have seen it before. A "partially" shorted cable from coils to the plugs will sometimes weaken the spark, for instance if insulation degrades and develops cracks. These conditions are known to create no-start due to ignition.
     
  8. mastergregor

    mastergregor New Member

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    Crap, I just checked the link you posted. Let me clarify, there are many types of ignition testers, the one I was talking about and the one I use for "measuring" the spark has a screw and a sight glass for the spark.
    Other types vary, and some of them just detect the presence of spark, but I am not sure how to reliably verify that spark is indeed strong.
    Maybe someone else has better experience with other types of spark testers and can elaborate more.
     
  9. squirrelman

    squirrelman Member

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    Reset plug gaps to .032"
     
  10. taylor65

    taylor65 New Member

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    Have you checked your safety switches? Like your kickstand switch or clutch switch for a short or dirty contacts. All I have right now
     
  11. RC30guy

    RC30guy New Member

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    I was going to say kickstand kill switch or blocked fuel filter as I have had both happen.
    Today had my Reg Rec go bad on my 94 VFR while driving, knew it was that as it ran the battery flat.
    Luckily learned the hard way 2 years ago on my 98 VFR when its Reg Rec died.
     
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