MSD - no spark
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MSD - no spark

  1. #1
    Boat 502 76Miller's Avatar
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    Angry MSD - no spark

    My current set up is 7ml-2 ignition box, hvc-2 coil, start retard box, and billet pro dizzy(locked out). I lost spark and thought it was the box had it tested by MSD and it checked out. I guess you need a special tester because they say a multi meter won't tell you if the box is working properly ?? Doesn't make sense to me but..... So, I tested the coil, then I put in a new pickup. Everything tested out ok, but boat will not start ? I pulled the coil wire, set near ground, cranked it over and I get "single spark" then its dead. So, I put a different coil in the boat and it did the same thing. I can crank it over for 5-6 seconds and I get nothing, just initial spark ????? I have heard of no spark, but " one spark " then nothing ?? Could this be the key switch going bad ? I do have the acc. on the key switch powering quite a few things but the boat has worked like this all season long.Thanks for any help.

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    Cantard 71hallett's Avatar
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    I would jump the little red to hot feed and see what happens. Bet your on to something with the key.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Senior Member GT Jets's Avatar
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    It really sounds like a bad ground...I would be curious to see what a jumper does though...The dizzy does turn right (stupid question I know)..

    GT

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by 71hallett View Post
    I would jump the little red to hot feed and see what happens. Bet your on to something with the key.
    Forgot to mention, but that was the last thing I tried before I had to go to work. Same thing, single spark then nothing. I'm wondering if this key switch is just going bad or if I have it doing to much work. It powers quite a bit, acc sends pwr to : gauges, pwrs kill switch, pwrs n20 purge(switch), pwrs arming switch for n2o system. Then, starts the boat w/ the next click. But.....its worked all season ???

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    Cantard 71hallett's Avatar
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    Quote Originally Posted by 76Miller View Post
    Forgot to mention, but that was the last thing I tried before I had to go to work. Same thing, single spark then nothing. I'm wondering if this key switch is just going bad or if I have it doing to much work. It powers quite a bit, acc sends pwr to : gauges, pwrs kill switch, pwrs n20 purge(switch), pwrs arming switch for n2o system. Then, starts the boat w/ the next click. But.....its worked all season ???
    Can you disconect the spark retard?
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by GT Jets View Post
    It really sounds like a bad ground...I would be curious to see what a jumper does though...The dizzy does turn right (stupid question I know)..

    GT

    Yep, its turning. The ground on the box goes straight to the block and its got 12.5 volts. When the motor is cranking it drops to 10 volts, but it has always been that way.

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    Senior Member Oldsquirt's Avatar
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    It is true that you cant test the box with a volt/ohm meter. Typical electronic ignition testing has always been to eliminate any problems in distributor/coil/wiring and if all are good "replace ignition module with known good unit".

    As for the "single spark" issue, that is something I have generally found relates to a distributor that is not turning and, therefore, not sending a signal to the module. Being I'm an import tech, the usual cause would be a broken t-belt which was generally obvious by the sound of no compression while cranking. Since you replaced the pickup, I assume you verified the distributor actually turns while cranking? You may want to check the resistance of both the old and new pickups. Spec should be available on MSD's website.Do a visual on the harness and connections between distributor and MSD box. The test 71Hallett
    suggests is a good idea as well.

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    Cantard 71hallett's Avatar
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    I also think that those boxes need atleast 9 volts to fire.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by 71hallett View Post
    Can you disconect the spark retard?
    I could, but I tested it w/ the jumper wire test that msd's web page recommends and it sparked like crazy, and its conected to the 7al box which is grounded to the block. It also really helps the boat start because it pulls 10* of timing when cranking (locked out timing).

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by 76Miller View Post
    Yep, its turning. The ground on the box goes straight to the block and its got 12.5 volts. When the motor is cranking it drops to 10 volts, but it has always been that way.

    Does the dizzy have a good ground?..When you find it you'll kick yourself in the head

    I had a bad rev limiter chip that made the motor backfire, pretty weird...

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    Boat 502 76Miller's Avatar
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    Old squirt-

    Ya, the tech told me that you can check pwr going into the box but the only terminal on the box that will show pwr is the ignition terminal. Every other terminal will show dead, even while cranking. Would the ''single spark'' be caused by a bad cap or rotor ? The dizzy is spinning when cranking and I checked the resistance on the new pick up and its good. Keep the options coming ! I know its something simple.

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    Senior Member GT Jets's Avatar
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    Have you diconnected the tachometer lead? The tach could have shorted...

    It will be something dumb, but IMO not the rotor or cap...

    GT

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    Cantard 71hallett's Avatar
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    Quote Originally Posted by 76Miller View Post
    I could, but I tested it w/ the jumper wire test that msd's web page recommends and it sparked like crazy, and its conected to the 7al box which is grounded to the block. It also really helps the boat start because it pulls 10* of timing when cranking (locked out timing).
    Only reason I ask is because I had a timing controler act up and it would do the same kind of thing. No start. Would short the white wire and kill the signal.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Boat 502 76Miller's Avatar
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    Quote Originally Posted by GT Jets View Post
    Have you diconnected the tachometer lead? The tach could have shorted...

    It will be something dumb, but IMO not the rotor or cap...

    GT
    Your on it GT ! Thats what a buddy said too. I'm trying that first thing tomorrow (@work all night) . Any other thoughts ??

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