Rpm fluctuation
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Rpm fluctuation

  1. #1
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    Default Rpm fluctuation

    While crusin @ 3000 suddenly gain 200 rpm. Stays awhile then drops back. If I pull back throttle will reduce but will later drop 200 rpm. Feels and sounds good elsewhere. Wondering if it might be a intermittent plug wire problem. Any suggestions?

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    Senior Member 74Bonneville's Avatar
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    I'm pretty sure its not your plug wires. Maybe fuel system.

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    Senior Member wpmxwb's Avatar
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    What carb is on it?

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    It has the same carb it's always had on it. It's a holley 750 with vacuum secondaries. At 3000 rpm I'm not close to the secondaries opening. This rpm changes sometimes happens @ other RPM's. I notice it most when just leisurely cruising. All off a sudden it will gain 200 rpm. If left alone it will usually drop back down within minutes. It will cycle like this over and over. If I pull back the throttle to original rpm it will later just drop back the 200 rpm. and I'll have to give it more throttle to regain the original rpm set.

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    Senior Member SBS933's Avatar
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    Replace your plugs, wires and cap and rotor. I had a plug problem in the past and I would lose 250 RPM per plug. It would start with one plug fouling out and then cleaning up, only to finally losing 2 plugs on a run. I went back to hotter plugs and problem solved.
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    Senior Member Futs's Avatar
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    Quote Originally Posted by 74Bonneville View Post
    I'm pretty sure its not your plug wires. Maybe fuel system.
    Really? I just had this same problem last weekend on my little LS. I had burnt through 2 plug wires and didn't even notice. I replaced the wires and it fixed the problem.

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    gn7
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    Quote Originally Posted by Futs View Post
    Really? I just had this same problem last weekend on my little LS. I had burnt through 2 plug wires and didn't even notice. I replaced the wires and it fixed the problem.
    Damn LSs are pure magical.



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    Quote Originally Posted by gn7 View Post
    Damn LSs are pure magical.
    Yes they are Bob...... I really enjoy mine, but its bone stock.

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    Quote Originally Posted by Futs View Post
    Really? I just had this same problem last weekend on my little LS. I had burnt through 2 plug wires and didn't even notice. I replaced the wires and it fixed the problem.
    hummmmmmm sounds familiar: from years past


    two other wires were shot, but not as bad as that one. Engine didn't want to rev much at all ....
    Last edited by Sleeper CP; 07-26-2013 at 11:07 PM.

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    gn7
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    Quote Originally Posted by Sleeper CP View Post
    hummmmmmm sounds familiar: from years past


    two other wires were shot, but not as bad as that one. Engine didn't want to rev much at all ....
    That's what you get for not running a LS Jon. You could have redlined that thing for another couple outings before replacing it, and still kept it as a spare.



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    Quote Originally Posted by gn7 View Post
    That's what you get for not running a LS Jon. You could have redlined that thing for another couple outings before replacing it, and still kept it as a spare.
    them things are just a miracle engine ......... they could probably part the sea if you asked.

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