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  1. #1

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    RXTX 260 RS - RPM Jumps and drops... Irregular idle

    Good day gents...

    So this morning, I took the ski for a test run... It was last used 11 months ago, but I did start it occasionally during the off season...

    So initially, while going at WOT, the revs would go up to 7400 then drop to 5000, then back up to 7400 and drop back to 5000... This continues and the top speed not more than 35mph. I decided to go to the side of the dam, and install new plugs which I have in the nose storage.... Unpacked everything and discovered my spark plugs are not with me, probably at home

    So I get back up, start and go... All of a sudden, the rpm jumping is now gone, and she goes at a constant 7600 rpm (we are 1400m above sea level, so the 7600 is fine)…

    So all seems good, and I'm not sure what caused the intitial RPM jumps...

    I have noticed that she does not idle very smoothly... Almost like a little bit of a miss fire... Anything I can check??

    I will do the following in the next couple of hours:
    -Check spark plugs (visually)
    -Remove and pressure test IC

    Anything else I could check?

    Thanks


  2. #2
    Xspook's Avatar
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    I've had plugs that look great, but still needed replacing. Start with that.

    Also, how fresh is the gas?

  3. #3

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    Ok... So an update...

    The spark plugs looked good, but for $10, I just replaced them anyway....

    I removed the IC and did a pressure test... NO LEAKS

    After installing the intercooler and putting the battery back in (I removed the battery to try and give myself some more space to work with)… I tried to quickly start her just to check...

    Dash lights up, reads key... And when I push start button, only "click", then dash reboots...

    Check fuses, all good... Tried to bridge starting relay to turn starter, and every time I do this, I hear an electrical "spark" of some sorts close to the fuses... Obviously, this sounds like a fuse being blown, but I can't seem to find the fuse that keeps on blowing...

    I decide to remove the battery again to start looking at cables, and then I saw it...

    Ground cable corroded so badly, that it just snapped of at the terminal...

    I'm not sure if this caused my idling issues, as I can't really check this out of the water... I need to go do a dam test again... But it sure as hell would have left me stranded 20 miles offshore while on a fishing trip...

    She now starts well, and EVEN better than before... She always sort of struggled to start, as if the battery was not good, even though the battery was new... I guess this corrosion have been there for a while which limited the starting current... I had to replace the complete cable, the corrosion went about 1.2m up in the cable...


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  4. #4

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    Quote Originally Posted by Xspook View Post
    I've had plugs that look great, but still needed replacing. Start with that.

    Also, how fresh is the gas?
    It had a little bit (two bars) of old gas (11 months old), which I diluted with a 1/4 tank of fresh gas...

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