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Uneven low revs?

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Old 12-29-2008, 01:10 PM   #1

DGR-Z246-98 is currently offline
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Default Uneven low revs?

Hello All,

Have had a bit more time running in the rebuild and paying more attention to the rev dropping, here's the description so far, any ideas?

Normal idle at 600 RPM when at running temp.

If revs are in the range of 750-1000 (approx 5 knots) she will not hold steady and bounces between 600 and 1100 at roughly 2-3 second intervals.

Anything over 1000 and she runs smooth, idle also smooth. Just in that range, either hot or cold she jumps about. Makes the trip through the harbour a little entertaining to say the least!

Any ideas from the experts?

Thanks in advance,

Steve.
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1998 Z246 (Merc 5.7L BI)
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  • Old 12-30-2008, 12:41 AM   #2

    300sflyer is currently offline
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    Sounds like a small vacuum leak to me. Check to make sure all of the intake bolts are tight [preferably with a torque wrench to specs] and also the 4 carb bolts. [Unless its fuel injected]

    If you don't find anything loose, I'd have the guys who rebuilt the engine have a look at it.

    Let us know how you make out.
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