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Loading up @ low RPM? |
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ChowHound 
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Joined: July-25-2013 Location: NEast Status: Offline Points: 47 |
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 Topic: Loading up @ low RPM?Posted: June-10-2014 at 12:35am |
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Hey Folks...
I'm hoping for help in identifying possible culprits of the following symptoms. Test case: 87 Nautique, 351. Symptoms: *(new this season) Slight trouble keeping idle on cold start. *(new this season) Slight smell of unburnt fuel in exhaust at idle speeds *Seems to be loading up after extended low RPM operation (putting / surfing) *Erratic idle setting. Setting may hold for a couple days, but needs to be knocked back, or up (about the same amount) every now and then. Runs fine at wakeboard speeds and higher. Generally runs really smooth. I bought it last August. Replaced spark plugs last season. I pulled distributor cap today, some wear on rotor/cap. Condenser/points look fairly new (still shiny). I didn't dig as far as the advancement weights. I'm thinking a weak spark condition...any other thoughts? Hopefully soon, I'll know enough to offer help instead of ask for it. Thanks! -Chow |
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TRBenj
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Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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Posted: June-10-2014 at 10:01am |
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A complete ignition tune up is in order before you do anything. A carb rebuild wouldn't hurt either. Troubleshooting problems when a new-to-you engine is in an unknown (or known to be poor) state of tune is a total crap shoot.
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: June-10-2014 at 10:03am |
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Could be a leaky carb. After shutting down the motor, remove the air cleaner and look down the venturis. If you're getting some drops coming out of one of the boosters, you probably have a float level or needle and seat issue.
There are other possibilities too, but let's start there. Also, this little Thumbscrew makes removing the flame arrester frequently, easier. |
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ChowHound
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Joined: July-25-2013 Location: NEast Status: Offline Points: 47 |
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Posted: June-10-2014 at 11:37am |
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thanks for the tips!
I agree about some ignition component replacement. I'll be ordering a cap/rotor/wires today. The condenser and points are pretty recent. I also got into the advancement weights and they're in good shape, moving nicely. I was also thinking about replacing the resistor that resides near the starter solenoid. I'm assuming it's original....would that contribute to any of my symptoms if bad? and oh, I did a replaced the coil last year with one for SkiDim. Thanks for the tip on diagnosing floats/seats...and just as importantly, the tip on that thumbscrew. Just last night i was remembering my 77 had a wing nut - this is even better. Thx!!! -Chow PS: another thing i noticed is the Tach is acting a little wonky this year. Not sure if related but, figured I'd toss it out there for consideration. |
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TRBenj
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Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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Posted: June-10-2014 at 12:03pm |
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Setting proper dwell and timing are also part of an ignition tune up... Don't forget that.
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ChowHound
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Posted: June-10-2014 at 12:09pm |
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i was hoping i could forget that
;) I've never messed with dwell but I do have a timing light. I'll have to look up the stats. thx! |
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