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Rebuilt carb issues M27

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Judge1948
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Joined: Wed Nov 29, 2017 7:14 am

Rebuilt carb issues M27

Post by Judge1948 » Tue Nov 20, 2018 5:58 pm

Zenith updraft has been rebuilt. Great throttle response and smooth acceleration. Hits about 33-3400 no problem. Very smooth and effortless. Two problems. Won’t idle well below 1000 or 1100 rpm. For a short time,once maybe, it was good at 800-850. Not anymore. 1000 that’s it. Starts and shuts down well. Also when standing starboard next to engine she idles fine but if I move my weight to port she wants to die. Seems to me the float could be a problem, set to high? The idle I’ve got no idea. Any ideas? I need to get this right. Rebuild guy has offered redo carb but maybe I can handle this here. Thank you
1948 Chriscraft U-22
Hull # 1064

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Captain Nemo
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Joined: Tue Jul 07, 2009 7:40 pm
Location: Lyons, NY

Re: Rebuilt carb issues M27

Post by Captain Nemo » Fri Nov 23, 2018 1:23 pm

73 views, no responses. I'll take a stab at it. 1000 rpm's in neutral is about where you want an idle.
How much fuel is in the tank? Check for any water or stuff in the Tank? Your pickup tube is on the Portside I think. So, standing on the Portside with an empty tank might float something towards the tube and plug it?
Just throwing this out there. :roll:
Boats are to be made of wood, otherwise, God would have grown fiberglass trees.

jim g
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Joined: Wed Dec 14, 2011 10:55 pm

Re: Rebuilt carb issues M27

Post by jim g » Sat Nov 24, 2018 1:45 pm

Yep. A 1000 rpm at idle should give you around 700 to 800 in gear which is what you want. Also as Nemo check your fuel level. I doubt float level is causing it. unless its set way to low. In which case it should be running out of fuel at speed.

When was it tuned up last? If its been a long time then that could be the cause of your idle problems.

Judge1948
Posts: 12
Joined: Wed Nov 29, 2017 7:14 am

Re: Rebuilt carb issues M27

Post by Judge1948 » Sun Nov 25, 2018 4:45 pm

Well the engine received a complete overhaul in June. Complete tear down and rebuild of all components needing work. Carb points rotor cap. 12 volt conversion. It did idle at the 850 900 which is what builder said is desired. Just seems that 1000 is a bit high but IDK...it drops to around 900 in gear. To be clear 1100 to 1000 out of gear. I worked the tank, it has been boiled and lined. All parts cleaned and reinstalled. When re builder had boat tank came out to install blowers and external fuel filter system. Unsure if anything was done in their end. Tank is 3/4 full. Again she runs great but this stall thing when standing on port just seems wrong. I suppose I could drain and pull tank to check condition and contents. Usually I keep about half a tank (15gal) all the time. I’m not using any corn gas. Any reason NOT to have him rebuild carb?? Also idle jet is all but closed. Turn and a half is recommended but I’m using quarter or less. Not nearly the suggested setting... but that’s what she likes. So that would mean I’m keeping air mix less than suggested right? Would a pin hole on float cause any trouble?
1948 Chriscraft U-22
Hull # 1064

Judge1948
Posts: 12
Joined: Wed Nov 29, 2017 7:14 am

Re: Rebuilt carb issues M27

Post by Judge1948 » Sun Nov 25, 2018 4:56 pm

Also I would be remiss if I did not say thank yuh for your well qualified information and experience. So I thank you.
1948 Chriscraft U-22
Hull # 1064

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Captain Nemo
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Location: Lyons, NY

Re: Rebuilt carb issues M27

Post by Captain Nemo » Sun Nov 25, 2018 7:09 pm

Yuh welcome :). You seem to have the tank clean enough and have gone thru the fuel system. The idle jet screw adjustment seems to be a clue. I think it might be a good idea to check back w/ the rebuilder, he should be able to sort this out. It's hard for anyone to diagnose something from this side of the keyboard. Good luck, let us know whatcha find out.
Boats are to be made of wood, otherwise, God would have grown fiberglass trees.

Judge1948
Posts: 12
Joined: Wed Nov 29, 2017 7:14 am

Re: Rebuilt carb issues M27

Post by Judge1948 » Mon Nov 26, 2018 10:33 am

Agreed. I’ll repost when I know more.
1948 Chriscraft U-22
Hull # 1064

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