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fishingpapa

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Need some help, please! 79 Johnson 175 HP. Pulled the top and bottom carbs to replace all fuel lines. New carb to manifold gaskets installed. Didn't do anything to carbs. Linkage is free, and appears to be correct. Throttle cam is not touching linkage. Throttle butterflies closed fully. Carbs synced. cannot find any air leaks at base of carbs. Advance is bottomed out. Motor was idling fine, on muffs, five minutes before I pulled the carbs. Motor is now idling at about 1700-2200 rpm on muffs. Could it be a stuck float, something else? Any ideas? Thank you!​
 
I would double check the carb butterflies are closed. Did you do the link and sync? Make sure the throttle cable is not misadjusted.
 
Thanks for the reply. I have double and triple checked the butterflies. I have all but hammered them closed. Throttle flies are fully closed, choke flies are fully opened. I have run it with linkage disconnected, throttle cable disconnected, manually pushing all 3 throttle flies closed while running and advance to full retard stop positions. Throttle springs are strong and flies snap shut. I am at a loss. If you have any ideas, I would love to hear them. Thank you!!.​
 
fishingpapa said:
Need some help, please! 79 Johnson 175 HP. Pulled the top and bottom carbs to replace all fuel lines. New carb to manifold gaskets installed. Didn't do anything to carbs. Linkage is free, and appears to be correct. Throttle cam is not touching linkage. Throttle butterflies closed fully. Carbs synced. cannot find any air leaks at base of carbs. Advance is bottomed out. Motor was idling fine, on muffs, five minutes before I pulled the carbs. Motor is now idling at about 1700-2200 rpm on muffs. Could it be a stuck float, something else? Any ideas? Thank you!​
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I suspect an intake manifold leak. Sometimes a leak can be detected by spraying WD40 around the base of the carbs and listening for a change in R.P.M. Be sure to check any vacuum hoses for cracks and deterioration.

Bill
 
Ram Jet said:
I suspect an intake manifold leak. Sometimes a leak can be detected by spraying WD40 around the base of the carbs and listening for a change in R.P.M. Be sure to check any vacuum hoses for cracks and deterioration.

Bill
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Bill, thanks for your input. I have sprayed carb cleaner all around the base of carbs and lines with no obvious change in rpm. I had changed fuel lines but still have one line that runs from fuel pump to crankcase (?) but no other lines that run to manifold or obvious vacuum lines. This is a 1979, so not a lot of lines, pretty basic.
Kirk
 
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