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1978 9.9hp evinrude idle/start problem

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wildhog

New member
Hi all, I have a 1978 Evinrude 9.9hp model 10835M. It won't start or run unless the throttle is against the neutral throttle stop. When it does run it is rough.
New old stock carb, cleaned all passages.
New plugs
New coils and wires
Compression is 95 top, 92 bottom
I'm baffled that a simple powerhead is kicking my butt. Any advice would be greatly appreciated.
 
To echo Tim, remove the knob from your low speed needle valve and check how it is set. Put a flat blade screw driver on it and count the # of turns required to lightly seat the screw. Typically these are set to 2 turns out from seated. If your needle differs, set it to 2 turns out then retry. There is also the idle adjustment knob on the on the port side. Make sure that linkage is connected and adjusted properly. Since your engine is wanting throttle at low speed, you might need to increase your idle speed knob then back off as needed to get a smooth idle.

KJ
 
Thanks for the replies. The idle air adjustment is out 2 turns. The idle adjustment knob is about a 1/2" away from the arm that it is supposed to touch when the engine is running at idle speed. I see no way to adjust the throttle linkage length or alignment. I have checked for vacuum leaks, none found. New fuel pump, and fuel lines. It acts like the idle circut is plugged up. I have tried 3 carbs on it with the same results. One of the carbs was off of a friends running 9.9. It doesn't have a lean pop but it runs a bit rough from 1/4 throttle to wot.
 
People always pick on / blame the carburetor.------Does spark jump a gap of at least 3/8" on both leads.-----Is exhaust clear ?----Checked the flywheel key?----Has water pump impeller been replaced about every 5 years or so ?-----Checked reed valves ?
 
racerone said:
People always pick on / blame the carburetor.------Does spark jump a gap of at least 3/8" on both leads.-----Is exhaust clear ?----Checked the flywheel key?----Has water pump impeller been replaced about every 5 years or so ?-----Checked reed valves ?
Click to expand...
The spark is nice and blue and will jump 3/8" on the tester. I replaced the impeller a month ago. Pulled the exhaust tube and cleaned it. Put in new Boysen reeds, checked that they seat properly. I also installed a new flywheel key. This motor is new to me so I don't know the history of it's usage.
 
Maybe these will help my explanation. The first pic is where the coil locating ring should be at idle.
The second picture is where the coil locating is for it to start and run at idle.
The third picture is where the idle adjustment is when it is running at idle.
The fourth picture is where the idle adjustment should be at.
Hope this helps.
 
I got the book on it today. It shows adding #2 Permatex where the drive shaft goes into the powerhead. If that has dried up could it be sucking air through there? It would explain why it takes so much throttle to get the air fuel mixture right for it to run.
 
I got the book on it today. It shows adding #2 Permatex where the drive shaft goes into the powerhead. If that has dried up could it be sucking air through there?It would explain why it takes so much throttle to get the air fuel mixture right for it to run. I can't post a pic of what the book showes. Stupid phone.
 
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