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carb problem

DJF

Member
1982 mercury 80 hp , Motor starts great won't idle below 1000-1100 rpm , top carb adjusted 1 1/2 turns out, bottom carb adjusted all the way in to run best . What causes this ? I am New here
 
Wires were bad , so replaced all electrical. compression was around 150 on all cyl. spark was good on all , rebuild carbs . checked reeds all good.
 
Wires were bad , so replaced all electrical. compression was around 150 on all cyl. spark was good on all , rebuild carbs . checked reeds all good.
 
I split the crankcase and used a snake camera and feeler gauge to check reed stops and reeds and reed blocks , all looked like new and checked out to specks.(I am a retired Auto & Diesel Mechanic - Machinist ) checked and replaced all gaskets and seals. Had the carb problem before and still do. Never been inside a outboard before ,Keeps this old man busy & happy.
 
Check that the carbs are fully closed and that they open at exactly the same time. Idle speed is dependent strictly on ignition timing. Do you have a manual that explains how to set the throttle pickup. Mercs can be tricky getting the sync and max spark advance. What is the serial number of your motor?
 
primer bulb gets hard , filter is full of fuel. pulled the bottom carb ,full of fuel , cleaned and check in out , reset float found not problems with carb. fuel pressure good. will re install carb tomorrow and recheck throttle adjustments and recheck timing ???????????
 
Both carbs must be fully closed to adjust the slow needles is the throttle cable disconnected? Loosten the idle stop screw and back off until it no longer touches. Preset the slow needles out 1 1/2 turns from lightly seated. Follow the instructions on how to sync throttle opening to spark advance. Once it is fully warmed up adjust the slow needles in forward gear with a load on the prop either in a barrel or on the water. Point ot toward the big part of the lake and check adjust max spark advance. After each adjustment disconnect the throttle cable to confirm proper idle speed and adjust the cable as necessary. It could be as simple as a cat hair in the float needle your just missing a step. High idle issues are always too much fuel or spark advance.
 
Looking at the welch plugs on the carbs got to thinking they may be sucking air so I sealed them with gasket sealer and now the carbs adjust like they should. runs good but still idles around 1000 rpm . could the jets cause the fast idle if the main jet and the vent jet was reversed ????? Thanks for info
 
idle stop set, throttle cable disconnected, carbs closed all the way ,still can't get below 1000 rpm ,in or out of gear
 
Did you get the timing to retard? Is the cavitation plate at least 5 inches under water when in forward gear as you adjust the slow needles?
 
timing calls for 2 btdc to 2 atdc runs best 2 to 4 atdc, still fast , running with out the prop on ,this would cause faster rpm , but would prop on drop it 400 rpm??? cavitation plate is 4 inches under water. How do I test for sticking trigger ? trigger is new
 
Is there an adjustment between the trigger and the spark advance lever? Are all the bushings tight well greased and operating smoothly? Sounds like you had it all apart but even if you took picks there is no guaranttee it was correct before you took it apart. Keep at it you will get her dialed in eventually!
 
no adjustment on the trigger to spark advance lever, bushings are tight , the throttle cam is a little sloppy but with throttle backed off this would not affect idle.
 
To protect the engine and help on cold starts adjust the slow needles for the smoothest lean setting on both carbs the add 1/8 to 1/4 rich. Adjust the needles slowly 1/8 turn at a time and wait between adjustments for the crankcase to stabilize 5 to ten seconds.
 
Idle timing is on the cover over the carbs, same as in manual, have a very good manual , came with the outboard in 1982 about 2 inches thick covers modles from 75 hp to 150 hp the manual is probably worth more than the motor. everything is back together the way it should be .
 
need to run and adjust it on the lake, with 3 feet of snow , and the water is a little hard it'll be a few months, live in Montana. thanks for your input
 
When the weather clears up--about August!--try running the motor at idle off the fuel tank.: Hook it right to the carbs and GENTLY work the bulb. If it runs okay, replace the fuel pump.

Hell, you got nothing to do for months so why not just do it now?

Jeff

PS: My wife and I just LOVED Montana.
 
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