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50hp Starts and then shuts off

C

Cole R

New member
I’ve been messing around with my mercury 50hp for the past few days whenever I go to start the motor i prime for about 10 seconds, turn to 1/3 throttle and it starts right up. Immediately upon start up it bogs down and then cuts off. I’ve checked everything in the fuel system: no lines are clogged, new fuel filter, carbs cleaned. The motor has good compression on all 3 cylinders as well as strong spark. Any ideas on what the culprit might be?
 
Cole R said:
I’ve been messing around with my mercury 50hp for the past few days whenever I go to start the motor i prime for about 10 seconds, turn to 1/3 throttle and it starts right up. Immediately upon start up it bogs down and then cuts off. I’ve checked everything in the fuel system: no lines are clogged, new fuel filter, carbs cleaned. The motor has good compression on all 3 cylinders as well as strong spark. Any ideas on what the culprit might be?
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Motor is a 2003 50hp 2 stroke
 
Fuel Pump? The start comes from the squeeze bulb. Once the engine starts it's up to the fuel pump to keep it running....you touched all the other bases other than maybe a deteriorated fuel inlet hose...did you cut the fuel filter open and observe the contents?
 
Motor should run at least a few minutes on the gas in the bowl. I'd expect a blockage in the idle circuit in the carburetor. In the picture attached of your carburetor, you need to take parts 9 and 10 off and clean the tiny passages under the cover and gasket. You might have to run a small wire through tiny passages. You are starting the motor by opening the throttle enough for the main jet to feed the cylinders with fuel, but once you reduce the throttle, you're attempting to use the smaller idle jets (or passages) which are apparently clogged.
 
Oldsaltydog said:
Motor should run at least a few minutes on the gas in the bowl. I'd expect a blockage in the idle circuit in the carburetor. In the picture attached of your carburetor, you need to take parts 9 and 10 off and clean the tiny passages under the cover and gasket. You might have to run a small wire through tiny passages. You are starting the motor by opening the throttle enough for the main jet to feed the cylinders with fuel, but once you reduce the throttle, you're attempting to use the smaller idle jets (or passages) which are apparently clogged.
Click to expand...
Along the lines of what you said, I had an intermittent loss of power at higher RPMs on a carbed engine. I thought I had one of the carbs completely cleaned and decided to give it one more blast of 100 PSI air.....low and behold this little black speck of decomposed internal fuel line came sailing out of the high speed jet area located in the bottom of the bowl. Had I not decided to give it one more blast I wouldn't have found my problem. The wire in tiny orifices is always a great idea followed by blasts of compressed air.
 
racerone said:
What do you mean when you say ---" prime for 10 seconds " ?
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Oldsaltydog said:
Motor should run at least a few minutes on the gas in the bowl. I'd expect a blockage in the idle circuit in the carburetor. In the picture attached of your carburetor, you need to take parts 9 and 10 off and clean the tiny passages under the cover and gasket. You might have to run a small wire through tiny passages. You are starting the motor by opening the throttle enough for the main jet to feed the cylinders with fuel, but once you reduce the throttle, you're attempting to use the smaller idle jets (or passages) which are apparently clogged.
Click to expand...
Thank you I will keep updated
 
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