Mercruiser 3.0 1987 engine not running well after warmed up

A

alpha-newbe

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May 27, 2025
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Engine idles fine and will run smoothly at lower rpm in neutral and in gear. After running smoothly on the lake for 15 min or so at 3500 rpm then running for 15 min at 1000 rpm smoothly all is good. Then i go to running at 3500 rpm again and it runs rough so i back the rpm's down to 1500 again and it runs smooth. So then i just take if back off the lake because it is not running well.
 
alldodge

alldodge

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Might be a fuel pressure issue (pump or fuel lines) but when was the last time the carb was cleaned?

Have you checked the points and the dwell
 
A

alpha-newbe

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May 27, 2025
Messages
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alldodge said:
Might be a fuel pressure issue (pump or fuel lines) but when was the last time the carb was cleaned?

Have you checked the points and the dwell
Click to expand...
Thank you alldoge! I currently have a carb rebuild kit and will plan to start there. Then fuel line checking and main fuel filter at base of engine. Already changed the small filter screen at the fuel inlet to carb.
 
A

alpha-newbe

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Joined
May 27, 2025
Messages
17
alpha-newbe said:
Thank you alldoge! I currently have a carb rebuild kit and will plan to start there. Then fuel line checking and main fuel filter at base of engine. Already changed the small filter screen at the fuel inlet to carb.
Click to expand...
New distributor cap, plugs, wires, condensor, and new rotor arm with gap set to Merc spec., ignition coil, and starter solenoid.
 
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