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25 hp mariner carb issues ????

D

dtoole

Regular Contributor
HI all , its been awhile since ive been on here. i have a 25 hp mariner ( serial number OG115780 ) that im having trouble getting to run right. i first checked compression ( 90 psi on both cylinders ), checked for spark (jumps 3/8 gap bright blue ).the owner said the carb needed rebuilding. when i tried to crank ,it would not. i pulled the carb and bought a rebuild kit. soaked the carb in my ultrasonic cleaner and blew all passages with air and carb cleaner. then reassembled. with the primer pulled out the motor will run. not great but it will idle and run. when i push the primer in , it speeds up after a few seconds and then shuts off. i think its running off the primer circuit. when i close it, i think it runs out of fuel. it will not refire unless i pull the primer back out. i pulled carb back off to see if maybe the check ball was stuck open or something. i found no problem. i know there are some really sharp guys on here, im hoping for some food for thought. thanks david. one more thing, im running the motor in a water drum and after maybe 5 min run time, the top of the tank is covered in oil. running way too rich?
 
First of all. 90 pounds is pretty weak--mine had that and ran okay, but was a dog.

It sounds like your idle mixture screw needs to be out a bit more. I hope you're not going by the book, with it "X" turns out; that's just for a rough set up. Turn it out at least 2 full turns and see if that helps.

Jeff
 
Hi jeff. Good to hear from you.i tried setting the idle mixture screw from all the way in to maybe three turns out.. it will not stay running with the primer/enrichment not activated.it seems to me that its not getting enough vacume through the carb to pull fuel.does thaat sound reasonable? Maybe an air leak in the reed pkate or a blown crank
 
Hi jeff. Good to hear from you.i tried setting the idle mixture screw from all the way in to maybe three turns out.. it will not stay running with the primer/enrichment not activated.it seems to me that its not getting enough vacume through the carb to pull fuel.does thaat sound reasonable? Maybe an air leak in the reed pkate or a blown crankcase seal?
 
Fuel bowl is full. Tried pumping primer bulb.it stayed firm. I agree that it is running out of fuel.like i said it will not pick fuel up through the idle circuit nor through the main jet.. when i pulled the carb the second time the fuel bowl was full of gas.
 
i wanted to take a second to thank fastjeff and racerone for your thoughts. i also wanted to let you know that the little motor is running fine. after work today i pulled the carbs again along with the reed plate. i found the gasket on the reed plate was in fact leaking. it was loose and wet along the bottom edge.after a little cleaning and sealer,the motor runs fine.thank yall again. david
 
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