Merc 140 Fuel System Question ?

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lucey

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Jul 14, 2002
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I have been having this intermittent problem with my Merc 140. Once in a while when i put the coals to her it will bog. I redid the ignition and the problem still is happening. I am about to rebuild the carb but i am thinking it may be something else. Today at the lake i filled the boat with 92 premium gas almost to the top. The boat ran absolutely perfect until i got down to between 1/4 and 1/2 tank. Then the bog reappeared. Why when full is the boat running that much better. When it gets down on fuel the idle is worse and the bog returns. I have only tried filling it once so i am not sure if it is coincidence. Any ideas ?
 
Bob_VT

Bob_VT

Moderator & Unofficial iBoats Historian
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Re: Merc 140 Fuel System Question ?

Accelerator pump. Common problem in the carb and seems to come and go. I have repaired 4 differant mercruisers with the same problem over the years.<br /><br />I ordered the parts through a local NAPA parts store here.<br /><br />Bob
 
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ebbtide176

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Re: Merc 140 Fuel System Question ?

hope you're back on the water soon. if you have any other problems, post them! it's been said here that even something as simple as your brand of oil might cause problems...
 
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chesire

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Re: Merc 140 Fuel System Question ?

I had the same problem you are having. Also a 140 merc I/0, 1986. I replaced all the fuel<br />lines rebuilt the carb, replaced all the filters. You have 2. 1 on the fuel pump and one in<br />line just before the carb. and possibly a water/fuel filter. for me My problem was the fuel<br />pump. I guess the pervious owner was having the problem and added an electric fuel<br />pump. (my relay was going bad) drove me batty for months. What have you checked? <br />Also he added a primer bulb in the fuel line and as it was bogging if I squeezed it was<br />fine. that helped me narrow it down good luck.
 
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chesire

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Re: Merc 140 Fuel System Question ?

sorry I backed up the browser and refreshed
 
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lucey

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Re: Merc 140 Fuel System Question ?

I am going to check the fuel pump over the next couple of days. Other than that i have a carb kit ready to go. So hopefully this will cure the problem. I wonder if fuel sloshing around in the tank might be causing a momentary pause in fuel flow causing this bog ?
 
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torxdrive

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Jul 15, 2002
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Re: Merc 140 Fuel System Question ?

check you timing then cleancarba nd install your kit
 
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