Mercruiser 140 - no power on cyl. 3 & 4

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  #1  
Old 07-20-04, 01:03 PM
Desert Toad
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Unhappy Mercruiser 140 - no power on cyl. 3 & 4

I have a 1973 Mercruiser 140 3.0L and have been fixing and using it for about 5 years now. My latest problem: I had it out a couple of weeks ago and ran fine for several hours, then had a slight miss, so I brought it home and found rotor and cap pretty burned so I replaced them and put in new plugs - the number 1 plug had a bent tip, thought that might have caused resistance and burned the cap and rotor. Now I have no power from 3 & 4 when I remove the wires at an idle. And I have checked for spark and it's good. Shall I check the carb, or maybe the valves, and help would be greatly appreciated. It was running great just a week ago....

Jim
 
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  #2  
Old 07-21-04, 05:00 AM
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Originally Posted by Desert Toad
I have a 1973 Mercruiser 140 3.0L and have been fixing and using it for about 5 years now. My latest problem: I had it out a couple of weeks ago and ran fine for several hours, then had a slight miss, so I brought it home and found rotor and cap pretty burned so I replaced them and put in new plugs - the number 1 plug had a bent tip, thought that might have caused resistance and burned the cap and rotor. Now I have no power from 3 & 4 when I remove the wires at an idle. And I have checked for spark and it's good. Shall I check the carb, or maybe the valves, and help would be greatly appreciated. It was running great just a week ago....

Jim
what do u mean u have no power on 3 & 4 when u remove the wires?
 
  #3  
Old 07-21-04, 06:34 PM
Desert Toad
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I just pull the plug wires off while it's at an idle and listen for a drop in RPM. Played with it a bit today and think it might be carb problem. When I unscrew the forward needle on the carb it bogs down and dies, but when I unscrew the back needle it doesn't make a change until It's clear out, and then the RPM really picks ups. Must be something dirty in there somewhere, I just hope I can clean it out without removing the carb again. Looking at the intake, the front needle is for the forward barrell on cylinders 1 & 2 and the back needle is for 3 & 4.

any help is much appreciated!

Jim
 
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