merc 135 fuel starvation

[mulacek]

I have a 1988 merc v135 v6. I am experiencing a loss of about 1000 rpms and loss of power. It happened suddenly like a switch was flicked. All electronics check ok. Have rebuilt carbs, fuel pump, new primer bulb. <br /><br />When running the motor, it seems as though the lower right half (when looking back at it from the boat) carb it starving for fuel. Rpms instantly jump back an power kicks in when spraying fuel in this carb. This carb is this last one to receive fuel from the fuel pump. You can also notice a fuel spray pattern on the other carbs but not this one when under low power. BTW compression is good on all cylinders.<br /><br />I'm at a loss.

 

[WillyBWright]

Re: merc 135 fuel starvation

Carb needs a rebuild, or there's a bad reed. I doubt it's the fuel pump...all three carbs would starve.

 

[achris]

Re: merc 135 fuel starvation

If you hold your hand close to the carb throats, can you feel any 'blowback'? This would indicate a reed. It does sound like that carb needs pulling off again and re-checking, and check the fuel lines. I've seen blocked lines too.<br /><br />Chris............

 

[mulacek]

Re: merc 135 fuel starvation

I've checked the reeds and they are fine.<br /><br />I bumped the float up a little more and it is now fueling the cylinder about 60% of the time (judging by how it runs). I'm sure the float is set too high right now, though.<br /><br /> I'm wondering if it could mean a vacuum leak maybe around the throttle bore or????

 

[jim dozier]

Re: merc 135 fuel starvation

Have you done a thorough cleaning/rebuild on that carb? By thorough I mean cleaning ALL of the orifices and jets with carb cleaner AND compressed air, and installation of the rebuild kit parts. I'm betting that you still have crud in an orifice somewhere. Its not a beauty contest, it doesn't matter how clean the outside of the carb is. You can't see most of the places where crud can affect flow so clean them all properly.