Mercruiser 140 barely running and running rough

[Alumarine]

I need some help and I'm stumped!
Yesterday cruising at 3700 rpm just fine and rev's started to go down like I was running out of gas.
I brought it down to 1500 rpm and was able to go 1/2 a mile to a dock.
As I approached the dock and brought the throttle back it died.

I'm testing this on land now.
Checked fuel level and had plenty. No water in fuel.
Fuel is getting to carb
I can start it in neutral if I give it lots of throttle and have to keep it at 2000 rpm.
If I try to reduce the throttle below 2000 it will die.

Compression is good. Plugs were black but normally they are a good color.
Well maintained. Ignition components have 30 hours on them.
Rebuilt the carb a few years ago and have put on lots of miles since.
At 2000 rpm it runs rough.
Here's the strange part. If I pull off any plug wire the revs go to 2500???

I've enclosed a picture and fuel is coming out the hole that's circled?
thanks

 

[Bondo]

Rebuilt the carb a few years ago

Ayuh,...... Sounds like it's time to do it again,......

I believe you'll find that, that hole is the bowl vent,.....

 

[Alumarine]

Ayuh,...... Sounds like it's time to do it again,......

I believe you'll find that, that hole is the bowl vent,.....

Thanks Bondo, I'll order a kit.
Would that cause the symptoms I'm having?
What part of the rebuild do you think caused that leak?

 

[Rick Stephens]

Somethings plugged up. Yes, your most likely suspect is a carburetor needing cleaning.

 

[Bondo]

Thanks Bondo, I'll order a kit.
Would that cause the symptoms I'm having?
What part of the rebuild do you think caused that leak?

Ayuh,...... The needle valve is leakin', not stoppin' the fuel pumps flow,....
Probably got plugged passages in the idle/ low speed circuits,.....

 

[Scott06]

Agree with rick and bondo thats the float bowl overflowing, only thing to add is verify the fuel pressure is ok as too much fuel pressure can over come a otherwise ok needle seat and float. Also check condition of float make sure it is not damaged or water logged

 

[Alumarine]

Thanks guys.
Hopefully I can get a merc 823427A 1 kit tomorrow and don't have to settle for a Sierra kit.
Fuel pressure was 5.5 lbs at cranking speed.
Will check float condition.
Apparently I rebuilt it 6 years ago not 3.
Of course today was the last of the good weather. Cool and wet for the next while.

 

[Alumarine]

Problem solved hopefully. It now runs great on muffs.
I guess 6 years ago when rebuilt the carb I didn't tighten the Float Needle Seat enough. It had backed out quite a bit.
I tightened it well, put the carb back together and it runs great.

The water coming out the prop exhaust was very sooty for a minute.
Probably because it was a bit rich!
Not sure if I'll get a chance to test it in the water this year.

Thanks for the help!

 

[Alumarine]

Forgot to mention that I noticed the Quicksilver 823427A1 carb kit is identical to the Sierra 18-7070.
Same packaging, same parts, same instruction sheets.
Only difference was the label and pricing.

I suspect that goes for other mercruiser carb kits as well.