120 HP mercruiser 153 ci 2.5 L issues

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,428
Okay now what would cause excessive fuel? Maybe just the new carburator I bought off Amazon is junk?
Float and needle and seat are probably hung up or not put together right, also measure fuel pressure. if too high bowl will over flow. When running look down the bore to see if fuel is weeping into bores off boosters at idle.
If plugs are black just getting too much fuel, more advance probably needed to ignite.... Should run near the factory initial timing spec

If you can rebuild a carb you are probably better getting a quality (aka not amazon) rebuild kit and doing it your self. Mike carb parts has good
 

tannergallant123

Seaman Apprentice
Joined
Jun 21, 2023
Messages
30
Okay sounds good thanks. So now back to my drain line from the fuel pump to my carb. Where exactly on the carb would it go?
 

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ScottinAZ

Master Chief Petty Officer
Joined
Jun 25, 2009
Messages
831
Okay sounds good thanks. So now back to my drain line from the fuel pump to my carb. Where exactly on the carb would it go?
The 90 degree fitting on the top of your carb is where the pump drain goes. It’s plainly visible in your first pic
 

tannergallant123

Seaman Apprentice
Joined
Jun 21, 2023
Messages
30
Hey guys. So turns out the condenser on the distributor was no good and the wire running to the coil wasn’t giving enough voltage. Got it out on the water and it ran great now having issues again. Running full speed and all of a sudden it will pretty much shut off or other times sputter quite a bit to the point where it’s not runnable. Any ideas?
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,073
Fuel supply. Did you check the fuel pickups? Try running on a remote tank and see if it changes.
 

tannergallant123

Seaman Apprentice
Joined
Jun 21, 2023
Messages
30
Ya I ran it on a new tank. The fuel lines are all new as well. I thought it can’t be the timing because when it runs it runs smooth. I figured it had to be an issue with the spark due to the fact that it cuts out randomly completely. I thought maybe it would bog if it wasn’t getting enough fuel and it pretty much just sputters or stops completely. Could it be a bad wire going to the coil? My coil is good
 

tannergallant123

Seaman Apprentice
Joined
Jun 21, 2023
Messages
30
Okay ya maybe I’ll buy a new one. We had a bunch of old ones and the one we put in fixed the problem in the driveway and the boat ran great till I got it on the water under load.
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,428
Okay ya maybe I’ll buy a new one. We had a bunch of old ones and the one we put in fixed the problem in the driveway and the boat ran great till I got it on the water under load.
They all run great in the driveway with no load on them. Would try the remote tank and likely a fuel contamination issue .
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,428
Ya I know. Think it’s a good idea to get rid of the points and condenser with electronic ?
i think you probably have other fish to fry first. a properly set up points system is as good as electronic except it needs annual maintenance in terms of cleaning and setting the dwell.
 
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