carb issue? Help

[BoatingTimbo]

Just bought this boat and when out today to have fun... didn't get far since i can't open it up past harbor idle speed. runs/idles perfectly, especially after i replaced the plugs, fuel filter and changed oil.

It's a 1989 Marlin with OMC 4.3L Cobra IO. double barrel carb.

I'm guessing this engine has automatic choke as there's nothing like my previous boats for manually engaging choke by pushing in on the key when starting.

When i give it a little more throttle to begin moving faster then a few mph it's just immediately bogs down and dies.

does this sound like a choke issue?

 

[Quack Addict]

Re: carb issue? Help

Yes - sounds exactly like a choke issue. Were you chugging black smoke when you tried to open the throttle? If so, that confirms it.

Check your choke with the flame arrestor removed. The choke plate should be closed when the engine is cold and then slowly open with the engine idling on the muffs. After about 30 seconds or so, the choke blade should be standing straight up. If not, adjust the choke pull-off on the starboard side of the carburetor - it's the cylindrical device that hangs off the side of the carburetor and is held snug with 3 small screws. Loosen the screws and adjust until the choke plate is just a little past wide open when the engine is warm. You may need to readjust the choke when the engine cools back down if you overdo it when adjusting it 'hot'.

 

[gdombroski]

Re: carb issue? Help

Quack Addict's plan is a good start. But before you do any adjustment make sure that the two wires to the choke are getting good contact as it's an electric choke. If that doesn't do the job andf it's not opening fully linkage might be sticking and just need a good dosage of carb cleaner on the linkage and inside the choke. If it's still not opening fully then next I would do the adjustment. My 89 OMC's have Holley carbs and the recommended setting is 1 1/2 notches to the left of the center mark on the carb.

runs/idles perfectly

If still no improvement it might be a fuel restriction problem. When you say runs does that mean in neutral it revs up ok but under load bogs down? If so, undewr load requires increased fuel. I would next replace the anti-siphon valve as it might be sticken. It's a $15 aluminum piece where the fuel line connects to the gas tank. I spent a lot of money on other things before I finally hit that and ran great after replacement