30hp loads up and dies at low rpm / idle

[atistang]

I think I know what the problem is here, but i have never messed with an outboard and have only owned my first outboard for about a month now.

so the first thing i notice is when i get on my boat (its docked for the summer) i smell gas. It cold starts fine, and so far as far as i can tell it hot starts fine. now when going through no wake zones i notice it surges and occasionally starts to try and stall out. Also when idling in gear it will sputter then die after 30 seconds or so.

I believe its the float causing my problems. am i on the right track with that thought?

and is is possible if it is my float that with the fuel line from the tank pressurized that fuel is running through the carb and out into the water when the engine is off?

one last thing, i notice that even days later if i open the fuel tank cap it is under a lot of pressure, i have read that people say the tank is suppose to be vented? is this my problem?

help!

 

[bonzoscott]

Re: 30hp loads up and dies at low rpm / idle

Definitely could be the problem if the tank is pressurizing. Bouncing around and sun light will pressurize the tank, forcing fuel past the needle seat, flooding the bowl on the carb. There should be a vent on the tank. You don't mention what model 30 HP you have. Some models where prone to "load up" at idle or no-wake speed. You can try lean it out by the adjustment knob when you know you're going to idle speed, then richen back up when cruising. Being new to outboards, I recommend you do much reading and searching here (ay minimum). Buy the factory service manual for you model if you can. Good luck!

 

[atistang]

Re: 30hp loads up and dies at low rpm / idle

Yeah I have found out that there a a lot of different models of just a 30hp johnson. What's different between them? I assume the bare engine is the same, just different drives, carbs, and the such?

I have noticed that I have went through about 2 gallons (estimation) of fuel and I have probably only ran the engine an hour. Is that normal or do you think some of that fuel was pushed out?

The gas tank is exposed to sun for at least 6hrs a day if not more.

 

[gm280]

Re: 30hp loads up and dies at low rpm / idle

You didn't specify what year or model your 30 HP is and there are so many that it is hard to suggest ideas to fix your problem. If the engine is loading up at idle, you can adjust the low idle mixture on most carbs to correct for that. And there really isn't any reason to readjust after your idle periods. That's because as you proceed to mid to high end, there is a different jet circuit for those mixtures and the idle circuit doesn't effect them. I also don't believe you are pushing raw gas through the engine and into the water or it would stop idling very quickly and not after 30 seconds or more. If your tank is not a pressured tank setup, then yes allow the tank to breathe by opening the vent. Otherwise the pressure has to go somewhere... You also could remove the carb and check the float level to verify it is correct. Not a bad idea to install new gaskets and needle and seat while doing the too... JMHO!

 

[atistang]

Re: 30hp loads up and dies at low rpm / idle

Sorry. The engine is a 1990. I'll try and get out today and see if I still have this problem with the tank vented

 

[atistang]

Re: 30hp loads up and dies at low rpm / idle

ok, so the tank is an OMC metal tank, the fuel connection and vent is all one piece. the vent appears to be an automatic vent

i opened the cap and was greeted by a huge relief of air, then i disconnected the fuel line. I then put the cap back on and before i could even grab the tank gas started to run out of the fuel line connector. so i know the vent isnt doing its job. also what started out as 4 gallons of gas last week is now about a 1/4 gallon and i have only ran the engine about an hour.

whats my option with this tank? do the sell vented caps maybe? can i get a new vented connection like it has on it now?

this is what the valve looks like