Is my stalling problem this simple?

[Griffish]

I've been trying to figure out why my Johnson 115 stalls at idle for a couple of weeks...also it will only reach 5000 rpms at WOT. I have de-carbed with Seafoam, replaced plugs, adjusted the idle speed on the water. It runs better (smoother), but still stalls occasionally. The carbs were cleaned about 9 months ago. I started over in my mind today and it dawned on me that when I cold start, the fuel bulb never gets hard...it is always kind of "mushy". I remembered though that when I Seafoamed, I disconnected the fuel line from the seperator and stuck the end directly into a small gas tank loaded with gas, oil and seafoam and the bulb got hard with a couple of squeezes. Didn't think much about it at the time. I checked the tank vent (enclosed tank and thru the hull vent), and damned if it is not blocked. The 2 small visible screens are solid looking and green. If this is not THE problem it is a problem I'm sure.

Could this simple problem cause both the stalling and the lack of RPM's at WOT? What is the best way to clean the screens?
Thanks!

 

[geedubcpa]

Re: Is my stalling problem this simple?

I have had similar problems - one simple check and cheap fix - make sure both ends of the pump bulb lines are properly seated and tight - where the fuel line goes into the motor and where the fuel line goes into the gas. If they are loose you lose pressure. Also don't go cheap on the gas bulb itself -on the bigger motors you need a little more pressure, so the bulb itself might work fine on a 9.9, but doesn't have the pressure anymore for a 115.

Just my .02

 

[Griffish]

Re: Is my stalling problem this simple?

Thanks geedubcpa I will double check those connections and may go ahead and replace the bulb just to be safe.

 

[tx1961whaler]

Re: Is my stalling problem this simple?

I have had similar problems - one simple check and cheap fix - make sure both ends of the pump bulb lines are properly seated and tight - where the fuel line goes into the motor and where the fuel line goes into the gas. If they are loose you lose pressure. Also don't go cheap on the gas bulb itself -on the bigger motors you need a little more pressure, so the bulb itself might work fine on a 9.9, but doesn't have the pressure anymore for a 115.

Just my .02

Nice, but there is no pressure in the fuel line from the tank to the fuel pump. The fuel pump sucks the fuel through the line. The primer bulb is only to fill the carbs with gas. A leak in the fittings will cause an air leak into the lines.

To answer the original question, yes, a clogged vent can cause the problems that you have described. Without a means to get air into the tank, the fuel pump won't be able to suck fuel.

 

[geedubcpa]

Re: Is my stalling problem this simple?

Without the initial pressure from the fuel bulb pumping, your boat will never get started properly and also if the fuel bulb goes soft - you will lose fuel to the pump - so whatever you want to call it pressure or suction or whatever- you need a good functioning bulb on the bigger motors vs the smaller motors.

I have had the exact same problems and a new bulb changed the whole outlook. Personally I change my bulb every 1-2 seasons.

My problems also occured at WOT and when I replaced the bulb the problems went away - I also make sure both ends are tight at the fuel pump and the fuel tank so you don't lose suction - pressure or whatever at that point.

I should also say that 2 seasons ago I wasted at least a whole saturday trying to keep my motor running and it was the stupid primer bulb - even though the bulb looked ok - 5 minutes after installing the new bulb and I was 100% on track for the rest of the season.

This year I had similar problems, but noticed the two clamps were not that tight and as soon as I got them snug the motor was running good again.