Primer feeding idle?

I posted this same issue about 4 years ago. Still battling it and hoping for some new ideas. I have a 1988 electric start/ electric primer Johnson 20HP.

The slow idle mixture screw has no effect on achieving a smooth idle. At idle, there was a constant flow of gas bubbles through the primer lines to the carburetor. I put clear lines on the primer so I can see it happening. It idles, but not smoothly, and as I said, I can be a 1/4 turn out from seat, or 10 turns out from seat and there is no change to the idle.

Is it possible that the bubbles of gas are providing enough gas to fuel idle? Why is this happening? IS it possible that I don't have the primers lines connected correctly? Can it be a faulty primer? I tried rebuilding it (did not put in new springs) but this issue remained.

Does anyone have a diagram of how the primer lines are supposed to be connected?

THanks!

Emil

The bigger hose on the PRIMER VALVE gets fuel pressure from the fuel pump.-----The 2 small hoses feed fuel to the intake manifold.----The fuel from the primer valve bypasses the metering circuits in the carburetor.

Thanks for the reply Racerone.

I've searched the forum and found entries that talk about the primer line routings. I believe I have them correct. Looking at the primer from the rear of the engine, there are two small nipples. The left nipple has a single hose which is attached to the nipple behind the fuel pump. The right nipple is attached to a T which has one line going to the top of the carb, and the other line going to a nipple below the carb.

If the routing is correct, I believe the issue is that i am getting some gas flow to the carb when the key is not engaged. Maybe a weak spring in the primer and so the plunger isn't firmly seating against the gasket?

Any other thoughts on why the low idle mixture screw is having no effect on the idle?

Simple ---just remove the 2 wee hoses , after the motor has started.-----If fuel comes out then you have to repair this primer valve.

Played with the boat this weekend.

I pulled the two lines off the primer. Using the primer line T, I had the 3 primer (recirculation) nipples connected; above the carb, below the carb, and behind the fuel pump.

There was fuel flowing from the nipple below the carb, to the nipple above the carb. (I would say it was more like bubbles flowing).

I also noticed that I have a smooth low idle (750 RPM), but that I start getting sneezes from 1300-1700. Once I am 1800 and over, it runs smooth again.

I also notice that there seems to be fuel collecting in the throat of the carb.

Could this be that the float is not closing off the fuel when the bowl is full? And that low RPM isn't pushing too much fuel (750RPM), but at 1300-1700 the pump is pushing more fuel than the carb can handle, and then at 1800 and above the engine is consuming everything that the pump can provide?

Also thinking that at 1300-1700, if the pump is pushing fuel into the engine it is pooling and feeding the primer (recirculation) line below the carb?

I am guessing here, any educated guidance would be much appreciated!

Thanks! Emil

I meant to add that no fuel was coming out of the primer with the 2 primer(recirculation) lines disconnected. I had disconnected the purple wire so that the solenoid wouldn't fire.

How common are vacuum leaks through crankshaft seals, etc? I am wondering if this is the cause of the motor sneezing between 1300-1700?

There are primer lines and a " recirculation " line.----They are separate from each other.-----Serve a different purpose.-----What do you think the recirc line does ?

Racerone,

I understand that the recirculation line brings unused fuel out from the manifold. I guess I am wondering it is an excessive amount, and whether that could be causing the sneezing.

Researching the sneezing, I am now wondering if I have a vacuum leak somewhere?

I have already:

- rebuilt the carb including a cleaning in an ultrasonic bath, link and synch several times
- remounted carb to manifold with a new gasket
- replaced the spark plugs (one step hotter), and new spark plug wires
- replaced the fuel pump
- new fuel lines