Collapsed Primer bulb

[dutchweel]

My engine is having a problem when trying to idle.

After the motor warms up I can quickly get to high speeds, when I back down he motor quits. When this happens I noticed that the primer bulb was collapsed. The only way to fix the bulb is to disconnect the fuel line from tank and remove the connector. When I do this the bulb goes back to normal.

Does anyone know why this is happening and a way to fix the problem?

 

[sparticus]

Re: Collapsed Primer bulb

I am by NO means an expert but I would have to say that a new primer bulb may be in order. Sounds like its weak and is collapsing.

 

[j_martin]

Re: Collapsed Primer bulb

Either the vent on the tank is not open, or the pickup line in the tank is plugged, or the line between the tank and the bulb is plugged. I've seen a foil seal from an oil bottle in the gas tank get over the pickup screen and cause this in a random way.

Bulb is probably OK unless it feels like a cooked marshmallow in your hand.

hope it helps
John

 

[Texasmark]

Re: Collapsed Primer bulb

Agree with John. You are suffering from fuel starvation and the collapsed bulb says that the fuel pump in the engine is sucking, but can't get any gas so it forms a vacuum in the fuel line which collapses the bulb.

Mark

 

[Silvertip]

Re: Collapsed Primer bulb

Ever try sucking on a plastic soda bottle. The sides cave in don't they! Unless there is a way for air to get into the tank, you can't get fuel out of it. As mentioned, the vent is not open, the pickup tube in the tank is clogged, or there is a restriction between it and the bulb.

 

[thinksun]

Re: Collapsed Primer bulb

99% of time it's the anti-syphon valve. These valves are a check style using spring and ball bearing. The intent by Coast Guard requirements is if your carbs are equal or lower in elevation to fuel tank it stops fuel syphoning. This usually applies to I/O's not an O/B. The problem is at best of times it's restricting fuel flow to your engine and often fail and stick partially closed.

I don't run I/O's and have removed all of mine as soon as I get them. Tank suppliers for boat manufacturers don't know final design or engine that product is going into so they pre-rig them with valve. I have seen several people spend lots of money tuning just to find it is this common problem. The valve is installed after 90 deg fitting on tank and is easily changed or modified by punching out bearing. If you require a valve they come in different sizes and I would install or replace with the largest possible one because 2-strokes need fuel to live.

 

[russelleotero]

Re: Collapsed Primer bulb

i have forgotten to open my fuel tank vent a couple times now, sucked the bulb flat, check your tank, easy to forget when in a hurry.