Why is my bulb in my fuel line collapsing

[usmc42000]

I have a 115 johnson outboard. It's running fine but the bulb in the fuel line is collapsing while it runs and never gets tight when you pump it. I just replaced the line and bulb.

 

[iwombat]

Re: Why is my bulb in my fuel line collapsing

You either have a restriction somewhere between tank and bulb, or a plugged vent line.

 

[usmc42000]

Re: Why is my bulb in my fuel line collapsing

Could it be the fuel filter?

 

[iwombat]

Re: Why is my bulb in my fuel line collapsing

Could be a clogged up filter, or an anti-siphon valve.

 

[usmc42000]

Re: Why is my bulb in my fuel line collapsing

I ran it with the gas cap off to eliminate a vent problem and bypassed the fuel filter to eliminate that. The bulb still collapsed. Haven't checked the fuel line between the tank and the bulb. Looks like is going to be really difficult to access. Haven't looked into the anti-siphon valve either.

 

[LongLine]

Re: Why is my bulb in my fuel line collapsing

Bulb got a arrow on it?

Not trying to be a wise guy - Just that I did it once :redface:

Tom B.
(LongLine)

 

[ezeke]

Re: Why is my bulb in my fuel line collapsing

The anti-siphon valve prevents the fuel from being siphoned out of the tank if there is leak in the fuel system between the tank and the engine.

If you can siphon fuel from the tank to the ground through the anti-siphon valve, the problem is probably not the anti-siphon valve.

A lot of aftermarket primer bulbs have defective valves and some of the OEM ones do as well, so try another hose and bulb before anything else.

 

[usmc42000]

Re: Why is my bulb in my fuel line collapsing

Bulb got a arrow on it?

Not trying to be a wise guy - Just that I did it once :redface:

Tom B.
(LongLine)

The arrow is pointing in the direction of the fuel flow from the tank to the motor. I assume that is the correct way.

 

[usmc42000]

Re: Why is my bulb in my fuel line collapsing

I took the boat out to the lake earlier and ran in it a little. It seems to run about half speed with the bulb collapsed but if you pump the bulb while its running it will run fine at full speed.

 

[ezeke]

Re: Why is my bulb in my fuel line collapsing

As others have said, it is still either the bulb or something in the fuel system before the bulb and not after the bulb.

The fuel pickup is a screen at the bottom of the tank on most systems; if that gets gunked up it will cause your symptoms.

Have you changed the cartridge in the fuel filter?

Are you using at least 5/16 fuel line?

.

 

[usmc42000]

Re: Why is my bulb in my fuel line collapsing

I want to check out the fuel tank and the line before the bulb but it seems impossible to get to. I have taken off all of the small access panels but can't see anything.

 

[Mas]

Re: Why is my bulb in my fuel line collapsing

Someone posted this link on fuel lines/bulbs/tanks. It's pretty good:

http://continuouswave.com/whaler/reference/primer.html

MAS

 

[Fl_Richard]

Re: Why is my bulb in my fuel line collapsing

I've had luck with reversing the bulb and putting the engine side fuel line in a tank of gas. Pumping the bulb will either have pressure on it indicating a fuel restriction or it may even force off the contamination on the inlet screen in the tank. If it's the inlet screen then it will clog up again soon but at least you will know the problem.

Not sure if the anti-siphon valve has any affect when doing this. it didnt for me. But it was a small tank in a small boat.

 

[usmc42000]

Re: Why is my bulb in my fuel line collapsing

Update...This weekend, I replaced the anti-siphon valve and the fuel line going from the tank to the water seperator. The bulb is no longer collapsing. I still have the problem with the motor running sluggish. The fuel bulb doesn't collapse but doesn't get firm at all. The boat usually runs around 45mph. Right now it will only run about 30mph. If you pump the fuel bulb while it's running, it will pick it from 30mph to the usual top speed of 45mph. I am thinking now that I may have a problem with my fuel pump.

 

[HybridMX6]

Re: Why is my bulb in my fuel line collapsing

Have you tried again to check the fuel pick up in the tank? A collapsed primer bulb doesn't sounds like a bad fuel pump to me, sounds like a healthy one if it's sucking hard enough to do that. Sounds like it's somewhere before the primer bulb. I know you said it doesn't collapse anymore, just still sounds like the problem is before the bulb.

 

[ezeke]

Re: Why is my bulb in my fuel line collapsing

The fuel pump does not push fuel into the engine, it only fills the float bowls so that the engine has a reservoir from which to pull fuel through the carburetors.

When squeezing the primer bulb on a running engine helps acceleration, it indicates that the float bowls are running low on fuel. That could be because of a weak or failing fuel pump.