The quintessential "Collapsing Primer Bulb" thread

[littletunny]

First off, many thanks to Tashasdaddy for your help. I have taken my 91' Evinrude 48 spl from nothing to running.

I took it for its maiden voyage yesterday. I turned the carb adjustment screw 2.75 turns out as Clymer recommended...perfect idle.

It would run for about a minute then would bog down. Carbs have already been cleaned.

I put my hand on the primer bulb and could feel it slowly collapsing. When I would slow down to idle, it would slowly fill back up.

Yes I have an Atwood fuel tank and a Walmart primer bulb and hose. The arrow on the primer bulb is pointing in the correct direction.

However, the motor has always done this even with the OMC tank and hose. I think it may be the fuel pump and may need to be rebuilt.

One final tidbit, I pulled off the fuel pump and inspected the screen. It looker good, however I noticed the fuel pump was missing the gasket that looks like a tire spoke.

I dont know if this plays into it or not.

Thoughts

 

[tashasdaddy]

Re: The quintessential "Collapsing Primer Bulb" thread

that gasket seals the black filter cap to the pump housing. if i'm not mistaken.

if the bulb is collasping, that says the pump is doing it's job, of sucking from the tank. it sure sounds like the vent in the fuel tank is clogged. or the check valve in the ball is sticking, not allowing gas thru. just for the heck of it, change ends with the fuel line. some monkey may have put the bulb together wrong.

 

[HighTrim]

Re: The quintessential "Collapsing Primer Bulb" thread

We're assuming you have the vent open on the tank correct??

 

[littletunny]

Re: The quintessential "Collapsing Primer Bulb" thread

Yes,

The vent is open and the fuel tank and hose are brand new and there is no obstruction at the suction line.

 

[Kymasabe]

Re: The quintessential "Collapsing Primer Bulb" thread

My two cents worth. My primer bulb was doing the same thing. First few times it was the vent on the tank, which is in my fill cap (12 gallon tank, under my console) Turns out my vent was broken and opening the fill cap a little to let some air in would work. Cap was soon replaced and then worked fine.
BUT...a couple of weeks later, condition returned. This time, it was a faulty fuel line connector at the tank, one of those brass connectors that snap together at the tank to connect line to tank..one side (I forget which one) has a check valve in it, it was weak, the connectors were loose and pushed apart only about 1/8th of an inch but was enough to slow/stop fuel flow. I had somehow moved/disturbed the fuel line and caused the connector problem. Replaced the connectors and has been fine since.

If the bulb is collapsing, the fuel pump is working fine, it's sucking the line dry and collapsing the bulb. The problem is from the bulb to the tank.

 

[tashasdaddy]

Re: The quintessential "Collapsing Primer Bulb" thread

agreed, also many fuel connectors look just alike.. look here:

http://shop.easternmarine.com/downloadFiles/quick_connector_app.pdf

 

[littletunny]

Re: The quintessential "Collapsing Primer Bulb" thread

Would it be bad to remove both check valves in the primer bulb?

 

[tashasdaddy]

Re: The quintessential "Collapsing Primer Bulb" thread

it would not pump then.

 

[tmcalavy]

Re: The quintessential "Collapsing Primer Bulb" thread

Borrow or buy another line with bulb and fittings. If that solves the problem, time to double check your fuel rig.

 

[littletunny]

Re: The quintessential "Collapsing Primer Bulb" thread

UPDATE.....

Ran the boat again today.

Opened the vent ALL the way out. I thought I had unscrewed it enough but apparently not.:redface:

Also leave the primer bulb ALONE ie parralell to the deck. When I would hold the bulb in my hand vertically to see if it would collapse, guess what, it would collapse. It likes to be on the deck.

I hope this fixes it. I still need a few more trips to see if it happens again.

Those fuel lines, tanks, and bulbs are very sensitive.

 

[HighTrim]

Re: The quintessential "Collapsing Primer Bulb" thread

UPDATE.....

Ran the boat again today.

Opened the vent ALL the way out. I thought I had unscrewed it enough but apparently not.:redface:

Also leave the primer bulb ALONE ie parralell to the deck. When I would hold the bulb in my hand vertically to see if it would collapse, guess what, it would collapse. It likes to be on the deck.

I hope this fixes it. I still need a few more trips to see if it happens again.

Those fuel lines, tanks, and bulbs are very sensitive.

I have heard enough negative feedback on the Walmart brand bulbs to never buy one myself. For the price difference, buy OEM.