Fuel primer bulb

[Whoopbass]

The fuel primer bulb keeps draining back into the tank. Every time I stop and fish I have to go to the back of the boat and squeeze the bulb firm so I can start the boat. I replaced the bulb with a new one and it does the same thing. The new bulb is an Attwood EPA type and for me to get it to prime I had to mount it vertically. The old bulb worked at any angle and just laid in the splash well of the boat. Anybody have any idea's on what's going on? Thanks

Additional details: 1996 Johnson 115. The fuel tank is built under the floor of the boat.

 

[82rude]

I had to go through 3 different new bulbs before I got one to work .In your case because you have in floor tank I would check out and see if you have an anti-siphon valve that could be the problem .It is probably full of crud or defective.

 

[Whoopbass]

I'm not happy with this new EPA style bulb. It took forever to get it to prime and I wasn't even sure if it was going to work when I took the boat out yesterday. I will locate the anti siphon valve and see what's going on with it. It's probably the issue since both bulbs have identical problems. I assumed since the bulb has a check valve it would always hold whatever amount of gas it has in it once you shut the motor off.

 

[emdsapmgr]

The anti-siphon valve atop the built in fuel tank can also leak. If any debris gets inside the ball (check) valve, fuel will leak right back into the tank.

 

[Whoopbass]

I can't find an anti siphon valve on my fuel tank so I don't think it has one. The barbed fitting on my tank is open with no check valve. The new primer bulb was defective so I had the same symptoms as my old bulb. I thought it was good until I blew into it again and discovered air was slightly passing through it. I hooked up an old bulb I had to it and it appeared not to leak back down into the tank. The only problem is that the barb fittings are 1/4" instead of 3/8" so I can't use that one. I found a NOS primer bulb on ebay that was made before the EPA changed em into junk and bought that so hopefully my problems will go away. Thanks

 

[sutor623]

And probably not a bad idea to install an anti-siphon valve on your tank if it is below deck. That will help with the backwards flow as well as prevent any catastrophic issues if you develop a leak in the fuel line.

 

[F_R]

Those bulbs typically have leaky valves. I wonder, what is the effect of the fuel drainback? It should not be draining out of the carburetors or fuel pump, so the motor should start and run and suck up its own gas from the tank. Also, if everything is air tight it should not drain back anyway.

 

[Whoopbass]

Those bulbs typically have leaky valves. I wonder, what is the effect of the fuel drainback? It should not be draining out of the carburetors or fuel pump, so the motor should start and run and suck up its own gas from the tank. Also, if everything is air tight it should not drain back anyway.

This makes sense. Sounds like I have a problem because it won't start until I pump the bulb and fill the carbs back up with fuel. I was thinking about adding an anti siphon valve but then I thought if it didn't come with one then why add a part that could fail down the road well now I should probably re-think that. Looks like I have some trouble shooting ahead of me. Thanks

 

[thumbnut]

I took apart my primer cause mine would not check 100%. The seal end of both of the checks had a surface like 200 grit sand paper. It was part of the design from the start so some will not check 100%. No idea why...

The fuel pump checks should keep the fuel in the line, especially of they are spring loaded. Maybe a pump rebuild in the future.

 

[Whoopbass]

I think my issue was the fuel pump in the VRO. A while back I noticed it would weep gas out of this round cap on the top of the plastic body of the pump. I completely forgot about this until today. I don't know what this cap is for because it doesn't pop off or do anything. I ended up putting 2 part epoxy over it to stop it from leaking so hopefully everything is air tight now. I rebuilt the carbs as well and it fires up and runs perfect. Well, it has always ran pretty good on the muffs, put it in the lake and it fires up pretty easy but after a run it's hard to start because it slightly floods itself. I have to fast idle it to get it started nearly every time unless i'm stopped for about an hour. Hopefully this issue will be cleared up as well. Thanks for the help