# Primer Bulb



## Brett (Jul 16, 2008)

You've got an air leak in your fuel supply feed
between the tank and connection to the fuel pump.


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## --AL-- (Nov 28, 2012)

REPLACE THE BULB.

I just went through this, fuel bulbs are not made equal. Spend the money on a good brand like yamaha. Look at the pic, the good one is on the left.








If that doesn't work then go look for that air leak. Out of all the technical advice given to me, nobody told me to change the bulb. Solved the problem.


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## Brett (Jul 16, 2008)

I usually just grab a spare tank and hose,
unhook the one causing problems,
hook up the spare and go for a test run.
Air leaks usually occur at the o-rings in the connectors,
cracks in the primer ball, wear on the plastic connectors,
and hose deterioration due to ozone and sunlight.
Hose clamp failures do occur, but not often.


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## Marshfly (Nov 4, 2012)

Yep. Get a new bulb. I bought a brand new Moehler fuel hose for a portable tank a while back. It was bad out of the box. I stopped by the Yamaha dealer and bought their branded one and it was immediately evident to be of much higher quality. Was it double the price? Yes. Was it worth the extra $25? Absolutely.


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## steve77777 (Nov 12, 2013)

yes i just posted the same type of problem and havent fixed it either ,if you fix your please let me know what it was? thx


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## Bridgette1 (Nov 9, 2013)

I was having a fuel starvation problems while running as well. Motor would bog down as if it is running out of fuel. I would grab the primer bulb give it a few squeezes and it would run fine again for about 3 minutes then repeat. I replaced the primer bulb and still had the the same symptoms. I then removed the anti syphon valve problem solved, motor has run like a champ every since doing away with the anti syphon valve.


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## steve77777 (Nov 12, 2013)

what the ------ is a anti syphon valve?


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## cutrunner (Jun 8, 2010)

If you have a built in fuel tank it is the nipple fitting for the fuel hose that goes to the engine. It looks like a normal fittingbut inside is a checkvalve ball and spring


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## cutrunner (Jun 8, 2010)

Answer courtesy of Cutrunnerpedia


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## steve77777 (Nov 12, 2013)

i have a 2003 40hp merc how do you know if you have a built in fuel tank? i would guess look for it -lol,or is it noticeable im asking?


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## Bridgette1 (Nov 9, 2013)

> i have a 2003 40hp merc how do you know if you have a built in fuel tank? i would guess look for it -lol,or is it noticeable im asking?


Your skiffs built in fuel tank. It is the barbed fitting that the fuel line is attached to coming out of the top of the fuel tank.


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## Creek Runner (Sep 1, 2011)

> i have a 2003 40hp merc how do you know if you have a built in fuel tank? i would guess look for it -lol,or is it noticeable im asking?


I'm not trying to be a jerk, but if you have to ask that question you should probably take your engine in for any kind of service needed. Not saying not to ask questions and try to do things your self, and learn as much as you can but if your asking how to know if you have a built in fuel tank your a long ways off. 

A built in fuel tank is a tank that is not portable (portable think red gas can), and usually is going to be under a deck or sub floor of your hull. The barb fitting that comes out of the tank which is hooked to your pick up, has a check valve which is called the anti-siphon valve.


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## steve77777 (Nov 12, 2013)

no i thought maybe an engine had a resevoir at the engine that maybe held some gas thats what i was thinking you could have mint,anyway i have a built in 12 gallon tank and it has a one inch square looks like an aluminum piece coming straight out of the tank where the gas line is hooked to,i would assume that is the anti syphon valve? so if my primer bulb is good and no leaks in line then your saying that theres a ball in the syphon valve that goes bad? is that in most fixtures coming out of fuel tanks? and yes i thought that piece was just a connection from the tank so you could hook up a hose to it and i thought it didnt have a ball in it so thankyou ..


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## Bridgette1 (Nov 9, 2013)

> no i thought maybe an engine had a resevoir at the engine that maybe held some gas thats what i was thinking you could have mint,anyway i have a built in 12 gallon tank and it has a one inch square looks like an aluminum piece coming straight out of the tank where the gas line is hooked to,i would assume that is the anti syphon valve? so if my primer bulb is good and no leaks in line then your saying that theres a ball in the syphon valve that goes bad? is that in most fixtures coming out of fuel tanks? and yes i thought that piece was just a connection from the tank so you could hook up a hose to it and i thought it didnt have a ball in it so thankyou ..


Not necessarily saying that is the problem. I was just explaining the symptoms my engine was having. And with the help of this forum I narrowed my problem down to the anti syphon valve. If your motors symptoms sound like mine it could very we'll be the anti syphon valve is bad. Also I removed mine only because the fuel line never dips below the top of the tank at any point between the tank and the motor. Do some research before you decide to just remove yours. It is there for safety, you need to understand what it does as well as the potential risk of not having it.  Do a little research, Google is your friend you might find that you would rather replace it than do away with it.


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## steve77777 (Nov 12, 2013)

ya i would replace not do away with it,thx..mine only cuts out and stalls like every half hour maybe hour and when it does the ball is soft and its starving for fuel but if i notice that its starving for gas as in puttering out then i pump the ball quick and its good for another 30 minutes or so...


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## steve77777 (Nov 12, 2013)

ok i just posted the same thing on where it says 40 merc but im not sure if you guys will see that post so I will write it once again,Today I took the boat out ,I changed the bulb and the boat stalled every ten minutes at 1,500 rpms again while idling through no wake zones,i guess im in process of elimination now,next i was going to bypass the fuel seperator then go to the anti syphon valve if it really has one...this is frustrating trying to have a romantic night on the water and you gotta pump a bulb-lol,joke but not really it did happen i took my fiance out,anyways please help with any feedback in the mean time i will be eliminating possibilities


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## steve77777 (Nov 12, 2013)

my problem was the fuel pump diaphragm not seating while in lower rpms and seating when in higher,,so it ran good and didnt stall at higher speeds but stalled while in lower,, easiest diagnostic thing was to bypass everything with another fuel tank and bulb then when it still did it then i knew it was from the motor area, ALLL FIIXXXXX THINK GOODNESS


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