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Tony220

collapsed bulb

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I have a Yamaha 4 stroke 150 HP engine and it seems that whenever the gas tank goes below half the primer ball will collapse. I replaced the bulb before and it happened again. Can anyone tell me what the problem is?

 

I PUT A NEW OIL AND WATER separator,fuel filter and gas filter at the beginning of the season and only used the boat about 12 times this year.

 

Any help will be appreciated.redface.gif

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View Postsounds like it might not be venting properly,The suction is causing the colapse..maybe

 

 

 

X2, check the fuel vent, they get clogged up and can cause all kinds of problems.

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To see if the vent is the cause, run with the gas filler cap open (be careful) if the problem doesn't happen, the vent is clogged or the vent line is blocked. If the problem happens only at speed, in addition to a blocked vent, there could be other obstructions in the fuel line, bad hose, blocked pickup, bad anti-siphon valve, clogged filter etc. Running with the gas cap open should be done first.

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Sounds like a vent issue to me also.Do what Keeler said.

If that doesn't help, check out your anti-siphon valve at the tank, that could be sticking.

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View PostSounds like a vent issue to me also.Do what Keeler said.

If that doesn't help, check out your anti-siphon valve at the tank, that could be sticking.

 

 

Does sound like a vent issue. Keelers advise is spot on. Although this would mainly occur with a full tank. Vapor lock is the term most use. Antisyphon valve is what I was thinking at first as well. Happened to me a week ago. Pulled that stupid thing off and replaced it with a non-check valve fitting and all is good. Usually if its a bad antisyphon it will be consistent as well. Fuel pick up..maybe...Fuel pump...maybe..Will be interesting to hear what the problem is. Good luck and keep us up to date on what you find out

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View PostIf it is not already set up with the bulb on the tank side of the fuel filter, that may help.

 

I also agree that it sounds like a vent problem.

 

 

Regarding the primer bulb, it should be just before the engine and after any fuel filter/water separators.

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View PostI also agree that it sounds like a vent problem.

 

Regarding the primer bulb, it should be just before the engine and after any fuel filter/water separators.

 

I have always put the bulb closest to the engine also. I see no reason why the filter and bulb could not be reversed. Would be helpful if the bulb started breaking down, having the filter after it.

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View PostI have always put the bulb closest to the engine also. I see no reason why the filter and bulb could not be reversed. Would be helpful if the bulb started breaking down, having the filter after it.

 

Interesting thought.

I guess from a fluid flow point of view, both setups work. For my vessel where the filter is in a locker ( bilge), it isn't practical to put the bulb before the filter.

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View PostInteresting thought.

I guess from a fluid flow point of view, both setups work. For my vessel where the filter is in a locker ( bilge), it isn't practical to put the bulb before the filter.

 

Yea, it is a series circuit, and either should work. There are advantages to having the filter closest to the engine - like if any crap flakes off the hose or bulb.

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View PostYea, it is a series circuit, and either should work. There are advantages to having the filter closest to the engine - like if any crap flakes off the hose or bulb.

 

 

I really had to think about this but can't decide if there is an advantage to one or the other config. In the first case where the bulb is after the filter, it is pulling fuel from the filter. In the second case where the bulb is before the filter, it is pushing fuel to the filter. So if there were a leak at the filter, case one would suck air and case two would leak liquid (or blow air). In reality, the bulb is not used in normal running mode so I suppose I should start to think about something elsesmile.gif

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