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1998 Yamaha 115hp 2 stroke fuel filter

J

Jacven

New member
Hi guys.

Quick question. I have a issue with my fuel system. I have replace everything up till the small fuel filter just before the fuel pump. Next thing to change is the fuel pump. My question, should the clear bowl on the small filter always be full? I prime it with the fuel bulb and the small clear bowl is full, but it drains to the level of the spring inside with in 30s of starting. I can see fuel occasionally come in to top it up a little with the odd bubble here and there.
 
I would be highly surprised its not the fuel pump. clear bowl is a water separator/filter it should be full and drained on occasion.
 
I replaced the fuel pump diaphragms and gaskets today. At idle it seems drain to just below the filter element but at higher rpm it starts topping it up again. Not sure what else to look at now. C
 
Fuel tank breather shut?, pump sucking air and not fuel (vacuum lock). Air leak in fuel line is unlikely as you replaced that. Something is causing the pump not to work properly or its not able to suck fuel. I would take pump apart again and check diaphragms and gaskets again also check for a blockage in the pump fuel passages.
 
Not sure how check vacuum lock. Didn't pull the whole pump apart. So will do that next. Can length of fuel line be an issue?
 
If you squeeze the bulb does fuel flow easily? Like its not trying to suck the tank sides in. Is it an inboard tank or portable one? Other then that, air leak in the engine so the crank case is not under vacuum causing the fuel pump not to work. Is there a gasket between pump and engine? Is it still good too? Moneys still on fuel pump though. You can check if they work should be a video online. They also have little non return/reed valves inside that could be damaged.
 
Pretty easy to squeeze. 3 pumps and its hard. I replaced the gasket between pump and engine. Think I'm just going replace the whole pump. Will search for the video out of interest sake
 
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