1980 9.8, check valve problem?>?

[gayle23]

I have a 1980 9.8 hp mercury. It starts fine but after a short time stalls. If I disconnect the fuel tank connector and wait awhile it will start, and then stall again. The carburetor has been professionally rebuilt 2X. The fuel tank is venting fine. I am thinking this is a vacume problem and the check valve at the engine block is malfunctioning. I removed it and can blow towards the carburetor but not the other way around. It seems to me there should be a vacume from the carbuteror which would assist in sucking gas from the fuel tank into the carburetor. Is that right? should I replace the check valve?

 

[Laddies]

Re: 1980 9.8, check valve problem?>?

That's the way that a fuel pomp works it must have checks they force the pulse that the pump generate to cause the fuel to flow to the carb. If the engine is flooding so bad it requires the fuel line to be removed to get it started you have either a inlet needle thats leaking or a fuel pump diaphragm with a pin hole in it.

 

[gayle23]

Re: 1980 9.8, check valve problem?>?

The check valve I am talking about is not in the fuel pump area of the carburetor (even though there are also check valves there) but the check valve screwed into the engine block, which is connected to the carburetor by a hose. I think the part number is 42863. This valve should only act in one direction and I am thinking it should allow a vacume from the carburetor which would assist in drawing gas from the fuel tank. This is caused by the vacume created when the piston moves up. Your diagnosis may be the problem but is it possible this check valve I am talking about could also be the cause of the problem?? Thanks much.

 

[Laddies]

Re: 1980 9.8, check valve problem?>?

If your talking about item 8 it's just a check valve that regulates the flow of excess oil in the crankcase and it would have nothing to do with your problem. http://www.mercruiserparts.com/Show...97&bnbr=80&bdesc=CYLINDER+BLOCK+AND+CRANKCASE

 

[gayle23]

Re: 1980 9.8, check valve problem?>?

o-k. thanks. I will rebuild the carb, replace the inlet needle, and also rebuild the fuel pump portion of the carb.

 

[bullbat]

Re: 1980 9.8, check valve problem?>?

i would also get a new fuel fitting you could be sucking air around the fuel line