Fuel Pump Diaphragm ripping???

pevaughn

Recruit
Joined
Jun 2, 2009
Messages
3
First off thanks to all of you for all your posts! After doing much research on this site I was able to resurrect my Force.
Now for my problem for the second year in a row my fuel pump diaphragm has ripped after only 3 weekends. I have no clue what could be causing this problem. Any help would be appreciated. Details on the boat 1987 18' Bayliner Capri with a 125HP Force. The boat sat out of the water for about 5 years before I got it. I have rebuilt the carbs, replaced the spark plugs, rebuilt the fuel pump including replacement of the (3) check valves using Sierra 18-7806-1 Marine Fuel Pump Kit. All new fuel lines including primer bulb. New inline fuel filter. Drained all old gas and flushed tank. Replaced the impeller and lower unit seals. Ran 3 cans of Sea Foam. 17 Pitch prop.
The boat runs about 4500 rpm at WOT that's according to the original tach. Before the diaphragm ripped the boat ran like a champ was able to pull a skier with 5 adults in the boat so no complaints there. Any help is appreciated. Thanks in advance.
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,849
Re: Fuel Pump Diaphragm ripping???

Does it ever backfire?

Does it ever "sneeze" back through the carb?

Thinking the carbs might be just a little lean if it sneezes.

Or the timing is off if it backfires.

Just throwing it out there for consideration.
 

pevaughn

Recruit
Joined
Jun 2, 2009
Messages
3
Re: Fuel Pump Diaphragm ripping???

Thanks for the reply. It hasn't ever back fired but it has "sneezed" occasionally while starting. I'll adjust the carbs a little and see what happens.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: Fuel Pump Diaphragm ripping???

When you replaced the diaphragm, did you replace the gasket UNDER the diaphragm--that is next to the bypass cover with the diaphragm on top of it? Did you burr (**** up the heads) the screws holding in the center valve? If so, did you file off any sharp edges?
 

pevaughn

Recruit
Joined
Jun 2, 2009
Messages
3
Re: Fuel Pump Diaphragm ripping???

Yes I replaced the gasket. I'll have to check the screw heads for sharp edges. The diaphragm this time ripped on the edge. If you look at it there's the large circle and small circle it ripped right on the edge of the large circle.
 

weebieboy

Cadet
Joined
Sep 17, 2006
Messages
7
Re: Fuel Pump Diaphragm ripping???

Another 2 cents by me; I had replaced the diaphragm on one of my twins and had installed the gasket on the wrong side of the diaphragm and the diaphragm ripped , I believe during the first trip out. Just trying to help.
 
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