90 hp force trouble

This is the 3rd time this has happen with a 1990 Force 90 hp. I rebuilt the fuel pump 2 years ago and changed the water pump. I bought a new 6.5 gallon gas tank and added ?sea foam?. When I first go out it runs great for about 20 minutes, when I power down it stalls. It?s hard to start after that, and when it does it will barely move. When I try to give it more gas it will stall. I tried changing the spark plugs but it made no difference. The last time after moving at a crawl for about an hour the battery went dead and it is new. Any suggestions.

I replaced the gas tank before the last time I went out. After about 20 mins. it happened again. I changed the plugs on the lake, and it made no difference. The plugs or the motor didn't seem to be that hot. The water pump seems to be working good. This is the first time the battery went dead.
I let it set for an hour while I fished and it still would only crawl.

Re: 90 hp force trouble

Third time what has happened, JDC?

What you did 2 years ago has nothing to do with the symptoms you are getting now.

Sounds to me like a temperature related failure in the ignition/charging system.

Re: 90 hp force trouble

I talked to a large outboard repair place guy states he would change out his fuel pump diaphram every year! For $13 and hour of your time its no biggy. I went so far to use rtv around gaskets and such. I added some really old 90ish quicksilver octane tune and had the stalling at lake once i reprimed the bulb she ran like a raped goose. I ordered my part should be here monday. Wish we could figure a way to increase our fuel pump presure? Would adding more pump bulbs help out like two in line?