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update Merc 2001 90 HP 4 stroke

Shellbackcva59

New member
This is a follow up to an earlier post. I have a 2001 Merc 90HP four stroke, powerhead made by Yamaha. This motor has been giving me fits on hot restarts. Might start right up, then take off, and it falls flat on it's face. Fuel bulb is soft. I pump it up, and I have to crank and crank WOT to get it to start. Soft bulb makes you think an air leak or weak pump, and no fuel to the carbs. But the having to start WOT leads you to believe it's flooded. Usually the first restart of the day while drift fishing is okay, but as the day wears on, they get progressively harder. Yesterday after I brought it home on the trailer, I happened to check the bulb and it was soft. So I go ahead and pump it up, and fuel starts running out the air box! The fuel is getting past the needle and seat on the float! Now, I replaced the needles and seats and set the float level earlier this year when commissioning for spring, because when I pumped the bulb then fuel ran out. At that time I figured the needles and seats had shellaced over the winter. The carbs are super clean, 1 external fuel/water separator, and 1 under the motor hood. I go out this morning, and pump the bulb, and it's hard and no fuel come out the air box. Now I'm thinking this problem is related to motor temp. After each drift of 20 minutes or so it gets progressively worse starting. I don't think it could be vapor lock or something like that. Almost 2 hours had passed since I pulled the boat and got home, before pumping the bulb and having fuel run out. Yet this morning 14 hours later, the floats won't allow any gas to pass thru. I'm going to do an ultra sonic cleaning on the carbs, but I was wondering if a tech ran into a similar situation? Early on I was figuring my motor was running out of fuel when it quit after restarts. Now I'm lead to believe the motor didn't quit due to lack of fuel, but too much fuel. The soft bulb was the result of no back pressure, just fuel pouring thru the carbs.
 
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