Terry Olson
Chief Petty Officer
- Joined
- Aug 20, 2005
- Messages
- 415
I'm working with limited information about what I suspect is a fuel delivery problem a friend is having with their 4 year old Mariner 40.
Recently the motor quit and a quick check revealed that the primer bulb was collapsed. A check of the tank vent confirmed that it was open. They replaced the primer bulb with a new one and coincidentally added fuel to the tank. When they started the motor and put it to fast idle in nuetral to warm up they noticed that the motor surged gradually with the surge spanning about a 1,000 RPM range. I was able to listen and noted that the surge was gradual, not like you'd expect if the motor were dropping a cylinder or there were some electrical explanation. I had them double check to confirm that the fuel lines were attached properly on both ends and learned that after running the motor and experiencing the surging the primer bulb was still relatively firm.
First, what would make the primer bulb collapse if the tank were properly vented?
Second, is the addition of fuel to the tank a coincidence or is there some explanation for it's being related to the symptoms experienced?
My advice was to try fresh fuel in a different tank to eliminate the current fuel as the source of the problem. Any other ideas?
I know it could be debris in the carb but are these symptoms indicative of a common problem with this motor?
I don't have immediate access to the motor, but any advice would be appreciated.
Thanks.
Recently the motor quit and a quick check revealed that the primer bulb was collapsed. A check of the tank vent confirmed that it was open. They replaced the primer bulb with a new one and coincidentally added fuel to the tank. When they started the motor and put it to fast idle in nuetral to warm up they noticed that the motor surged gradually with the surge spanning about a 1,000 RPM range. I was able to listen and noted that the surge was gradual, not like you'd expect if the motor were dropping a cylinder or there were some electrical explanation. I had them double check to confirm that the fuel lines were attached properly on both ends and learned that after running the motor and experiencing the surging the primer bulb was still relatively firm.
First, what would make the primer bulb collapse if the tank were properly vented?
Second, is the addition of fuel to the tank a coincidence or is there some explanation for it's being related to the symptoms experienced?
My advice was to try fresh fuel in a different tank to eliminate the current fuel as the source of the problem. Any other ideas?
I know it could be debris in the carb but are these symptoms indicative of a common problem with this motor?
I don't have immediate access to the motor, but any advice would be appreciated.
Thanks.