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fuel delivery problems??? late 70s 120 Merc

G

gmalone88

New member
So, engine runs goon on the muffs. Wont hardly run on the water, however it does idle sometimes. It set for two years. done a complete tune up minus impeller. Seems to not be getting fuel. it starts aand will usually idle until I put it in gear.
 
Running fuel out of one tank only. The system never had a fuel bulb on the line before. So going through the thing and trouble shooting I added a bulb to it. Ran like a new engine in the drive way. Wouldn't hardly run on the water. Bulb pumps up hard then when started it gets soft then dies.
 
Also I might add that the bulb pumps up and then goes soft almost right away. But sometimes it stays firm for a few minutes. As I said before it never had a bulb on it until I recently added one.
 
Sticky, partially blocked anti siphon valve on tank? The valve is that think on the top of the tank that the withdrawal hose connects to... Also... pre 2007ish fuel hoses not ethanol resistant. Interior liner can become soft or dissolve.
 
You should try the motor on another fuel source perhaps a 6 gallon tank with hose and bulb. I keep a setup like this on my 1987 170 Trophy Alumacraft. Its good to have a spare set up besides the under floor tank. Should ever the fuel pump fail, you can get home with raising your tank onto a cooler or something similar and make it a siphon. Ethanol will destroy fuel pump diaphragms and anything made of rubber or rubber composition. My 115 has original fuel components from 1987.
 
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