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My 8hp Merc ran great last week and won't start this week???

flatbottomman

New member
I'm so confused. My 2011 Mercury 8hp four stroke ran great last week. I took it out today, and it would not even act like it wants to crank. I did, however, have a few things happen between then and now that may, or may not, have caused this. First, earlier in the week, I pulled the boat out of the garage. I had the fuel tank vent closed, and I noticed gas was was running out of the foot. I looked and the gas tank had plumped up nicely. Today, when I put the boat in the water, the transmission was in forward, and I could not get it to shift into neutral. Because of this, it would not pull start. I had to manually rotate the prop by hand and then it shifted into neutral nicely. I checked that gas was flowing through the fuel line from the tank to engine, I also checked to make sure there was a spark. The engine seemed to have compression. The engine did not do anything to seem like it wanted to start.

Does anyone have any ideas?
 
If you say the gas was pouring out the foot . Thefloat maybe stuck for fuel to rush out. Did you check your oil. ? It may be contaminated with gas.
 
If you say the gas was pouring out the foot . Thefloat maybe stuck for fuel to rush out. Did you check your oil. ? It may be contaminated with gas.

I didn’t. Can I remove the float bowl without needing to replace a gasket? If so, I will take it off tomorrow. If not, I’ll have to order the gasket first.

Also, I just looked, and there is some gas pooled in the bottom of the engine cowling.
 
I pulled the dipstick and oil/gas came squirting our. So yep, gas in oil. I drained the oil/gas, refilled it with fresh oil, and it cranked up on the first pull. I let it run for a few minutes and changed the oil again. I think we’re all good now.

Can Ijust leave the fuel tank vent open all the time to prevent this?
 
Disconnect the fuel line from the motor when not in use - easiest way to prevent this on a portable motor that typically has a connector that's easy on, easy off..
 
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