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2012 Mercury 9.9HP 4 Stroke won't start.

L

luddite20

New member
Hi wise people-

I just picked up my first 4-stroke, a non-running 2012 Mercury 9.9HP outboard. In trying to get it running today, and before doing anything, I noticed the following:
  1. The compression is fine in both cylinders
  2. the engine would turn over briefly (1 second) if the choke was open and I primed the carb multiple times
  3. when I primed the carb, I saw fuel leaking out of both the inlet connection and the pump on the carb
  4. The pump seems to be working, when I pull the inlet hose from the carb and crank the motor, gas spits out.
  5. The fuel filter looks reasonably clean
So I decided that maybe the`carb was gummed up , and pulled that today to clean it. I installed it back in the engine, and it seemed to help, but the engine still dies after a few seconds. However, it will run, if I prime the carb up to 20 times ( I still see gas leaking out of the pump on the carb when I do this) and then engage the gear into forward and rev the RPMs. If I drop down the rpms then it dies. So again, if I get it running for a second and then flood the engine with more gas, it will run (the weep/exhaust water is not too powerful, so I probably need to replace the impeller as well), but as soon as it idles it dies.

Any suggestions on where to start? Methods to troubleshoot?

Thanks for any help you can provide.

Best,

Chad
 
Carb idle circuits are still jambed up, Needs to be removed,disassembled entirely,soaked overnight,every nook and cranny scrubbed, High pressure water shot thru all internal passages,followed with high pressure dry filtered air, reassembled with a new rebuild kit. Before restarting,flush entire fuel system from inside of tank to carburetor. Fuel pickup in tank ,any filters,entire fuel line,primer bulb and pump assembly for leftover gum
 
Thanks johnnygjr-

I don't have a rebuild kit yet, but I did soak the parts over night. Installed it again, and now it will start and run if I prime the carb, but will turn off as soon as the choke is closed. So I'm assuming it's still running too lean.

I cleaned and blew out all the jets. The plunger looks fine. I've never had so much trouble with a carb before.

johnnygjr said:
Carb idle circuits are still jambed up, Needs to be removed,disassembled entirely,soaked overnight,every nook and cranny scrubbed, High pressure water shot thru all internal passages,followed with high pressure dry filtered air, reassembled with a new rebuild kit. Before restarting,flush entire fuel system from inside of tank to carburetor. Fuel pickup in tank ,any filters,entire fuel line,primer bulb and pump assembly for leftover gum
Click to expand...
 
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