Bogging Down

[bryanredfish]

My 2002 Merc 90 (carb'd and 2 stroke) has a strange habit of bogging down at the very first acceleration of the day. It's like it's starving for gas, or is taking a few seconds (5-10) to get the suction built up. Gas lines are new - no leaks. Fuel/Water separator is fine. Basically, I'm sure there are no leaks. Fuel vent line is clear. <br /><br />What's strange is it only happens at the very first acceleration -- never again throughout the day. Runs fantastic otherwise. Is it possible it's just taking a moment to get the air from the system? Thanks much for the input.

 

[bryanredfish]

Re: Bogging Down

Also, the bulb is firm when pumped up, and doesn't appear to be collapsing.

 

[Bob Kimber]

Re: Bogging Down

Hi Bryanredfish,<br /><br />My 90 Merc (2000 model) does the same thing, I was putting it down to the fact that I have to run at 6 knots from the ramp for about 1/2 mile on a cold engine before I can open it up. I have checked all fuel associated items and sync & link, everything checks out fine. I have heard that these motors are overcooled and sometimes require a higher setting thermostat change in cold areas. The bog is gone as soon as it gets on the plane and even if you only go a 100 yards and open it up again, it is perfect and runs well the rest of the day whether hot or cold starts, I felt like it may be loading up more than starving for fuel.<br />Bob

 

[bryanredfish]

Re: Bogging Down

Boating Bob, <br /><br />That describes my problem exactly. I guess I'll not worry about it, since it runs great otherwise. Also, I have noticed that it takes FOREVER for this thing to get warm. I've let it run in my driveway (on hose) for 30 minutes, and the pee-stream is hardly lukewarm. Thanks much for the response. I guess I'll turn off the "panic button."

 

[jim dozier]

Re: Bogging Down

What you are describing is a lean carb condition at the mid-range jet. The fact that it only happens when the engine is cold is consistent with that. Cold engines require a richer mixture than warmed up to operating temp engines, that's why we choke them when they are cold. The answer may be to run it on part choke until warmed up or to warm it up longer, or it may be that you are on the edge of needing a carb rebuild and your carbs jets are partially gummed up with crud and its only apparent when the engine is cold. You might be able to forestall the carb rebuild a little longer by richening the idle by unscrewing the idle adjustment, if it has one, a 1/4 turn.