another 2004 3.0 TKS question

[bman440440]

I'm at a loss for what is going on with this engine... It runs great it starts great from a cold start... but here is whats going on... starts great cold... but when warm you have to give it a LOT of throttle (and yes the TKS is turning off no hissing sound) ... and it fires right up... and the other issue is that when you start it a large plume of "carbon??" (it looks like unburned charcoal dust) comes up to the surface from the exhaust weather its cold or warm... to give you some background the carb has been rebuilt by a very reputable marine mechanic and at first for the 1st couple of months (don't know for sure (its in a slip)because we never noticed it before) no "carbon" but from almost day 1 it took a lot of throttle to start from warm... any help from you would be great!!

 

[TurtleTamer]

Sounds like a poor rebuild. Have a look down the barrels of the carb on shutdown and see if it's dripping once the engine is off. Having to start with throttle open, and black exhaust are both signs of running rich, or having fuel in the intake on startup. It's very possible for the engine to otherwise run correctly.

Good reputation or not, marine mechanics, like anyone else, make mistakes. There's also the possibility it was done by "the new guy" in the shop or by someone with less experience under the watchful eye of the reputable mechanic. Either way it shouldn't take throttle like that to start it and it shouldn't smoke either.

 

[bman440440]

Sounds like a poor rebuild. Have a look down the barrels of the carb on shutdown and see if it's dripping once the engine is off. Having to start with throttle open, and black exhaust are both signs of running rich, or having fuel in the intake on startup. It's very possible for the engine to otherwise run correctly.

Good reputation or not, marine mechanics, like anyone else, make mistakes. There's also the possibility it was done by "the new guy" in the shop or by someone with less experience under the watchful eye of the reputable mechanic. Either way it shouldn't take throttle like that to start it and it shouldn't smoke either.

ok will check to see if the carb leaking on shutdown... and to make sure everyone understands... the plume of carbon i'm referring to sits on the water like somebody sprinkled charcoal dust on the water... when I go down there next and check for dripping after shutdown I will grab a pic of the stuff on the water also

 

[swamplynx]

If you are sure the carb rebuild was good (they used the correct spring loaded needle and TKS specific float settings) and you are still getting fuel drip after shutdown, then the fuel pump is probably bad and putting out too much pressure causing the needle in the carb to unseat and flood the engine.

I had a similar hot start issue which took me forever to track down. Insulated fuel lines (vapor lock), rebuilt the carb myself, replaced every filter, then bought a professionally rebuilt carb. Still nothing fixed the hot start issue. Popped a new fuel pump in (with the thick cork spacer), fixed it. No idea on the carbon plume though.

 

[bman440440]

OK finally got down to the boat and got some pic's and checked to see if fuel was dripping after shut off... here are the pic's of the "carbon plume" and no fuel dripping after shutdown

 

[bman440440]

If you are sure the carb rebuild was good (they used the correct spring loaded needle and TKS specific float settings) and you are still getting fuel drip after shutdown, then the fuel pump is probably bad and putting out too much pressure causing the needle in the carb to unseat and flood the engine.

I had a similar hot start issue which took me forever to track down. Insulated fuel lines (vapor lock), rebuilt the carb myself, replaced every filter, then bought a professionally rebuilt carb. Still nothing fixed the hot start issue. Popped a new fuel pump in (with the thick cork spacer), fixed it. No idea on the carbon plume though.

and just to be sure I'm going to take the carb back and have it checked out again... I do agree it seems to me that there is something wrong with the "reputable marine mechanic's" rebuild