Unburned Fuel Bravo One - 454 Mag 7.4L Carb

[gibbywmu2000]

Hello,

Noticed this for years, never really been a huge deal, more of a curiosity. My '97 Powerquest runs great after its warmed up......but when I start it for the first time after a week or 2, it spits out quite a bit of unburned fuel out of the thru hull exhaust. I've gotten so used to it, then I barely dip the boat in the water on the trailer, so that I can warm it up. It runs perfectly fine after its warmed up for several minutes. I just thought maybe this unburned fuel is someone getting out? That crap clings to my hull and leaves black stuff everywhere, so that has been my only option. I don't think it does it as bad throughout the rest of the weekend, or so I have noticed when I take the boat out on Sunday and clean it off.

Is this just a matter of adjusting the carbs, or is this totally normal and not even something to bother with?

 

[Scott Danforth]

if its leaving black carbon, that is normal when the motor is cold and first warming up. however it may be running a bit rich. pull the plugs and read them.

 

[gibbywmu2000]

Yes thats exactly what it is.......I would call it black carbon. It's more of a nuisance because it gets that nasty stuff all over the hull, it just clings to it. I did change the plugs several years ago, but I"m worried about adjusting the carbs because I have not adjusted the fuel mixture before. I guess its better to run it rich than to run it lean right?

 

[MikDee]

If this is a Quadrajet carb, maybe the core plugs in the float bowl have started leaking, this is a known possible issue on old Q-jets. You would have to take the carb off, and look in that area for any signs of a leak? It can be repaired with a filler that doesn't dissolve in gasoline.