Author Topic: Excessive Fuel Burn Black Exhaust  (Read 84 times)

Offline trudaddy

  • Newbie
  • *
  • Posts: 2
Excessive Fuel Burn Black Exhaust
« on: August 07, 2025, 09:11:32 AM »
I recently rebuilt my quadrajet and did the initial 2.5 turn tune. I put on muffs. Boat fires up with two pumps and idles around 800 rpm.

Additional work done just in case relevant. I emptied fuel tank, new fuel/water filter, replaced fuel guage sender and all fuel related hoses. Replaced throttle control cables and shift linkages. All set to spec.

There is excessive fuel smell when running in addition to blackish smoke from exhaust. I got a bit of dieseling one time after running 3/4 throttle and and abrupt shutdown. I cannot figure out the issue. I have checked the float with guidance from Cliff. That is not the issue. Not sure what to check/adjust.

Offline 77cruiser

  • Qjet Hero
  • *****
  • Posts: 661
Re: Excessive Fuel Burn Black Exhaust
« Reply #1 on: August 07, 2025, 09:25:01 AM »
Is the issue only at idle?
Jim

Offline trudaddy

  • Newbie
  • *
  • Posts: 2
Re: Excessive Fuel Burn Black Exhaust
« Reply #2 on: August 07, 2025, 01:02:55 PM »
If I start the motor and it just idles it is mostly fine. The problem happens when giving it gas and generally driving the boat as intended. The problem persists when running in gear at low speeds in no wake too. At idle after first starting up it isn't really an issue.