Page 2 of 2
Re: Gas in Exhaust
Posted: September 12th, 2022, 11:33 am
by hinzee623
UPDATE: So took a dive into the carb. It appears to be running really rich in of the tubes. A marina friend suggested starting with a rebuild of the carb. Its a Rochester QuadraJet. If anyone is familar with model numbers please let me know.
Its a merc454 340hp engine
Re: Gas in Exhaust
Posted: September 12th, 2022, 11:38 am
by bud37
Have a quick read, maybe something here for you as well....
https://www.carburetor-blog.com/knowled ... eshooting/
Re: Gas in Exhaust
Posted: September 12th, 2022, 1:25 pm
by km1125
Quirky cold starts would also be a motivator to check the operation of the choke system.
Re: Gas in Exhaust
Posted: September 12th, 2022, 1:41 pm
by hinzee623
No ignition Tune up in my time (2 seasons). I did check the cap. Looks good. No corrosion.
Update: looks like its running really rich. It appears too much fuel is getting into the barrel. So going to do a carb rebuild tomorrow. Hopefully this will do the trick. Stay tuned.
Open to other theories as well. Appreciate the input thus far!
Re: Gas in Exhaust
Posted: September 12th, 2022, 5:12 pm
by RobGunn
hinzee623 wrote:QR_BBPOST RobGunn - As a follow up question, prior to discovering this issue. Did you notice that particular engine was a little more difficult to start up cold? Like you have to give it a few pumps of the throttle for it to turn over?
For me, my port engine turns over relatively easy, however my starboard (the one in question) it always takes a few tries, and more or less i need to move the throttle as i am turning the key in order for it to catch. So I am now thinking, maybe my fuel pump has been on its way out (unbeknownst to me, until now). I will still test your theory.
I had no issue with stating the engine, just normal 2 pumps and set throttle to around 1/4 and hit the key.
Re: Gas in Exhaust
Posted: September 12th, 2022, 6:56 pm
by tomschauer
If you are not mechanically inclined and know carbs, don't try to rebuild a QJet on your own. Most likely will end up worse than before you started.
Not a ping on you, but QJets are a bit finicky when setting fuel levels and such.
Re: Gas in Exhaust
Posted: September 13th, 2022, 8:45 am
by RobGunn
hinzee623 wrote:QR_BBPOST RobGunn - As a follow up question, prior to discovering this issue. Did you notice that particular engine was a little more difficult to start up cold? Like you have to give it a few pumps of the throttle for it to turn over?
For me, my port engine turns over relatively easy, however my starboard (the one in question) it always takes a few tries, and more or less i need to move the throttle as i am turning the key in order for it to catch. So I am now thinking, maybe my fuel pump has been on its way out (unbeknownst to me, until now). I will still test your theory.
Engines would start and run as normal before and after the issue.
Re: Gas in Exhaust
Posted: September 13th, 2022, 8:49 am
by RobGunn
My engine that had the issue would start and run as normal, just had big time gas smell and then showed low oil pressure due to the oil dilution. The fuel pump was doing its job of sending fuel to the carb but was also sending fuel to the oil pan...
