Announcement

Collapse
No announcement yet.

Too rich gas mixture?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Fuel System: Too rich gas mixture?

    I've been told by at least one person that the mixture's too rich on my Sky Hawk, and also you can smell gas when it's in the garage and the mileage is way down. The car starts and runs great and I'm afraid if i take it to my mechanic he'll make it too lean and it'll stumble and stall dangerously. Suggestions?
    peter lee

  • #2
    I'd personally be inclined to look for leaks or fuel boiling out of the float bowl before I'd condemn the a/f mixture. As a thought, pull a couple of spark plugs and look at the electrodes. Unless there is a bunch of flaky carbon on them, I'd probably just keep driving it. Reading the plugs can help a lot with these type issues.

    Bob

    Comment


    • #3
      Sooty Exhaust? Smoking blackish? Like Bob Said, read the plugs. If you're smelling fuel, it's most likely a leak, or fuel boiling out.
      Dumb question: when your engine was rebuilt, did you replace the fuel pump?

      Comment


      • #4
        Excessive rich mixture is usually related to the float, either too high or it is gas logged and not floating.

        Comment


        • #5
          From your description, I would say evaporation and/or leakage and not a too rich mixture.
          A lot of these new "mechanics" do not understand that the exhaust from an older car (pre-1975) is not like that from a newer car.
          Gary L.
          Wappinger, NY

          SDC member since 1968
          Studebaker enthusiast much longer

          Comment


          • #6
            Originally posted by plee4139 View Post
            I'm afraid if i take it to my mechanic he'll make it too lean and it'll stumble and stall dangerously. Suggestions?
            There really is no way a mechanic can make it run leaner unless he changes jets...and that probably isn't going to happen. You can make the IDLE leaner with the air bleed screws, but that isn't going to affect fuel mileage or fuel smell. If it is running rich the choke is probably not adjusted correctly or is sticking, or the float level is too high. I agree that the fuel smell is likely a leak.

            Unfortunately it is getting tougher and tougher to find a mechanic that is competent with these older cars. If you can't (or don't want to) work on it yourself, it may not be the right hobby for you.
            Dick Steinkamp
            Bellingham, WA

            Comment


            • #7
              Today's fuels just react differently then fuels of the past. If you take your car out for a run, bring it home, drive it into the garage and shut it down, you are as likely as not going to experience the smell of unburned fuel. This is because unlike the fuels of the past, today's fuels will tend to boil off quickly (evaporate) and leave a lingering smell in the air. It doesn't mean that your car is not running right, it's just a fact of life. In and of itself it doesn't mean that the car is't running right, but that doesn't preclude the possibility of other problems.

              Comment


              • #8
                I turned screws on carburetors for fifty years before I got my first Air-Fuel ratio meter and a wide-band O2 sensor. Then, I learned how much I didn't know about what was going on in there.

                Setting idle A/F is easy. Setting cruise A/F ratio is easy. Wide Open Throttle A/F is easy. What is really difficult and expensive to get correct are the deceleration, all the transitions from idle to cruise, from cruise to WOT.

                Just getting all four butterflies to return to exactly the same position every time is difficult; the necessary spring is too strong for comfortable cruise foot pressure.

                jack vines
                PackardV8

                Comment


                • #9
                  Could also be a leak in the fuel sending gasket. They don't last forever. Of course, that would only affect mileage through loss.

                  Comment


                  • #10
                    My money is on fuel boil off. Ethanol is the culprit. I run ethanol free gasoline and it has eliminated all sorts of fuel related problems...

                    Comment


                    • #11
                      Originally posted by 345 DeSoto View Post
                      My money is on fuel boil off. Ethanol is the culprit. I run ethanol free gasoline and it has eliminated all sorts of fuel related problems...
                      I run E10 in all my collector cars. All are carburetored No gas smell. I don't think ethanol is the culprit.
                      Dick Steinkamp
                      Bellingham, WA

                      Comment


                      • #12
                        Smell could be coming from leaking gasket at fuel sender.

                        Comment


                        • #13
                          Also keep in mind these old cars vented to tank to the outside air and if in a tight space you will sometimes notice a slight gas smell from that.

                          Comment


                          • #14
                            I saw some gas stains on the side of the carb and wiped them clean and am keeping an eye one them. I also tightened some screws on the top. In the meantime I checked the tire pressures and they were very low, about twenty pounds! I refilled them all up to 35 (they're radials, of course) and i should see the mileage go back up to its normal 15mpg. These are easy fixes for people like me who love old cars but are strictly from the "Wash 'n Wax" school of maintenance.
                            peter lee

                            Comment


                            • #15
                              Originally posted by plee4139 View Post
                              I saw some gas stains on the side of the carb and wiped them clean and am keeping an eye one them. I also tightened some screws on the top. In the meantime I checked the tire pressures and they were very low, about twenty pounds! I refilled them all up to 35 (they're radials, of course) and i should see the mileage go back up to its normal 15mpg. These are easy fixes for people like me who love old cars but are strictly from the "Wash 'n Wax" school of maintenance.
                              Nothing wrong with your "school of maintenance" 'Cept unless you become curious enough to obtain the manuals, study them, and get familiar with the information and mechanical procedures...you will be forever subject to the mercy of any mechanic who claims he knows what he's doing regardless of his actual skill and knowledge.

                              Originally posted by PackardV8 View Post
                              I turned screws on carburetors for fifty years before I got my first Air-Fuel ratio meter and a wide-band O2 sensor. Then, I learned how much I didn't know about what was going on in there...jack vines
                              Jack, I hope I am not overstating your importance to the forum and the information you provide by putting you on a pedestal and giving you more credit than you deserve, but I do hold your postings in high regard. As far as I know, we have never met but my impression is that you have earned your living wrenching and in many ways that takes a special skill and knowledge base very similar to that of a surgeon to get it right. So for that, you have my respect.

                              That said...I would like your opinion regarding the possibility of misadjusted valves on our engines??? So many of our "mechanics" today work on mostly hydraulic valve engines and are familiar with the quietness of their operation. I wonder how tempting it is to attempt to achieve the same quietness of hydraulic valved engines by "tweaking" the lifter adjusters "just a little more," and causing the symptoms Peter Lee is describing with his engine? It seems to me that a solid lifter type engine with the valves not closing long enough to burn clean will always emit a lingering fuel odor from poorly burned fuel dumped into the exhaust?

                              Coming from me, it's like Gomer Pyle discussing physics...but I would like to know your experience regarding the possibility that this could be the issue with Peter's engine?
                              John Clary
                              Greer, SC

                              SDC member since 1975

                              Comment

                              Working...
                              X