C3 fuel problem - NCRS Discussion Boards

C3 fuel problem

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  • Steve B.
    Expired
    • September 30, 2002
    • 13

    C3 fuel problem

    I have a 76 L48 coupe that I have had for several years now. The fuel problem started this summer. Several times now the car will start fine run a few seconds and then cut out. Any further attempts to start simply result in the engine cranking but not starting. Spark is present but pumping the gas pedal while looking inside the carburetor shows no fuel dispersed. If I add some gas to the carburetor the car starts immediately, runs a few seconds, and cuts out.

    This is a Rochester Q-jet carb. Since I'm the third or forth owner of the vehicle I don't know if it's the original.

    Troubleshooting steps:
    I removed the fuel line going into the fuel pump and got a strong, steady, clear flow of gas... thus eliminating possible blockage in the fuel tank.

    I removed the gas line at the carb and there was gas present. I dried the gas up, cleaned the connection, and checked the fuel filter (which I replaced several months ago) it all looked good. Reconnected, attempted to start the car again - nothing, removed the fuel line again at the carb and fuel was present. The fuel pump was replaced new when I rebuilt the engine in the spring of 2003 and has maybe 3000 miles of usage.

    At this point it appears that the problem is in the carb. Not being a great mechanic I was hoping to get someone with more experience to confirm my suspicions and possibly offer a solution.

    Final note: The vehicle has always started eventually. The last time I simply pushed it several yards on a flat surface (living in West Virginia there aren't many of those around) to get it out of the way of traffic. I was getting ready to lock it up and call for help when I thought I'd try it one more time... and guess what - it started and ran fine all the way home.

    It's very frustrating because it runs fine when it runs but I've lost a bit confidence in it... which distracts from the pleasure I get driving it.

    Any insight would greatly appreciated, thanks.

    Steve Boyd
  • Jack H.
    Extremely Frequent Poster
    • April 1, 1990
    • 9906

    #2
    Re: C3 fuel problem

    Could be time for a routine carb overhaul. If the needle valve that paces fuel flow into the bowl is sticking closed, you'd have this kind of Jeckyl/Hyde situation. There are other considerations too (faulty shooter valve not giving you a full intitial start stream), but they're all addressed during a conventional carb rebuild...

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    • David M.
      Very Frequent User
      • September 30, 2004
      • 515

      #3
      Re: C3 fuel problem

      You may still have a bad pump. It just could be weak and not over coming the float and needle valve resistance in the carb, yet still push gas into a can. If you feel confident, purchase a decent fuel/vacuum test gauge(should have one for fine tuning anyway)at a local "known" parts retailer. Test the pumps PSI while cranking the engine a few revolutions. Your looking for 5-7lbs of PSI.

      SAFETY TIPS: Car should be cool. Make sure the gauge is hooked tightly to the fuel line, if in fact it is good, 5-7 will present a fire hazard and a mess. Disable the ignition coil and insulate the pulled lead(negitive/black wire for points, + wire for HEI). If the pumps good, than as mentioned in the last post, its carb rebuild time. Let us know if you need help in that area too, because it needs to be done right.

      INFO: -Gauge brands to look for are: Lyle,KD or Snap-On if you like top shelf.

      -You should purchase the $15-20 Haynes or Chilton repair manuals for your

      car. Great general info for the do-it-yourselfer along with safety tips.
      Regards,Dave

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