Cutting out at speed?

Discussion in 'Ranchero Tech Help' started by 2beast, Jul 23, 2011.

  1. 2beast

    2beast In Third Gear

    Messages:
    223
    Location:
    Streator, Il
    I have a 72 351CJ Ranchero.

    It runs fine and then while driving at highway speed (or sometimes just local driving) it will start to cut out and miss.
    Can happen when the engine is either hot or cold.
    Does not happen all of the time.

    I can keep it going by pumping the throttle.
    It acts like it is not getting fuel or ignition maybe cutting out..

    It will surge as if running fine for a few seconds then sputter a few seconds.
    on off, on off, on off.............frequently chirping the tires each time.

    It may last a minute or five and then clear up and continue running fine for the next 30-40 miles :confused:

    I have new fuel pump, fuel filter, coil, condensor..............

    Maybe something is floating around in the tank blocking the pickup?
    Any ideas would be helpful.

    Thanks,

    Greg
     
    Last edited by a moderator: Jul 23, 2011
  2. Dan the ranchero man

    Dan the ranchero man MODERATOR Staff Member

    Messages:
    4,183
    Location:
    Mchenry , IL
    If you are pumping the throttle and that is what will keep it going sounds like a fuel delivery issue. I would get a fuel pressure gauge on this thing and see what it is doing when the sputtering starts. Your fuel pressure should be bettween 4-7 PSI. Yes you could have some stuff in the tank blocking the inlet OR you could be sucking in air through a damaged line or pick up tube in the tank. Does it do this with a full tank? half tank? or close to empty? Check for kinks in the lines and new fuel pump and filter does not always mean properly working. I would try one more thing before ripping things apart. You may have water in the lines that you picked up from filling the tank. Get some heat and put that in the tank and refill (in that order) then drive it around for a few miles and see what happens. I get more water in the summer because of the high humidity and the cold fuel coming from the underground storage that I do in the winter.
     
  3. 2beast

    2beast In Third Gear

    Messages:
    223
    Location:
    Streator, Il
    Tonight it had a full tank.
    Not really sure about previous incidents.

    Thanks for the ideas, it will give me some places to start looking.

    Greg
     
  4. 2beast

    2beast In Third Gear

    Messages:
    223
    Location:
    Streator, Il
    I checked the fuel lines and they looked OK.
    Changed out some of the rubber lines as well.

    It seemed to be running ok.

    Last night I took it out of town for a cruise night.
    It lost power again within a mile of home but it cleared and I went on (foolishly).

    About 20 miles later it lost power again and I had trouble starting it.
    Once it started I headed for home.

    It run beautifully all the way home.

    I need to get a fuel pressure gauge and see what is going on.
    Probably one of those small inline gauges I guess.

    This time with about 3/4 tank of fuel.

    I will find it but it is frustrating as heck right now :mad:

    Greg
     
    Last edited by a moderator: Jul 31, 2011
  5. steeread

    steeread Guest

    If you can occasionally "chirp" the tires, then problem is upstream from the carb. How old is the gas tank and sender/pickup unit? If the pickup filter is clogged with rust/varnish etcetera, it could produce the symptoms you describe.

    RooDee has seemed to "run out of gas" on occasion, while I still had gas, but I have not had the time to drop the tank and slosh it out.
     
    Last edited by a moderator: Jul 31, 2011
  6. Louis

    Louis In Overdrive

    Messages:
    555
    Location:
    Milford, CT
    Change the fuel filter, first.
     
  7. 2beast

    2beast In Third Gear

    Messages:
    223
    Location:
    Streator, Il
    Fuel filter has been changed.

    The tank is sounding more like my possible source of problems.

    Greg
     
  8. Rancherous

    Rancherous Administrator Staff Member

    Messages:
    8,709
    Location:
    Buffalo, NY
  9. 2beast

    2beast In Third Gear

    Messages:
    223
    Location:
    Streator, Il
    Thank you.

    I will give that a try.

    Greg
     
  10. 2beast

    2beast In Third Gear

    Messages:
    223
    Location:
    Streator, Il
    I blew air back through the lines tonight.
    I then drove about 50 miles with absolutely no problems:cool::cool:

    I will take it out again in the next couple days to try it again but so far so good! :)

    Thanks,

    Greg
     

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