Announcement

Collapse
No announcement yet.

Avanti bogs down under full throttle - update

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

  • #46
    I may have more than one problem.[|)] My brother said that when he drove it to the body shop on Friday, it ran OK as long as he didn't punch it. But he noticed, quite by accident, that there didn't seem to be much fuel visible in the filter. He checked it several more times and the filter was almost devoid of any gas, whereas we expect it to remain virtually full on most cars. The situation has gotten a little more difficult since my first posting. The car seems to run better if you manually shift it, but it still won't take full throttle at a standing start. Now it doesn't want to take pedal to the floor anytime. It bogs at 40 mph and starts choking back if you gap it at 70 mph. I don't think it could be forced to 100 mph. My brother thinks it is somehow being fuel starved at high RPM. [xx(] The only fuel system component that hasn't been refurbed, replaced or rebuilt is the mechanical fuel pump. All the debris and crap that was is the tank may have ruined it.[}] Any ideas are welcome. We'll check it out. Thanks. [^]


    quote:Originally posted by bige

    Correct me if I'm wrong. Your problem occurs when you are cruising along at 40 mph or so and you put your foot to the floor and at that moment the car bogs but then takes off as it's supposed too? If that's the case you do not have fuel pressure issue. Look at the logic of it. While cruising fuel demand is low the bowls are full. When you put your foot down the car has not reached a level where demand is outpacing fuel delivery. Also if I read correctly it doesn't bog when you downshift manually so how come fuel pressure is OK then? Your car and money but poor fuel pressure does not cause the problem you are experiencing if I understood it correctly



    1988 "Beater" Avanti---R5388 @ Macungie 2006
    edp/NC
    '63 Avanti
    '66 Commander
    edp/NC
    \'63 Avanti
    \'66 Commander

    Comment


    • #47
      quote:Originally posted by bige

      Correct me if I'm wrong. Your problem occurs when you are cruising along at 40 mph or so and you put your foot to the floor and at that moment the car bogs but then takes off as it's supposed too? If that's the case you do not have fuel pressure issue. Look at the logic of it. While cruising fuel demand is low the bowls are full. When you put your foot down the car has not reached a level where demand is outpacing fuel delivery. Also if I read correctly it doesn't bog when you downshift manually so how come fuel pressure is OK then? Your car and money but poor fuel pressure does not cause the problem you are experiencing if I understood it correctly



      1988 "Beater" Avanti---R5388 @ Macungie 2006
      I don't think it's fuel pressure related as much as volume. Under boost, the factory pump it hard pressed to keep up, even in good condition. A rebuilt, or new mechanical pump might do the trick, but I've had more than a few that need a electric in the back too.

      JDP/Maryland
      JDP Maryland

      Comment


      • #48
        By all means, rebuild the fuel pump! An older diaparaham will have less volume carrying ability. I rebuilt mine on my R-2 GT and there was a noticeable difference. Debris under a check valve seat can also lead to a loss of performance as you describe. Kits are availiable from D Tbow or Jon Myers. Russ Farris

        1963 GT Hawk R-2 4-speed
        1964 Avanti R-1 Auto
        1963 GT Hawk R-2 4-speed
        1964 Avanti R-1 Auto

        Comment


        • #49
          I've got a new Carter R2 fuel pump that originally came from Myers. I suspect we'll install it now and maybe get an electric booster pump like JDP suggested too. Apparently, it won't hurt to snake the timing up a bit either. [^]


          quote:Originally posted by maxpower1954

          By all means, rebuild the fuel pump! An older diaparaham will have less volume carrying ability. I rebuilt mine on my R-2 GT and there was a noticeable difference. Debris under a check valve seat can also lead to a loss of performance as you describe. Kits are availiable from D Tbow or Jon Myers. Russ Farris

          1963 GT Hawk R-2 4-speed
          1964 Avanti R-1 Auto
          edp/NC
          '63 Avanti
          '66 Commander
          edp/NC
          \'63 Avanti
          \'66 Commander

          Comment


          • #50
            Our 82 Avanti with the 305 CI was doing the same thing, idled OK and drove fine unless you put your foot down, then the car bogged down and lost power. We had the carb (Rochester 4 bbl) rebuilt and it was the float level that was causing the problem. Runs like a scalded dog(small dog) now.

            Steve

            Comment


            • #51
              Thank you for reminding me.[^] The setting of the float level was carefully considered when the carb was rebuilt. If not set correctly it can wreak havoc on performance. We'll have to revisit it anyway when we put in the new plunger and ball valve. And, it sounds like the new R2 fuel pump is going to be installed in any case.

              ps We noted that the Quadrajet carb on my brother's Ram Air T/A gushes fuel when the throttle is pulled back all the way with the car turned off. The AFB 4-V on the Avanti just produces a very weak squirt.

              quote:Originally posted by Avanti82

              Our 82 Avanti with the 305 CI was doing the same thing, idled OK and drove fine unless you put your foot down, then the car bogged down and lost power. We had the carb (Rochester 4 bbl) rebuilt and it was the float level that was causing the problem. Runs like a scalded dog(small dog) now.

              Steve
              edp/NC
              '63 Avanti
              '66 Commander
              edp/NC
              \'63 Avanti
              \'66 Commander

              Comment

              Working...
              X