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Carb trouble...blown power valve?

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    #1

    Carb trouble...blown power valve?

    This morning on my way to school I had a rough start. That stupid glass filter unscrewed and dumped fuel all over the motor at about 300ft from my house in the pouring rain. The car died and I pulled off. So I got out and fixed that dumbass filter and mopped up the fuel with some rags I had in the trunk and left the rags in the ditch. When I fired the car back up it back fired once and i went back home to wash up so I didnt smell like gasoline and change my soaked shirt(but I still smelled like gas tho :cuss: ).

    On my way to school I noticed the car now stumbles pretty bad when you stab it. Also when its still not fully warm it will stutter through the rpm range. So I messed with the Acc pump and gave it less of a pump shot. It helped a lil but its still there. Once the car is above 3500rpm there are no problems, runs great. Thats what led me to think the accelerator pump is out of whack but I cant adjust it anymore. So now I think the power valve has blown when it backfired. I've never had a power valve go bad so I'm not sure.

    The car was running fine before this all happened so I'm not sure why its outta whack.

    2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
    My rod is glowing, my bead is clean, my middle name is acetylene
    Tags: None
    #2
    You have a holley...that's the issue It's prolly the PV. They don't like backfires.
    Builder/Owner of Badass Panther Wagons

    Busy maintaining a fleet of Fords

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      #3
      Ive backfired through my Holley several times with no problem. Thankfully it came with a PV protection circuit.
      http://secondhandracing.com/Home.aspx
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      R.I.P. Jason P Harrill 6-12-06

      http://www.grandmarq.net/vb/showthread.php?t=5634

      Comment

        #4
        I've had it backfire alot way back when my floats were sticking, I dont think the PV went bad then. I since rebuilt the carb and replaced the PV. Is there anyway to tell if the PV is bad? If it is I'll replace it and get that kit from spectre or whatever and add my own blowout protection.

        2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
        My rod is glowing, my bead is clean, my middle name is acetylene

        Comment

          #5
          You can turn the idle mixture screws all the way in and it still runs the power valve is bad.
          Scars are tatoos of the fearless

          Comment

            #6
            Ok I'll try it tomorrow when I got time. Thanks mangs!

            2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
            My rod is glowing, my bead is clean, my middle name is acetylene

            Comment

              #7
              The newer ones have a power valve protection setup, which can be easily retrofitted into an older carb that didn't have it.

              http://www.holley.com/125-500.asp

              Thats the part you need if its an older carb.
              86 Lincoln Town Car (Galactica).
              5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

              91 Lincoln Mark VII LSC grandpa spec white and cranberry

              1984 Lincoln Continental TurboDiesel - rolls coal

              Originally posted by phayzer5
              I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

              Comment

                #8
                Don't use aftermarket stuff.

                Use genuine holley parts.
                1983 Grand Marquis 2Dr Sedan "Mercules"
                Tremec TKO conversion, hydraulic clutch, HURST equipped!

                Comment

                  #9
                  alright, thanks for the heads up.

                  Shitty night, we had our football game tonight instead of friday cause of the jewish holiday, and I have to go school tomarrow. We crushed the team 50-7 but my car barely made it home. I told you guys how it would hesitate reving through the rpm range before its warmed up, well now it will barely run. The car is bellowing smoke, wont idle at all. I also cant let off the gas or it will die while driving so I had to drive while feathering the brakes to keep the rpms up. It just stutters completely through the rpm range trying to rev it. One thing tho, the car is really really fast now at full throttle when the rpms get up. Maybe I might step up jet sizes once i get this figured out.

                  I'm not sure if a power valve would cause the car not to run at all, even if it is blown. I think I might grab the renew kit while I'm at it cause this aint right. Maybe the floats are sticking....I dunno. I'm mighty tired, and dont really want to think about this now. Shit, I dont think I'm ever going to have a day where I can thoroughly enjoy it. damnit!

                  2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
                  My rod is glowing, my bead is clean, my middle name is acetylene

                  Comment

                    #10
                    Question....If I grab a new power valve, what primary stage opening vaccum should I get? Should I get a dual stage or single stage? High flow or standard?The car now pulls around 14-16" of vaccum at idle.

                    2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
                    My rod is glowing, my bead is clean, my middle name is acetylene

                    Comment

                      #11
                      Whats your vacuum at cruse speed
                      Scars are tatoos of the fearless

                      Comment

                        #12
                        not too sure, never hooked the gauge to it and drove it. Is there a general rule of thumb to figure out what PV you need?

                        2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
                        My rod is glowing, my bead is clean, my middle name is acetylene

                        Comment

                          #13
                          Yep need to know your idle and normal cruse vacuum. If you like to cruse at 80 70 need to know the vacuum. You shouldnt need a dual stage thats usally for truck hauling loads.
                          Scars are tatoos of the fearless

                          Comment

                            #14
                            I was looking on holley's website and they gave two different ways to figure out what power valve you need. The one told you to put the car in gear and check your vaccum and then divide that number by two.

                            The other one said to take your idle vaccum and go 2" under that, but that doesnt seem right to me.

                            I'm gonna go out now and rule out some other things such as crap in the needle and seat and make sure the floats are ok.

                            2009 Ford F-350 6.4 powerstroke diesel. 1977 Ford F-150 built 300 six, 5 speed trans. 1976 MG MGB roadster, 359w, t5 5 speed. 1996 Kawasaki ninja ZX6R.
                            My rod is glowing, my bead is clean, my middle name is acetylene

                            Comment

                              #15
                              Originally posted by Mercmarquis
                              I was looking on holley's website and they gave two different ways to figure out what power valve you need. The one told you to put the car in gear and check your vaccum and then divide that number by two.

                              The other one said to take your idle vaccum and go 2" under that, but that doesnt seem right to me.

                              I'm gonna go out now and rule out some other things such as crap in the needle and seat and make sure the floats are ok.
                              It can be correct depends on your cam your vacuum say is 14 at idle at cruse it could drop to 10 which would open a power valve that was a 12. it woulld kill some fuel economy. A real hot cam might idle at 5 or 6" and cruse at 10. This situation can cause some real problems.
                              Scars are tatoos of the fearless

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