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74 TR6 loses power, and sputters puzzled

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  • 74 TR6 loses power, and sputters puzzled

    I pulled my plugs, and cleaned them, also I lightly sanded the rotor button, and contacts in the Distributor cap. Afterward I took it for a spin, the Idle was up a bit to 1500, not unusual in the summertime. On the way home the engine was sputtering, and no matter how much i pumped the gas, the car would not speed up. I limped home, replaced the plugs, checked the dist cap, no cracks. My local mech says it's got to be elec. I have a Petronix ignition, no points. The car ran fine before I pulled the plugs, I did not mix up the wires, and they are on securely. Any ideas, where to look?

  • #2
    Does the coil feel hot?
    Also, personally, I never had a lot of success, "cleaning" old, used plugs. It's easy and fairly cheap to just replace them.
    What plugs are you running?
    CF1634U+O Pimento/Chestnut
    2nd owner, since 1975
    Now in Fair Oaks, CA

    Comment


    • TR Robbins
      TR Robbins commented
      Editing a comment
      NKGs, My plugs get carboned up fairly quick. One of my carbs is running rich. Put new plugs in, no luck.

  • #3
    What's the deal with the idle at 1500 because it's the Summer...
    FWIW, I have a hard time relating 'sputtering' to an electrical problem....sounds more like a fuel delivery or even a carb problem.
    Last edited by poolboy; 06-25-2021, 08:15 PM.
    Driving a 1973 TR6
    Doing ZS carb repairs
    email kencorsaw"at"aol.com

    Comment


    • TR Robbins
      TR Robbins commented
      Editing a comment
      When the humidity rises my car idles a bit faster. The reason I think it's electrical is because that's what I was doing just before it started running rough. Prior to that it was running great. Maybe sputtering is a bad description. It's missing, and will not accelerate.

  • #4
    I did sometime ago have a issue where the car lost power - hard to keep running. At the time I had a Pertronix unit and a Lucas "Gold" coil. I replaced to coil wiith one recommended by someone on the forum, I believe it is a Pertronix Branded coil of a particular voltage and Ohms. I have a non-ballasted ignition (1972), yours probably has a resistor. Once the coil was replaced the car ran without any issues. If its not the coil I would tend to go with Poolboys evaluation of your "sputtering" pointing to a carb issue.
    Hard to describe "sputtering"!
    Last edited by ibjean325; 06-25-2021, 09:44 PM.

    Comment


    • TR Robbins
      TR Robbins commented
      Editing a comment
      Yes, I have a flamethrower coil on the car. Maybe a dead miss is a better description. How can I determine if it's electrical, or fuel related? It would seem to be unusual to go from running great, to missing, and loss of power, after cleaning plugs if it was fuel related.

  • #5
    If you still have your old points and condenser, refit them and see if the issue goes away.
    I tried a pertronics set for short while in my '73 but had a steady miss that developed when everything got to normal operating temps. I put the points back in and all was well again.
    I know many run "no points" ignition systems and I have a Pertronics in my 85 XJ6, but for some reason, the Pertronics in particular, doesn't play well with the TR.
    CF1634U+O Pimento/Chestnut
    2nd owner, since 1975
    Now in Fair Oaks, CA

    Comment


    • #6
      Do you have a fuel filter?
      Ralph
      TR250 "Eileen"
      MGB "Merck"
      VW GTI

      Comment


      • #7
        If you have ZS carbs and if you haven't as of yet, I think you should take a close look at the air valve diaphragms for a tear or split.
        Click image for larger version

Name:	Jakes Air Valves 002.JPG
Views:	248
Size:	698.0 KB
ID:	542493
        Driving a 1973 TR6
        Doing ZS carb repairs
        email kencorsaw"at"aol.com

        Comment


        • #8
          I had NGKs for a while but the car didn’t run right so I changed to Champion 12Ys and it ran much better. I also had Pertronix but they burnt one time I inadvertently left the key on for 5 minutes. Put points in and haven’t looked back in 10 years, haven’t even had to adjust them.

          If it’s an intermittent miss as in no fire at a plug, it probably electrical. If it’s a more prolonged loss of power I would think it’s fuel related or a torn diaphragm as Ken suggested. The diaphragm issue is more noticeable on acceleration.
          72 Pimento w/overdrive - Lilred
          67 4A Royal Blue - Lilblue

          Comment


          • #9
            Coil or Pertronix

            I am with baws, Post #2 and #5.

            If a backfire, I might suspect a gas issue. I dont expect plugs, even bad ones not respond to speeding up when pressing the gas pedal.

            Coil or pertronix, post #2 or #5
            '74 TR6 CF13007U aka "Mr. T"
            Custom Blue (Delft-Like) and New Tan (Formerly Mallard and New Tan)
            Points, Ballast Bypassed, Bosch Blue Coil, Moss Cobalt Wires, Champion RN12YC plugs.
            Peaks and tweaks, but the spirit of Original
            Redlines always.
            My wife is the Driver, I'm just the Mechanic....

            Comment


            • #10
              Some of the Pertronix systems need 9 volts or thereabouts to function properly. If you have a ballasted ignition then absent any other changes, you aren't getting 9v to the Pertronix. They have a "workaround" on the website for your model Pertronix (if applicable). I got away with a Pert and a ballasted ignition, and many do, but it can be a problem. Of course the best solution is put in a 3 ohm coil (40,000v) and bypass the resistor wire, then the Pertronix will work as advertised.

              Just a thought if you've tried everything else - you could also just put the points back in as others have suggested.
              1976 TR-6 BRG - CF57239U
              Carbs by Poolboy
              Rear Camber Kit, Rear Hubs by Goodparts
              Gear Reduction Starter by TSI
              Distributor by British Vacuum

              Comment


              • #11
                Positive lead at the coil, one of your plug leads went bad, rotor button. All these things I’ve experienced personally or friends have shared. The rotor button wasn’t visibly bad, but swapping it fixed the issue. I’ve had the positive lead connection at the coil break. Couldn’t see the fact that it was loose and the crimp was just barely holding the wire. Also check the negative wire in the dizzy.
                So much rust, so little time

                64 TR4 Overdrive Surrey
                68 TR250 Soon to have Overdrive & Surrey
                69 TR6 Overdrive Early with fender beads
                71 TR6 Hardtop Soon to have OD
                81 TR8 Injected Automatic...the LAST Automatic

                Comment


                • #12
                  Update- Took it to my Mech. we replaced the plug wires, Dist Cap, adjusted valves, set timing, new plugs. He tried to adjust the carbs, but none of the adjustments made any diff. in other words, he could turn the mixture, or needle valves etc... and (nothing happened). I decided to take it home, and it was the same issue accelerate, and hit a wall (bogs down), then it died and wouldn't run at all. Fuel Pump? or carbs? I have not replaced the Petronix ignition yet. Everything elec. seems to check out. Where do I go from here?

                  Comment


                  • #13
                    Originally posted by poolboy View Post
                    If you have ZS carbs and if you haven't as of yet, I think you should take a close look at the air valve diaphragms for a tear or split.
                    Click image for larger version

Name:	Jakes Air Valves 002.JPG
Views:	248
Size:	698.0 KB
ID:	542493
                    Anybody check these yet ?
                    Driving a 1973 TR6
                    Doing ZS carb repairs
                    email kencorsaw"at"aol.com

                    Comment


                    • #14
                      I think it’s fuel related. If you are getting good pressure and flow at the fuel line on the front carb, I would PM Ken (Poolboy) and make arrangements for him to go through your carbs.

                      When you said he set the timing, have you checked it with a vacuum gauge to see what you have at idle?
                      72 Pimento w/overdrive - Lilred
                      67 4A Royal Blue - Lilblue

                      Comment


                      • TR Robbins
                        TR Robbins commented
                        Editing a comment
                        He set the time, but didn't put a vacuum gauge on it. Whats the best way to rule out the fuel pump? Obviously the cheaper repair.

                    • #15
                      Any way to test the fuel pressure?
                      And yes, vacuum readings would be helpful.
                      I seem to recall a similar issue once, and it turned out to be a weak fuel pump (torn daiphram).
                      Last edited by baws; 07-07-2021, 08:59 PM.
                      CF1634U+O Pimento/Chestnut
                      2nd owner, since 1975
                      Now in Fair Oaks, CA

                      Comment


                      • TR Robbins
                        TR Robbins commented
                        Editing a comment
                        What should the Fuel pump read in pressure? maybe just as well replace it and see what happens. It seems obvious that no fuel is getting to the carbs, as adjustments did not make any difference.

                    74 TR6 loses power, and sputters puzzled

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