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SVT Help

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  • SVT Help

    Hi All,

    I have the stock SVT motor in my car and was out this morning for a trip to break it in.

    After about 50 minutes crusing at 70mph it started to stumble then died. It wouldn't refire and had to be towed home.

    As I cranked it, the spedo jumped around and no luck getting it started.

    Once I got it to the repair shop it fired right up and I drove it home.

    Where do I begin? Would a ground fault kill the car like this ? If so, which ground should I start with?

    You guys probably have more SVT motored cars than anyone. Help. I don't have the codes yet but will later, I hope.

    Joe

    www.thecaterhamproject.com

  • #2
    Hmm.


    I can't offer much help with this little information, so I'll go through the obvious.

    Check you fuses.

    The engine is normally grounded to the tubular through a cable running from the engine to one of the forward engine mounts. There is also a wire going from the engine to the negative ground of the battery. I doubt very much that these are the source of your problems, but check them anyway.

    I assume that you have a stock ECU. The OBDII error codes would help (if any). A stock ECU will continue to run the engine in limp home mode even if one or more sensors are dead, with the exception of the crank sensor that sits under the exhaust manifold against the flywheel. Check this connector.

    Check that the mating connector between the engine and chassis harness is fully pushed in. It's a big fat square connector residing somewhere under your intake manifold. Check all connectors, for that matter.

    Fire up the car and let it idle until it is warm. Try to shake the wiring harness at different points to see if you can induce the fault. It may be a good idea to jack up the car before you do this so that you can get under it and reach all the wires.

    My car had a wiring fault, source unknown, when I got it which I could only bypass by grounding the black cable of the unused speedo connector of the engine harness. As long as this connector was not grounded, I would only get intermettent ignition.

    This three pin connector sits on the harness on top of the bell housing and should be easy to find. You can try this if everything else fails. Please make sure you find the right pin in this connector to ground...

    /Magnus F.

    Comment


    • #3
      SVT Help

      Thanks Magnus,

      I will work my way through all these tonight. Hopefully the shop I took it to left the codes in there. I'll pull them myself tonight if they did.

      Does it sound like I'm on the correct path of looking for a ground fault?

      I've never seen the speedo jump around before today. I guess thats why I'm starting with the grounds.

      Thanks again. I'll report any codes or other stuff I find.

      Joe

      www.thecaterhamproject.com

      Comment


      • #4
        SVT Help

        Joe

        I had a similar problem with my car. (electric speedo never bounced)

        The engine would suddenly quit. Anywhere from a few seconds to an hour later it would start again. This went on for months. Not often but on random occasions. When the engine quit you could not hear the electric fuel pump running when the key was turned on, (it should run for about 1 sec) so I at first thought it was the fuel pump or inertial cutoff switch connections. I'd had my inertial fuel pump switch trip when straight and level on the freeway, similar symptom.

        I too tried to read the codes without any help. Finally it failed in my driveway and I hooked the code reader up. It could not find the PCM (ECU). The computer was not getting any power.

        I checked every power and ground connection to the ECU. While I had it apart I replaced my ignition key with a couple of toggle switches, one for power and a momentary for start. The problem went away.

        Best guess is there was something wrong with the switch itself. I see that you did something similar but did not see if you eliminated the keyed switch.

        It saves about 1.5 lbs and I don't need to worry about where I put the key.

        Please let us know what you find.

        Doug

        Comment


        • #5
          I had a similar experience as Doug just last Sunday on my way home from Willow Springs. My knee bumped the ignitiion key and the engine died, although the key was still in the on position. The switch has alway been "sloppy" since I bought the car. Needless to say, I'm going to replace it.

          I do have a question: Longacre sells both and on/off ignition switch and a seperate push button for the starter, and a three position ignition switch with down as off, middle as on, and up as a momentary on for the starter. Any opinions on which would be the better system, or is it just personal preference? Thanks,

          Stan

          Comment


          • #6
            Stan,

            It depends on which cool factor you're after. Push button is the Olde Englishe Waye (note the needless 'e' at the end of each word, as in Ye Olde Porno Shoppe) while the toggle is more aviation-ish.

            My vote (for your car - what?) goes to the aircraft type - the L7 Club mag is called 'Low Flying' after all...
            Chris
            ------------
            A day you don't go a hundred is a day wasted

            Comment


            • #7
              SVT Help

              Thanks All,

              I ran it last night in the garage. I couldn't get any codes other than those that should be there like the speed sensor which isn't hooked up.

              Poked, proded and shook everything I could find. No fuses blown, Nothing stands out to me.

              I'm going to try running it for an extended period tonight with short trips around the block to see if I can get it to fail.

              Once it fails I want to try to see the codes again and what the fuel pressure is.

              I don't have a key barrel on my car. Just a covered toggle. Since it died on the xway I couldn't hear the fuel pump prime due to traffic noise. At home I can hear it no problem.

              Couldn't find any grounds that where suspect. I'll continue to look at them.

              The speedo jumping is the only thing I can point to that was wierd other than I was sitting there dead on the xway.

              The repair shop said the Fuel Pump Control Modual might do this. Anyone ever have one of these fail?

              Joe

              www.thecaterhamproject.com

              Comment


              • #8
                SVT Help

                Looking at my post I didn't mention that when it died, it died "softly".

                It started running ruff and started cutting out then wouldn't continue to run and finaly just quit. It poped a little when cranking but not much and wouldn't catch. This all happend in the course of about mile at 70mph

                That's the why the jumping speedo seemed so wierd.

                Joe

                Comment


                • #9
                  SVT Help

                  Joe

                  My car has a stock Zetec with stock intake. I've had the connection to the mass air flow sensor come off and cause it to run rough. It didn't quit but then I fixed it right away.

                  Doug

                  Comment


                  • #10
                    From your description of the failure, I would suspect the fuel pump relay. I had some troubles with a relay that were fixed by removing and replacing the relay a number of times (to clean the gunk off of the terminals). Cheap and easy to try.

                    Also did the failure only happen when the motor was hot?

                    Cheers,

                    Tom
                    Tom "ELV15" Jones
                    http://PIErats.com

                    Comment


                    • #11
                      SVT Help

                      I'll try the relay cleaning. It did it after about 40 miles of xway crusing. It was up to temperature but (thankfuly) not running hot.

                      To that extent I haven't run it for more than 10-15 minutes at a time since the failure.

                      Tonight I'll do an extended run in the subdivison and driveway.

                      Joe

                      Comment


                      • #12
                        The fuel pump relay is controlled by the (stock) ECU in order to avoid having the fuel pump operate when the engine is not running (or cranking). This, however is not really an issue since during ignition on with a no engine running, the fuel will simply be returned to the tank.

                        My fuel pump relay was strange as well, and I went through two of them until I finally gave up and hotwired the fuel pump to the ignition. End of problems.

                        /Magnus F.

                        Comment


                        • #13
                          On my car there is also a relay that controls the injectors.

                          Tom
                          Tom "ELV15" Jones
                          http://PIErats.com

                          Comment


                          • #14
                            SVT Help

                            I checked evrything I could friday night and yesterday. Can't find any bad grounds or obvious electrical troubles.

                            It died last night again after runnig well Friday night and Saturday. Inculding an hour trip + 40 minute Blat. Then on the return trip home it died 40 minutes into it. Once again while at xway speeds it started to cough then died.

                            I did find a heater hose contacting the fuel line. I believe both times it quit I had the heat on. MAYBE vapor lock.

                            Vapor lock is a totaly differant direction than a ground fault. But both times it quit it was after extended running and both times the car restarted after sitting for about 1 1/2 - 2 hours. If I can't figure this out today It's going to a real repair shop. I'm starting to go in circles here and I'll never track this down on my own.

                            Thanks for all yor input if I find anything that makes any sense I'll let you know.

                            Joe

                            www.thecaterhamproject.com

                            Comment


                            • #15
                              SVT Help

                              Hi All,

                              Well after lots of frustration and a total of three trips home by tow or trailer I found the trouble. It was my fuel cell!!!

                              The surge tank inside the cell didn't have any holes or valves in the bottom of the wall. As the gas level would go down fuel would go over the top of the tank wall for a while when running on level ground. After that I had to be on a hilly road for the surge tank to refill.

                              I would run out of gas with over 1/2 a tank left in the main tank and on the gauge.

                              That's the last thing I expected or would have looked for. As of last night I now have some nice 1 inch holes and check valves in my surge tank wall. I'm just waiting for my new fuel pump to arrive to put the whole thing back together. The pump may be ok but why chance it since it's out of the car and apart.

                              Thanks for all your help.

                              Joe

                              Comment

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