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MS1 Blowing Fuses

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  • MS1 Blowing Fuses

    I have an MS1 v2.2 that's a little over 9 years old and has given me a little over 30,000 miles of mostly trouble free driving. It recently has started blowing the main 3A fuse. I just changed from a Ford truck MPI manifold to a single four bbl setup. It blew the fuse once before, but since the swap it has done it four times. I've checked for shorts. It's only done it on decel. The only electronic component I've changed is the TPS. It is a modified Panasonic pot that is now 5k ohm. Could this be causing the issue?

    Thanks,
    Kevin

  • #2
    A 5000 ohm TPS won't draw anywhere near 3 amps unless it's wired very wrong.

    What's the resistance on the TBI injectors? Are you using PWM current limiting with them?

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    • #3
      I'm running the same high impedance 42lb ones from the previous intake. This is a multiport set up. I've checked and rechecked everything going to the TPS. I no longer think it's the problem. I think I have a short somewhere else. I've done a bunch of wire wiggling and repositioning. I haven't found anything but it hasn't blown the fuse again. When it does it, it completely floods the engine. I actually had fire coming out of an exhaust leak when I tried to restart the first time. I've fixed the leak.

      Thanks,
      Kevin

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      • #4
        Originally posted by ka67_72 View Post
        I'm running the same high impedance 42lb ones from the previous intake. This is a multiport set up. I've checked and rechecked everything going to the TPS. I no longer think it's the problem. I think I have a short somewhere else. I've done a bunch of wire wiggling and repositioning. I haven't found anything but it hasn't blown the fuse again. When it does it, it completely floods the engine. I actually had fire coming out of an exhaust leak when I tried to restart the first time. I've fixed the leak.

        Thanks,
        Kevin
        It floods the engine because the ECU is powered off, and it's grounds are active (including to the injectors) and your injectors, if they still have power, are being held wide open. *this is bad news for your injectors* - you might want to power them off a relay that is downstream of the blowing fuse. So the injector power goes out any time your ECU loses its power.

        Meanwhile - I have seen fuel pumps cause voltage spikes that do exactly what you describe.
        www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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        • #5
          I think I will add that relay. I key it off as soon as I notice, but not having to flood clear it would be nice. I'm not running the pumps off the MS. I've put 180 miles on it since Monday and it hasn't blown again. The new intake is a Victor Jr knock off. I've really been surprised at how much better it seems vs the tall truck MPI manifold. I've had to add a lot of fuel to the VE table. I was running 15 psi in the old manifold. I haven't got past 5 in the new setup yet but it feels way stronger than before at that level.

          Thanks,
          Kevin

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