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fuel system problems

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  • fuel system problems

    I have some sort of fuel system gremlin . I have a Caterham with a Duratec2.0. In 2005 I replaced the in tank pump (which failed) with an external MSD 2225. I used Magnus' excellent pictorial instructions. The system worked fine for a couple of years, then I had a nearly complete loss of fuel pressure. I got it towed home, and looked it over, jiggled a few wires twisted a few fittings, and it healed itself. Bad deal. I then had no idea what was wrong. I was reluctant to drive it any distance from home. Earlier this month, driving on the same road where I had my previous problem, the same situation occurred. I put in another MSD 2225, thinking that was the problem. Apparently not. So far I have eliminated the fuel tank/pickup as the problem, and I'm fairly sure it isn't the fuel pressure regulator. I'm still trying to get to the bottom of the problem. It has been suggested that I might need a relay in the system, since the new pump might need one. I don't seem to recall Magnus using one, and he is apparently having no problems with his install. I'm basically lost. Any suggestions?

  • #2
    There should already be a relay for the fuel pump in with the fuses and other relays.

    On mine it's the bottom relay. See poor quality but offical wiring diagram attached. See also the wiring diagrams in the assembly guide as some of those circuits are the same. You can download the assembly guide from this site someplace.

    Check the fuses themselves. The fusable link that connected the two spades was a mechanical press fit. You could wiggle the spades and see the connection move. I don't really know if that ever caused a problem but I replaced all my fuses with ones where the spades and fusable link are one piece.

    Check the wires you wiggled to get it to work before, be sure all the crimp on connectors are solid and not frayed so only one or two strands are connected.

    Check all the ground wires to the fuel pump and from the engine or battery to chassis.

    Check the connections to the inertial cutoff switch. Typically these are mounted on the firewall on the right had side. Also check the switch itself. OK to bypass it for testing too.

    If this is not practical run a separate wire from the ignition switch thru a relay to the pump. At least to test it. This should also go thru an inertial cutoff switch if you plan on leaving it that way.

    I had what seemed to be a fuel pump problem but it turned out to be the power wire to the ECU. This is a green wire coming out of the chassis wiring harness. The push on blade connector wasn't crimped correctly so power was intermittent. It would work for months, fail for 30 seconds to two hours and then before I could find it start to work again.

    This was on the engine wiring side of the harness, the crimp being done by Caterham USA or whoever made the stock Zetec harness. I don't believe I have had any problems with the Caterham UK factory wiring harness or it's connectors.

    Magnus' fuel pump is not controlled by the ECU and it runs all the time.

    My ECU shuts it off after a few seconds unless the engine is turning.

    Attached Files
    Last edited by Doug Liedblad; June 27, 2008, 05:45 PM.