To answer that question in the past, I built a "spark detector" (neon bulb with a sensor wire) that flickers all the time spark is present. I also built a simple "tell-tale" lamp, connected in to the fuel pump wire under the rear seat.

Both work well.

If the fuel relay or ecu cut out, the "tell-tale" goes out (because the fuel pump loses the 12 volts).

If spark dies, the neon bulb stops flickering. However, keep in mind that when the FI ecu loses the spark primary signal, it ALSO kills the fuel pump (to prevent flooding and/or a nasty fire). So you must be careful in your observations -- you might see the fuel pump "telltale" go out and think that the relay has failed when, in fact, it's doing just the right thing.

Be absoltely sure the 25-amp fuse and holder are perfect.

Clean and tighten ALL the fuses in the fuse box.

And consider what the other poster said about a mis-adjusted or flaky throttle switch, although that will only influence idle when the throttle is at idle position.


Don Foster (near Cape Cod, MA)