My sidekick has a subtle, high frequency surge under load.  I see that there is a fuel pulsation damper on the back of the fuel rail that is supposed to cancel out any effects of the injector pulses.  I haven't had a vehicle with one of these before.  Note that this is *not* the fuel pressure regulator.

So-- does anyone know anything about these?  Do they fail?  Can a failed fuel pulsation damper cause symptoms like the ones I'm seeing?

Thanks.

I have not heard of that, but you can get that from a loose timing belt, let the spring do it's job then take your finger and give it a little extra, also make sure(16 valve)that you keep the tubes in the head clean with electrical cleaner or your spark plug wires will short out in there, oil is the main cause but your plugs could be loose also.