MCX Apex Turbo Guys - Question about the injectors

[tom]

So help me out here. When I turn the key (not start it) the fuel pumps run & pressurize, is that correct? I have the secondary fuel pump installed as well. What do the injectors inside the plenum do (before starting), anything?

Reason I ask, is the 4 MCX injectors are making a god aweful, weak noise when I turn the key on. Usually it's just a very noticable electic motor noise, which I always assumed was the secondary fuel pump running. Now the injectors are making this terrible sounding, faint, noise. Best way I can describe it. I put my hand on the secondary fuel pump and I can definitely feel vibration in it, likes it doing 'something'.

Sled ran like a champ all day prior to this and also started and ran fine loading it onto a trailer after this started. ANy ideas?

Also do the MCX injectors only kick in fuel 3/4 up to WOT?

 

[rxrider]

Fuel pumps will pressurize, correct.

Injectors will not do anything until 3 lbs, when they start spraying more fuel.

It's the MCX fuelpump making noise, all them kits does it, even my carbed RX-1 does. The pump starts running full power as soon as you turn on ignition, the injection fuel rail gets pressurized and since there is no fuel usage with the enging not running all fuel is returned to the gas tank. You should hear the fuel flowing into the gas tank.

The injectors will feed fuel accordingly whenever boost pressure exceeds 3 lbs. At all throttle positions.

The noise you hear is it louder at first and then reduces in volume after a second or two? This is what it sounds like starting my friends MCX400 Apex.

 

[tom]

So why would my MCX injectors be making noise now? The sound is quieter than the usual noise it makes, but sounds absolutely terrible. I'll see if I can't get an audio clip of it.

 

[rxrider]

Yeah that would be great.