How low are we talking?

 

well with id1000 injectors my idle pressure is around 35psi as more is not needed for my power level and the pump has been reliable I would imagine the relay setup helps as an electric motor uses more amps and runs hotter the lower the voltage

 

I ran a mechanical gauge on the dyno haven't checked it in a while did a fast group drive with nsx car did very well and that was pushing in 100f heat for 125miles. I run it down to a 1/4 tank regularly though I wont drive hard at that fuel level.

 

I recently had this exact issue on the dyno with an Aeromotive 340. I was watching my fuel pressure just drop off a ledge as the tuner was getting up in the rev range, then he stopped the pull as my mix went lean at the same time. We deduced that the pump was on its way out. The pump was really hot when we took it out. I don't know if I was to blame for killing the pump because I did run it down to a quarter tank or less when driving it on the street, but that was just dailyish driving. Anytime I was autocrossing it had a full tank. Probably still killed it myself by running it low though.

 

And walbro isn't so bad with low levels of fuel?

 

I think all aftermarket pumps are pretty bad with low fuel levels.

The Walbro gets REALLY noisy when its low on fuel.

 

That sucks. Tank is small as it is.

So under 1/4 tank. Fill it up? Or half tank?

 

if your driving on the highway in the heat I wouldn't go much below a 1/2 tank or if you're driving it hard. in the cooler weather you can get away with 1/4 tank but you shouldn't go much below that and I recommend an adjustable fpr so you aren't working the system harder than needed. that's the reason you have big injectors and large fuel pump we turned the fuel down to 20psi and the car still ran good I just bumped it up to near stock just because. remember a pump has more volume at lower pressure so once you get up to 65psi volume starts to fall like a rock. does that make sense? I think this is why my walbro got noisy low voltage high pressure low volume. I was maxing out the duration on the old 650cc injectors and it was all due to inadequate fuel volume lowering the pressure increased the volume and got my injector duration. down now with the 1000cc injectors I am at 45% duty cycle at 360whp so lots of head room

 

I have a MY 06, no return line. No FPR. Run a Aero 340 with stock wiring. Routinely run the tank to near zero. Ran out of gas on the track once. I have none of your problems. Pump is quite.

 

the returnless system has much more head room than the return systems of the ap1 04-05 ap2 that includes your regulator so your fuel pressure will be the same as the factory pump we have more trouble with our system because of the smaller regulator causing the base pressure to be 10psi too high causing volume loss on the top end and higher amp draw.