Oversized fuel pump and affects on performance

[T3rminator]

Got a general question. Can having a higher flow fuel pump affect performance?

I've got a 5.4L 3v, its done 320,000kms. The original fuel pump is 90LPH.

I replaced it with a delphi xr8 fuel pump, which flows at 150LPH.

I've noticed that from idle to about 3500RPM, the car has picked up a lot of go. BUT.....at wide open throttle, it doesn't seem to go as hard as the stock fuel pump.

The car was originally tuned on the stock fuel pump.

Is it in my head or can an oversized fuel pump affect top end performance? Do I need to go get a touch up tune done?

Car still runs the same regulator.

[Interceptor]

There shouldnt be any difference in performance, just more fuel going back though the return line.

It'd be interesting to see what the AFR's are line when it gets dyno'd

[39ClevoUte]

I saw an instance where the fuel in the tank was boiling. We put a cooler in the return line which "fixed" it. We assume that the volume of fuel being forced through the small regulator orrifice was causing friction and heating the fuel? Interested in anyone elses experience.

[cs123]

Originally Posted by 39ClevoUte

I saw an instance where the fuel in the tank was boiling. We put a cooler in the return line which "fixed" it. We assume that the volume of fuel being forced through the small regulator orrifice was causing friction and heating the fuel? Interested in anyone elses experience.

My fairlane had a carb and high flow fuel pump with 12 lines. Great for drag racing but driving it on the street for 30 mins and the fuel got very hot.

I wouldn't mind betting in this case that the new fuel pump might be delivering fuel at a higher pressure compared to the old one and that has thrown the tune out.

I think a run on a dyno would be a good idea