Trexthe3rd

Here is what I'm trying to get a grasp on. I have a RX6 single with 850 primary and 1600 secondaries running under 45 psi of fuel pressure. I seem to have run into a fuel limit at only 15 psi boost. My wide band is showing 12.2-12.7 afr at 15 psi and injector duty are both at 90% +.

Here's my question, what setup are you guys running and what injector duty are you seeing at ?? boost level? It seems to me that with 850/1600 at 45 psi, I should have plenty of room at 15 psi on a RX6 (it's a fairly small single as compared to T78 and a few others). Am I wrong??

LUPE

What fuel pump? You've got plenty of injector and pressure.

Wargasm

What's your fuel pressure at 15 PSI boost? It could easily be that your fuel pump isn't keeping up at high load and your pressure is a lot lower than it should be (leading to high duty cycles and high AFR).

P.S. when was the last time you changed your fuel filter?

Trexthe3rd

I'm using the Supra Denso pump, I can't really tell what the fuel pressure is under boost since I can't stick my head under the hood while driving. As for the fuel filter, it's been 20k since I last changed it.

ghostrx7

I would get on a dyno and watch fuel pressure as its driven. or check voltage to the pump, it could be a bunch of things but you should be nowhere near 90% duty cycle. Id watch those air fuel ratios too that is a bit lean. You could also invest in an electronic fuel pressure gauge, if you cant get access to a dyno.

dubulup

upgrade wiring to the pump.

drop base fuel pressure to 38.

Trexthe3rd

My absolute fuel pump pressure is 95 psi so it should be o.k.

Does anyone have an idea what the fuel pressure difference is between having the resistor and bypassing it? The reason I'm asking is, I was monitoring the fuel pressure while playing around with enabling and disabling the fuel pump resistor and I only saw a 1 psi change in the fuel pressure. Searched through the FSM but no luck.

Also, what would be a safe upper limit for fuel pressure? It appears I have hit a limit on the injector output when tuning the RX6 single to 15psi. The injectors are 850/1600. I will be contracting some dyno time to get the fuel pressure under boost, it just seems strange that I would hit this limit so early.
The secondary fuel rail and injectors came from the RX7-store, the primary fuel rail is stock (so is the line from the primary to the secondary), could this be the restriction that is limiting my fuel output?
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myR1

iTrader: (1)

My fuel is set up the same as yours minus the primary injectors. I still have the stock primaries. I am running a TO4R and at 15 psi my duty cyle is only about 75%, so it isn't the primary rail and lines shouldn't be your problem

dubulup

[QUOTE=Trexthe3rd]My absolute fuel pump pressure is 95 psi so it should be o.k.

Does anyone have an idea what the fuel pressure difference is between having the resistor and bypassing it? The reason I'm asking is, I was monitoring the fuel pressure while playing around with enabling and disabling the fuel pump resistor and I only saw a 1 psi change in the fuel pressure. Searched through the FSM but no luck.

QUOTE]

The fuel pump resistor doesn't bump the fuel pressure up, it increases the voltage to the pump (ability to support more pressure). The boost line to the FPR raises the pressure. So, switching from 9V to 12V there should be no increase...minimal if any.