Fuel pump 255 whalbro

At idle i can adjust from around 30 to 45 and 45 to 60 on boost

Small pulley 6lbs

And ap1 RRFPR

 

I would like to take a sec. just to says ...

THANKS !! For those who are helping me.

 

Haha, me too! Gah, this is frustrating even for me to just read. I mean could it be something causing the voltage to drop off to the fuel pump at certain RPM's? Like something pulling voltage away from the pump wiring? Can you check the voltage at the fuel pump? Maybe rev the engine while checking the voltage to make sure its constant and not dropping off?

Just FYI, I have the same setup as you pretty much but I didn't do the relay/beefy wiring to the fuel pump. I'm just using the standard wiring to my Walbro 255. It always is a bit whiny, but hasn't given me the problems you are seeing.

 

Good idea , i will check that voltage.

I might just go ahead and change the pump since its not that expensive and it is the only fuel part that as not been change.

You ever heard of the aem f/ic. Its a piggy back like the e-manage. My local tuner tells me it is perfect for the setup im running. A could throw that new rrfpr back in its box and just put slitly bigger injectors.

 

Btw way. Have you check your fuel presure?

What is it set to at idle ,CT tells me 30-34 and under boost 46-50 psi. And does your pressure ramp up gradualy or does it step up in one shot. Mine it steping up when full throtle is aplied

 

I don't know, as I don't have a fuel pressure gauge setup like yours. But it *should* rise gradually as the boost rises. Where is your vacuum line coming from that you have connected to the top of the RRFPR? It may be a bad vacuum source and its causing the RRFPR to act up... Did you just use the same vacuum port on the intake manifold that the stock FPR hooked up to? What line is your boost gauge hooked up to? Mine is just teed off the same line that the RRFPR is connected to. Some people said not to do that, but it hasn't caused any issues with mine thus far.

The AEM F/IC isn't as comprehensive as the GEMU is, and I'm not sure if it can control VTEC point. I have an Apexi VAFC Neo hooked up on my low-boost setup. It's not great, but its better than the standard Comptech ESM because I can make changes and control the VTEC point. I've been using it for a few years now when I was N/A and after installing my current setup. I just lowered VTEC to 5000 RPM and leaned out the upper RPM range as it was still running rich up there after adjusting the RRFPR. It is definitely a good compliment to the low boost CT setup.

I'm going to be selling it soon once I move to 12 PSI and go standalone ECU. Let me know if you are interested in it; I can help you with the install/setup and such. But let's get this issue resolved first!

 

The vacuum line is taped at the old fpr location.

And yes it is T ed just before the rrfpr to go to the boost gauge.

I will look into modifiying that just in case.

And voltage too

Its funny that my local tuner says that the f/ic is better them the gemu. He says it as a beter way to calibrate injectors duty. Something to do with % ???

Also is brother bought a used vortec sc and is walbro wasnt constant so he strongly suggest i change it before buying anything else. Even if he is right he wont tune my car. Pretty honest i guess.

No worries. We will solve that b... Of a problem

;-)

 

For what it's worth, the SOS base kit specs the fuel pressure of the RRFPR to be 58 psi at idle for the AP2 and hitting 88-90 psi at redline. I can confirm the AP1 specs when I get home, but those CT figures seem kind of low? I would imagine they should be similar as the kits are pretty similar?

And you're checking/setting the fuel pressure with the vacuum line disconnected from the RRFPR?

I wonder if you have the correct Walbro 255? There's a high pressure version, and a non-HP version. The HP version is the one you want. With that said, I think you have correct version based on the part number I saw in one picture.

 

Replace that Walboro pos with a FB or Aeromotive 340. You should be seeing around 90psi fuel pressure at redline. 60ish at idle.

DO NOT go with an AEM FIC, they are not compatible on our car. I made the mistake of listening to a AEM tuner years ago who tunes with the full EMS but never an FIC on our car and it was a nightmare that ultimately fuel washed my motor. A E-manage Ult actually works and is what I use currently. Problem with them is hardly any tuners understand them so they don't support them.

If your fuel system is working properly AND you actually have the proper size pulley on your car, neither of which I'm convinced of yet, the base comptech system can and will work reliably for you indefinitely. Don't get sucked into spending another 2k on engine management systems and the whole 9 yards to "fix" your issue, because it isn't necessary when you have an otherwise reliable and functioning set up at base pressure, if you can get to the bottom of the issue of why its running lean.

It would be nice for you to take a pic of the pulley your using along with a measurement and post it. Should be 4.4" Ap1 4.25" ap2. It would also be nice for you to take a pick of the RRFPR so I can see where its adjusted.

 

Your under boost pressure is lower than it should be, assuming this is at 6 lbs of boost around redline.

Either your RRFPR is not working properly, or your fuel pump is going bad.