my fuel pressure never goes over 60 and that was at -20 VAC. As boost increases fuel presser drops. I hit 3.8 PSI Boost and my fuel pressure dropped all the way down to 3.5 PSI, well guess that it why the engine is cutting out... No fuel.

Its gotta be the FMU or I don't have something connected correctly.

 

ok i pulled out the fmu and took the lid off to expose the metal button (where the vac line connects to pressurize under boost) and pressurized the input line with air when I pushed the button it cut the air off at the fmu.

I thought the FMU increased pressure as boost increased, but the way it's set up it is decreasing pressure by closing the line.

Can I just remove the FMU?

 

ok now I removed the FMU completely and have a direct connection from the tank pump (walbro 255) and the damper.

I peaked fuel pressure at about 58 PSI, averaged 50 PSI, and my lowest was about 48 PSI. I am still running lean. I don't understand. here are the logs:

AFR WB-B1 (AFR) AFR WB-B2 (AFR) CAL/LD VALUE (%) ENGINE RPM (rpm) THROTTLE POS 1 (V-Throttle) VEHICLE SPEED (mph)
11.42 11.79 100 4413 4.17 40.4
11.6 11.64 100 4525 4.17 41.3
11.69 11.76 100 4650 4.17 42.2
11.31 11.49 100 4763 4.17 43.3
11.61 11.7 100 4875 4.17 44.4
11.79 11.83 100 5050 4.17 45.4
11.96 11.91 100 5188 4.17 47
12.36 12.11 100 5288 4.17 48.2
12.36 12.72 100 5463 4.17 49.5
12.67 12.9 100 5563 4.17 50.5
12.85 13.06 100 5750 4.17 52.2
12.34 13.44 100 5925 4.17 53.6
13.44 13.53 100 6088 4.18 55.2
13.3 14.14 100 6238 4.17 56.7
14.48 15.23 100 6325 4.18 58.1
14.46 14.44 100 6488 4.17 59.2
15.32 15.84 100 6575 4.17 60.4
15.77 16.69 100 6638 4.17 61.4
16.5 16.31 100 6700 4.17 62.2
16.35 17.06 100 6813 4.18 62.7
16.5 17.19 100 6813 3.39 63.5
16.69 17.02 100 6875 4.17 64
16.9 17.5 100 6950 2.53 64.7

Ouch that's lean - 16.5 full throttle 100% load. I figured I would be running really rich at this point.

 

your not getting enough fuel pressure, with no fmu. have you seen the mod they do on the turbonetics kit with the fuel regulator in the fuel pump assembly, where they drill the hole on the regulator alittle bigger. you got the bigger fuel pump but that regulator doesnt let sufficent fuel pass through. i think that should fix your problem.

 

no, I have not. time to search

 

something is not working properly. i have seen probably every fuel issue there is now. haha


make sure the vacuum lines are all connected good and tight and everything looks 100%.

good luck

 

what PSI should I be seeing with the walbro?

I am going to do the regulator mod harogts is talking about.

 

i sent you that manual. hope it helps, let me know how it goes

 

I found this from the following thread (from Sharif@Forged) https://my350z.com/forum/showthread....rmance+Factory
I'm seeing 52 PSI at Idle without the TN mod. Also, if I do the TN mod without a ECU re-flash will it have problems?

 

i wouldnt think you need a reflash your piggyback takes care of it.

 

research somemore on tn mod, i wasnt aware that you cant buy that regulator alone you'd have to buy the whole assembly if something goes wrong$$$i know theres other people with vortech that removed the fmu and droped in a walbro. anyone with that setup alittle help over here

 

ok here is the current plan. I picked up a UTEC from SGP and some 440cc injectors and waiting for the clips from Forged. Gonna install the injectors and the UTEC and get a base vortech map from SGP. Then I will take some easy runs and do some logging. If I am not running way lean anymore I'm taking it to SGP to tune.

Sheesh I wish I would have bought a tuner kit

 

good stuff, let me know how it goes. im planning on switching to utec also

 

I had this same problem. My tuner (also here in Houston) and I were puzzled for an entire afternoon.

The issue is that the stock vortech tune on the unichip is locked so all tuners have to start from scratch. What many tuners don't know is how to engage the unichip to activate the auxiliary fuel pump. This is under "Option 5" in their unichip tuning software and they have to turn it to "On/Off Cam Control". From there there are a variety of values that they can set to turn that on or off.

We spent an entire afternoon with the same problems that eez had. Luckily we had so many helpful other folks from JE Import in Maryland to the nice folks at Vortech to the folks at Unichip.

Once that was figured out our tune went smoothly.

I hope this helps anyone else who comes across this thread later.