okay someone please help me. i have a vortech sq just installed it in my 96ss. the fmu that came with the kit was stuck so i put on a different fmu, under full throttle the fuel pressure spikes all the way and the car just about dies off. what can i do what do i need to do. should i say the hell with the fmu and use the fuel pressure reg.


help me please

 

If you have big enough fuel pump and injectors say 50LB er's you can ditch the FMU. I think it's easier to tune without it. If you are using stcok fuel pump and injectors I would stick with the FMU. There should be an adjusting screw on the FMU for tuning.

 

i have a 255 in tank and the t in line, using stock inj. do you think that the screw is f**** up because the fuel spike is nasty style as soon as the car goes to wot it spikes but under normal accleration the car is fine

thanks for your help just looking for some more feedback. to get this car running the right way.

 

Not much information ... but ... if you are running stock injectors, 24#ers I believe ... you should be seeing around 75 - 80 psi on the very top end of your 6 psi of boost. More than that and you are probably rich and drowning in fuel. You are looking for an A/F ratio of around 12.

Just a guess, you really should get it on a wide band dyno and with an adjustable FMU ... it is easy to sort out in about half an hour.

Might be your ignition, spark being blown out ... lots of things can go wrong ...

Dyno it ... wide band, they can sniff the fumes ... will tell you a lot ...

Hope this helps

LWM

 

LWM- I don't have much experience with FMU's, but if he is seeing 80lbs fuel pressure, than it's likely his stock injectors are locking up (completely cutting fuel).

A switch to a pintle type injector would solve this problem, but if money is going to be invested in injectors, an upgrade to 42.5's and custom programming would be the best solution.

 

You may be right ... though I ran my 6# kit for a while with stock injectors. I didn't really consider the stock injectors locking up under higher fuel pressures that the Vortec kit would entail, you'd think that the S/C kit would harmonize with the stock injectors ... or else they would put that information down in black and white.

Anyway, SVO type injectors are definitely recommended.

With 42# injectors, he should be able to do away with the FMU. I'd recommend the LT1 editor ... only because I have it, for tuning with the bigger injectors. Tuner cat I hear works just as well and may be less expensive.

Hope this helps

LWM

 

I am running 38# injectors with an inline T-Rex with a Walbro 255 not installed yet. With the T-Rex and 38# I have 0 fuel issues with no FMU installed.

 

How is your idle with those injectors and programming without the FMU?

 

my idle was fine after a couple of mins on the phone with vortech we found out that the fmu for some strange reason had a 12 pound disc in the fmu, well that is just a little to rich so we overnighted the 8 to 1 that is supposed to be in it. i will get the disc on wed and let every one know how she is doing.

thanks for everyones replies man i love this board i'm glad i can be on it I NOW BELONG TO THE DARK SIDE(and the soon to be rebuild club go figure)

see you all at the trak thanks again
tim