running lean!

**93camarolt1m6** · 01-01-2015, 05:32 PM

i am runnin lean on both banks my tuner asked me to check fuel pressure but i just installed a walbro 255 fuel pump, filter and regulator as preventive maintenance and i am stumped to why ask when he knows what all i have done. could a vacuum leak cause a lean condition, datamaster v5 shows it to be in the ideal mixture some of the time but when getting on it or taking of normally and driving normally it runs lean. it a 1993 camaro lt1 m6 with air foil, k&n cold air, bbk shorties with bbk ory into stock cat and edelbrock cat back. i also have a manual exhaust cut out after cat but checked its not leaking besides it does not have after cat o2 sensor anyways. any help besides checking fuel pressure due to not having gauge for another week christmas killed my savings.

**sweet-94z28** · 01-01-2015, 11:16 PM

You could have a few different issues. Are the BLMs correcting the air/fuel at part throttle? Do you know what they are reading by chance? Also, this could be a vacuum leak but since you don't have a MAF on a 93 it's a little harder to tell as it won't throw a MAF code. How old are the main o2 sensors? Do you maybe have an exhaust leak at the header/y pipe connection? I would still verify fuel pressure though to make sure you have enough at the rails. Fuel pumps can be bad right out of the box.

**93camarolt1m6** · 01-02-2015, 12:19 AM

well im going to autozone to borrow their fuel pressure gauge in the morning. i have checked my header install for leaks and i have found none. the o2's are new delphi i put them in with the headers to cover base. as far as vacuum leaks im going to get some starting fluid and spray down all vacuum lines to check.

**sweet-94z28** · 01-02-2015, 01:19 AM

Spray down the injector o-ring areas and where the head meets the intake as well. Is 1 bank leaner than another?

**93camarolt1m6** · 01-02-2015, 09:56 AM

just a tad bit. i dont know if it is the tune or actual problems i sent him my log run if you have an email i can send it to you if you have datamaster v5

**sweet-94z28** · 01-02-2015, 11:00 AM

Send me a log and I'll take a look. mickelsonperformance@yahoo.com

**93camarolt1m6** · 01-02-2015, 02:12 PM

so i checked fuel pressure with vacuum it was at 48 idle/wide open with vacuum its 42 idle/wide open at wide open. also sprayed all vacuum lines and injector bases and nothing so i send a video of fuel pressure readings and my log file. im glad its just in the tune i think.

**93camarolt1m6** · 01-13-2015, 10:15 PM

finally solved! even though spraying starter fluid didnt point any vac leaks out i started with my injectors, i replace the o ring and the regulator and fired it up at that point. to my surprise no more lean condition and the vibrations at part throttle in 4-6th gear gone. the o rings we totally dry rotted and the regulator tested fine but changed it anyways. im happy i solve 2 things in one shot.