I just built up my LT1/LT4 383 with an ATI P1SC 8#.

During the dyno session, the AFR ran a pig rich <10:1 AFR from 2000 to 4500, where it then went waaaay lean.

I installed some LS1 28lb injectors and have LT1 edit. In monitoring the fuel pressure, it only spiked to about 55 lbs of pressure at the highest point.

It seems the FMU is wimpy (or the aux fuel pump). My tech wants to replace the injectors and dump the FMU. That's fine if I had another $1000 to throw his way. This is one of those guys that if I do the work, find some good injectors for $350 and install them myself, will fold his arms and say the problems are all mine now and go away.

I sense the FMU is not set right, I should be getting good pressure.

Also, I triggered a P0103 code each blast. (MAF high sensor).


Any suggestions to get the pressure up? Any suggestions to trim the rich condition during the mid RPMs.

Thanks,

UD

 

I would go ahead and dump the fmu as well and just get some 42lb injectors. If you plan on keeping the fmu which I would in your case because you have those injectors right now. I would turn up the fmu, its adjustable.

 

For sure ditch the fmu. 350 should get you some 42lb injectors and they take about 15min to install. Then you will need to buy a bigger pump GSS340 $109.35.

 

I didn't even use the FMU i got 38#'ers from the getgo. Tuning will be so much easier.