fuel pressure question

[back2fox]

Just finished up with my H/C/I. Thumper, Tmoss, custom cam.

I have new fuel pump, holley adj regulator, stock injectors. I put it on the dyno with 40psi and the car was running 16:1 a/f mixture.

I had to turn up the fuel pressure to 50psi just to get a 13:1 a/f at WOT and it's still running lean at idle.

What would cause this???

 

[HISSIN50]

Given the lack of spefics, a lack of tuning (getting inside the puter, not WOT FP tricks) could be it. Other things like bad MAF input won't help.

Good luck.

 

[back2fox]

Ok, why would I have to turn up the pressure on the regulator just to maintain a decent a/f ratio? It was lean at idle and WOT with the pressure at 40psi. Now at 50psi it's ok at WOT, but is still lean at idle. I shouldn't need a tune with such a mild set up.

 

[Flavadave4]

Something else is the problem, a set up like yours (and mine) should run perfect in the 40-42 psi range.

I assume you were setting the fuel pressure on a warm engine at an idle with the vac line off?

MAF may not be functioning as it should.
Dump the codes and go from there.

 

[back2fox]

Thanks, I'll start there.