fuel pressure question

back2fox

Member

Oct 7, 2006

73

0

6

Apr 5, 2007

#1

• Apr 5, 2007

• #1

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

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

34

129

Apr 5, 2007

#2

• Apr 5, 2007

• #2

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

Member

Oct 7, 2006

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0

6

Apr 5, 2007

#3

• Apr 5, 2007

• #3

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

Active Member

Nov 28, 2003

1,044

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Utica, NY

Apr 5, 2007

#4

• Apr 5, 2007

• #4

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

Member

Oct 7, 2006

73

0

6

Apr 5, 2007

#5

• Apr 5, 2007

• #5

Thanks, I'll start there.