car runs lean...

[90mustangfan]

how can I test the stock fuel pressure regulator to see if its bad or not?

 

[emagdnim]

how can I test the stock fuel pressure regulator to see if its bad or not?

Hook up a fuel pressure guage and see what your pressure is.

 

[notchback]

yup like he said...i would run it hard too , to see if drops or anything...you can tap into the schrader valve and just hold the guage outside the window if you don't wanna mount it...there cheap ones you canmount right on the rail, but obviosly you can't see it driving

 

[dilligaf]

would a bad fuel regulator make my car idle up and down?
I have a pressure gauge but the pressure is never the same. One minute it will be at 35, the next 30, then 38. And sometimes the pressure will change when i take the vac. line off, sometimes it won't. Sometimes it will change by 2# other times 4#. I'm pretty sure its bad, but my car has this idle problem and was wondering what the odds are that a new regulator might help.

 

[jrichker]

See the sticky "Help me create the Surging Idle Checklist" at the top of the forum for help with your idle problems.

 

[Zero_chance]

I would run the checklist before you start getting eager t oswap out parts. The pressure should change when you disconnect the vac line.