i got a 93 f150 4.9l 4x4 5sp with 127,000 miles. and i had recently put 20# injecotrs in my truck cause i thought when i asked people they said stock injectors were 19# and now i did some research online cause my truck is running rich, and found that stock fuel innjectors are 12#.

-an i get more power out of my truck if i buy an adjustable fuel pressure regulator and make it so it isnt running rich? and if so can any1 help point me to a good one online for my truck cause i cant seem to find any.

 

Your PCM needs to be reprogrammed to adjust the fuel delivery strategy to compensate for the higher delivery rate of the new injectors.

Apparently, the feedback signal from the HGO sensors is being overwhelmed by the amount of fuel injected since the "on time" of the injectors is tuned to an injector delivering a lower amount of fuel per unit time. Monkeying around with the fuel pressure will not change the situation since the strategy is within a feedback loop that will cancel out any change in fuel pressure; eg., the lower the fuel pressure the longer the injector will be held open.

The foregoing is my best guess as to the cause of your problem.

 

ok i will put old injectors back in.

 

if i reprogram my truck for the 20# injectors would i maybe have a little more power or should i keep the 12# for mpg, or would the 12# probably be around the same power?

would it be hard to reprogram the injector part of the computer. i do know a little about computer stuff. if i would do this i would actually go to a junk yard and get a test ecu so i have mine for backup.

 

Unfortunately the higher rate injectors won't return more power unless you can find a way to increase the amount of air the engine will pump.

Changing the PCM strategy requires a reflash of the memory. It's best done by a pro or at least someone really competent in the technology....generally not suited to the capabilities of the average shade-tree guy.
Perhaps, however, a PCM from a HiPo engine might work providing all the accessories or their equivalents from the HiPo system can be transferred to your ride.