found that my 87 tpi 350 was running only 30 psi, i found the pump was weak, but it still was low slightly above 30 psi. So with return line pinched, i can now get over 70 psi. The problem is, if i jack the pressure up to 50 psi, i get a code 42. Doesnt make much since. As soon as its back down to thirty, the light goes out immediately. any help is appreciated.

 

Are you sure your vacuum line to your fuel pressure regulator is good? You must then have an adjustable fuel pressure regulator, is the regulator in good shape with no rips in the rubber diaphram? Your code 42 is a poor electrical connection on the electronic spark timing according to the book, make sure your plug is connected on the pass. firewall.

 

the line is good, i dont have an adjustable one, im looking to get one if i have to replace it. I pinched the return to get about 50psi with car running. It seemed more responsive at idle, but going down the road it seemed to have less oomph and i noticed it popping a bit out the exhaust. maybe 50psi is too high?

 

I'm not sure how your keeping 50 psi if you don't have an adjustable fpr, you can't keep the return line pinched to achieve this or you'll ruin your fuel pump. And yes you can run 50 psi but i wouldn't go any higher. Stock is set around 43.5. The proper way to check your fpr is to disconnect the vacuum line to the fpr with a gauge on the schrader valve.