Hey guys, been trying to get my fuel pressure set correctly for a while on my '89 Caprice but am having a problem. For starters I have installed a TPI pump. I have borrowed an older Snap-on fuel pressure gauge and inline adapter. The inline adapter is installed on the supply line (this is right by the AIR pump). I have installed the adjustable regulator off my the BB TBI I bought. It has an allen key to increase or decrease the pressure. However, no matter how far in or out I go the pressure does not change. It stays a steady 16 PSI. What gives? Do I need to pinch/block off the return line to get a correct reading? Does the car need to be running? I've done most of my adjustments with the car off and fuel pump relay bypassed.

 

If im not mistaken thier may be a maximum setting. and it could be 16. I bought and have not installed a holley tbi for my car. it came with a 30 lb spring ont he side. So im assuming you have to change the springs to get different fuel pressures. I could be wrong. The spring you have may be good up to 16 and then maybe you'd need a different one for more than 16 psi. Again I could be wrong.

 

I'm actually trying to go back down to the stockish setting 12 or 13 PSI.

 

some BB TBI units(like my 1994-1995) are run at high pressure >20 lbs. I think the spring was orange? Can you swap in the spring from the former GM reg in Caprice? If not topdownsolutions sells a spring for like 12-18 lbs.

 

I used the stock spring in the adjustable reg. I believe it was orange.

 

YEP, 20-50 lbs....

 

Year and a half later I finally got this figured out. Car has been sitting for well over a year now and it is time to sell it. Wanted to get the fuel pressure sorted out as I will be removing the EBL and putting a stock ECU back in it. Ronny was right, it was the spring (orange). I replaced it with one out of a L03 TBI, I believe the spring was yellow. Made the stock FPR adjustable as per this method. Finally got my pressure down to 13 PSI.

 

FYI top down solutions has a spring just a tad stronger than the stock one you are running now. If you are holding 13 you are OK. If you chose to go higher on FP look to top down

 

If you still have the spring, this is where it goes.

https://www.thirdgen.org/forums/tbi/...-injector.html

Twisting the adjusting screw anchor in the regulator body as described in the linked post often results in the anchor coming loose disabling the regulator completely. Take your chances, or do it right and drill loose the adjusting screw.