High fuel pressure

brif

Member
I just installed a new DW fuel pump and a new power master alternator. The alternator is set to about 14.6 volts. The problem I am having is I can't get the fuel pressure to less than 52. It doesn't move with the line on or off. Prior to this, the regulator was changing with the line on and off. We initially fired it up after the pump install (before the alternator) and the pressure wasn't as high as it is right now.

I have stock fuel lines and I suppose with the increased voltage I am getting problems. Do I need to change a return line? What happens if I drive the car with the fuel pressure this high?
 

87GN_70GS

Active Member
Your return is too restrictive for the higher flow of your new pump.

The effect will be that it will be richer in open-loop. The ECM will compensate once in closed-loop.
 

brif

Member
A really weird thing happened today. When i tried lower the fuel pressure, it wouldn't move and I cranked it quite a few turns and just left it there. I took the car out today and drove it awhile. I was thinking about putting on my fuel pressure transducer and popped the hood. Now the fuel pressure gauge read about 30 with the line on. I cranked it up to 43 with the line off and went for a spin. It seems to be maintaining it. Now my question, why would it change after taking if for about a 30 min cruise? i have the transducer that I can use to double check the gauge, but maybe a regulator issue. The regulator is an adjustable billet one (unsure of brand). If everything checks out I would be pretty happy, but I am a bit concerned. I checked a PL file and it's showing about 13.9-14v under boost.
 

Ttype6

Well-Known Member
A really weird thing happened today. When i tried lower the fuel pressure, it wouldn't move and I cranked it quite a few turns and just left it there. I took the car out today and drove it awhile. I was thinking about putting on my fuel pressure transducer and popped the hood. Now the fuel pressure gauge read about 30 with the line on. I cranked it up to 43 with the line off and went for a spin. It seems to be maintaining it. Now my question, why would it change after taking if for about a 30 min cruise? i have the transducer that I can use to double check the gauge, but maybe a regulator issue. The regulator is an adjustable billet one (unsure of brand). If everything checks out I would be pretty happy, but I am a bit concerned. I checked a PL file and it's showing about 13.9-14v under boost.

I learned years ago that I couldn't adjust my fuel pressure from a higher pressure to a lower pressure by backing off the adjustment screw until I reached my desired pressure. If I did this it wouldn't rise one to one with boost. I learned that I would have to back out the screw until the pressure was lower than desired then turn the pressure up from the lower to the higher. If I did it this way it would react to boost properly. When I would start turning the screw in to raise the pressure from the lower point I would have to turn it quite a bit before I could see the pressure start to rise. This is what you did so I'm thinking your good. Your gauge didn't suddenly start lying to you. You just learned what I learned years ago. Your good to go.
 
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