On my 95 4.9l, I have changed out my 12# injectors with 19# injectors. I also change the pressure reg to an adjustible. I also have tried a 5.0l regulator as well. I can not seem to get the pressure low enogh. It runs really rich. When you turn the key on I get 40 psi but when I start it I get 80+PSI. What all do I need to do to complete this mod? Any help?

 

I'm pretty sure your motor should have 19lb injectors(orange top) and the fuel pressure should be 50psi without vacuum and engine running. There really is no need for an adjustable regulator on this motor... or larger than stock injectors either, but if you cannot adjust the pressure down that much then you have an obstruction in the fuel system.. kinked return line or clogged check valve in the fuel deliver module inside the tank.

 

It did have 12#(white) injectors from factory w/ 55-60 psi press. the blockage may be an issue. I have not used the other tank since I changed the injectord to 19#(orange). Thanks I will look at that.

 

It should run really well at 40psi with the 19lb injectors. Make sure you coolant and air temp sensors measure within spec. Assuming your truck is speed density opening up the exhaust will lean it out some too.

 

I meant to expand on the injector thing. You can't just install larger injectors and expect it to run right.. especially with an SD setup, the computer is programmed around the stock injectors and anything else will mess up the calculations and make it run badly. With MAF you can utilize larger injectors with a matched MAF meter but this isn't perfect either and the further you go from stock the worse the results.

 

Why is the OP installing larger injectors to begin with?

 

I went with 19lb on my 1990 and ran 40 psi. It runs sweet and easier on the fuel pump. 300's run really lean anyways the the 12lb injectors at 60psi it is more like is more like 18lb injectors so its really not that much more fuel.