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4.0 fuel pressure

1K views 5 replies 4 participants last post by  Marty, SoCal 
#1 ·
Do all 4.0s need the same fuel pressure? Or is there a difference between obd1/2 or different years? I have a '00 going into a cj.

I'm trying to decide whether to use an inline pump and regulator with the stock cj tank or try and make a yj or tj tank with the in tank junk work.
 
#2 ·
AFAIK they're all the same, 40psi out of the pump. I have the Hesco MPI kit
on my 1986 CJ7 4.2L and it uses their inline pump mounted externally to the
stock CJ tank. There's a fuel filter between the tank and the pump.
 
#4 ·
Use a WJ fuel filter, it has the correct pressure regulator (50 psi) and return line built in, perfect for a 2000 4.0l. It's also externally mounted, where a TJ or XJ regulator is in the tank mounted pump module.

As to pressure, there were some changes, basically, the fuel pressure spec changed with different injectors and controllers, so figure out which controller you want to run, match the injectors to that application, then be sure the fuel pressure is correct for that setup.

About 10 psi over stock sometimes helps when you are doing a 4.0l EFI and head swap on a 4.2l.

Hope this helps!
 
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