Hi I have a 1992 ford motorhome with a 7.5 superduty engine I have replaced fuel pump not assembly just the pump and the filter. My motor home cranks up and gets 32 psi at crank up remove the vacuum to the regulator and goes to 40 psi. With vacuum on you pressing the gas or taking off you it rises from 30 to 40. After driving a half mile the pressure will drop while just pressing the gas or taking off the pressure goes from 30 back to 20 and after this happens you can kill it for a split second and the pressure will go back to acting normal. But after that every time you crank it the pressure will not go back to normal but it will go from 30 to about 32 then soon there after it will go back to dropping back to 20 while hitting the gas. And it makes no diffrence with the vacuum line off besides it will go from 40 to 30 psi while pressing the gas. And one thing I did notice was when you crank it back up and pump the brakes it felt spongy and the first rev would go from 30 to 32 but go to from 30 to 20 every time after just thought it was weird.
Tuesday, December 4th, 2012 AT 12:11 AM