Ok, so having a problem with up towing stumble when under load. I have 98 454 "j" 26wu Itasca on the last year that chevy produced it's P30 chassis. This stumble has been a real bummer, I checked the fuel pressure when the vehicle was new and it showed 52psi. I added an additional gas tank and it dropped due to the switch over valve to 50psi. shop manuel says 56 to 62psi. But I have driven it 120k with the 50psi with no problems. Checked recently and it has dropped to 48psi. Changed the Fuel Pressure Regulator to a stock napa unit, and got the reading of 46psi. Huh?????
Turns out the original unit is adjustable. They also make the fixed 50psi unit and also a 56psi unit for chevy trucks. Been trying to find one of the original units, so far no luck. Due to the length of the fuel lines and fuel switch over valve, the 56psi unit will show only 54psi, which is still below factory specs. So, turns out these adjustable units are what they used to adjust for the fuel line length and supposed to adjusted by the manufacturer. Duh.... needless to say, they were mostly not....
Yes, I changed out the fuel filter and fuel selector valve. Both pumps are showing the exact same pressure at the engine, so it is not the pumps. The only way to get the Fuel pressure to specs is to get the correct FPR that that is pre-set to 65psi to allow for fuel pressure drop or find and adjustable one. Any suggestions as to a source for the correct FPR?
May your black water hose never break! Life Charter member since 89
