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Changing out the OEM lift pump on my 02 Journey and was shocked to find that the OEM fuel hose on the pressure side of the lift pump was 1/4" Cummins calls for a minimum of 3/8" hose to the Cummins ISB engine with the VP-44 injector pump. I now understand why the carter OEM pumps don't do a good job, having to push a substantial volume of fuel under pressure thru a 1/4" hose. I guess Winnebago saved a couple of bucks reducing the hose size, by the time you need a VP-44 pump the vehicle is out of warranty, of course. This is distinctly Winnebago"s doing, as the chassis delivered from Freightliner does not arrive at Winnebago's factory with the lines to the rear mounted fuel filter water separator. Winnebago installed all the filter/seperator related hoses. If you have a 02 ISB, I would strongly recommend that you install a pressure gauge on the output line from the water separator/filter to the VP-44 injector pump, you must maintain a minimum of 9-10 psi WOT, if not you will be buying a $2000 min. pump very quickly. The VP-44 relies on fuel moving thru it for it's lubrication and cooling. When the pressure drops below 4-5 psi you are wearing out the pump. Most OEM carter pumps barely put out 5-8 at an idle. You also should know that if the lift pump fails, completely, the engine will still start and run. When the lift pump fails, the VP-44 will then draw fuel thru the lift pump and there will be a suction on this line instead of pressure. The Carter lift pump is a diaphragm pump and it will allow the IJ pump to draw fuel thru it even if inoperable. This situation can go on for some time without significant performance issues or before the eventual VP-44 failure from lack of cooling and/or lubrication. Word to the wise: CHECK THE PRESSURE ON THE LINE TO THE VP-44 INJECTOR PUMP!!!!