lift pump failure Cummins 98'-02' Fuel Lift Pump Warning

[rlbarkleyii]

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!!!!

 

[dickandlois]

The Carter lift pumps on the RV Chassis using the Cummins ISB should have been replaced with the Cummins 4943048 Vane style Pump. They last somewhat longer then the Carter pumps. 

I'm at a point where the current Cummins pump pressure is falling below the recommended min pressure of 5 Psi at the VP-44 injector pump. So after less then 100 K miles on 3 Cummins pumps it is time to invest in a FASS DDRP series lift pump that is a direct bolt up unit(it hangs horizontal instead of vertically), but the catch is the fuel supply line parts kit is set up for 3/8 in. lines used on the Pickup trucks and the Freightliner chassis uses I.D. 1/2 in. supply line, so the proper adapter needs to be installed on the intake side of the pump and then the output side is (as mentioned by rlbarkleyii) a 1/4 in. line feeding the injector pump.

The Fass pump supplies 110 GPH at around 15 PSI under load and also has a 4 year guaranty as long as you follow their requirements concerning the insulation. 

AS a heads up Cummins is now supplying a single piece line that runs from the lift pump to the injector pump, Part # 3948116 to replace the 2 steel line sections and the rubber hose connecting to 2 short sections.

Rich.

 

 

 

[desertdeals69]

I just installed a second 90 gallon fuel tank and a Air Dog lift pump with a 1/2 inch fuel line.  It is capable of pumping 150 gph and supplies 15 psi to the injector pump.   I also changed the VP44 injector pump as the new to me 98 Discovery had been run without the lift pump functioning.  I drove it 1900 miles last week and it ran good.

[wildebill308]

Where did you find room to install a second tank?

Bill

[jleamont]

18 hours ago, DickandLois said:

100 K miles on 3 Cummins pumps it is time to invest in a FASS DDRP

Rich, sometimes you just have to step it up and get rid of someone's else's bad design. Its unfortunate when the end user/consumer has to fix a large chassis/engine manufactures poor planning and execution. I truly believe this was all created by lack of communication between manufactures, its becoming worse as technology advances.I don't blame you one bit, none of us enjoy sitting on the side of the road anticipating the repair/tow invoice. I was amazed when Cummins told me their pump was not designed to pull fuel that distance.

[desertdeals69]

11 hours ago, WILDEBILL308 said:

Where did you find room to install a second tank?

Bill

I moved the center mounted propane tank back one section and moved a cross member ahead 6 inches and it fit perfect.  I will be at the Chandler FMCA in March if you want to see the installation.

[desertdeals69]

11 minutes ago, jleamont said:

Rich, sometimes you just have to step it up and get rid of someone's else's bad design. Its unfortunate when the end user/consumer has to fix a large chassis/engine manufactures poor planning and execution. I don't blame you one bit, none of us enjoy sitting on the side of the road anticipating the repair/tow invoice. I was amazed when Cummins told me their pump was not designed to pull fuel that distance.

Its not only the rv industry but the main reason that FASS and Air Dog were developed was the need for help on Dodge pickups with Cummins engines and they only have a few feet to pull fuel.

 

[jleamont]

2 minutes ago, desertdeals690 said:

Its not only the rv industry but the main reason that FASS and Air Dog were developed was the need for help on Dodge pickups with Cummins engines and they only have a few feet to pull fuel.

 

Exactly, its not designed to pull it that distance either. On a med/heavy truck the tank is within 2-4' of the pump. 

[wildebill308]

12 minutes ago, desertdeals690 said:

I moved the center mounted propane tank back one section and moved a cross member ahead 6 inches and it fit perfect.  I will be at the Chandler FMCA in March if you want to see the installation.

Yes that would be interesting.

Bill

[jleamont]

Just now, WILDEBILL308 said:

Yes that would be interesting.

Bill

Any idea how much weight you had on the chassis before and after? Just curious since most are close or often overloaded, adding 600 + lbs could get interesting.

[desertdeals69]

1 hour ago, jleamont said:

Any idea how much weight you had on the chassis before and after? Just curious since most are close or often overloaded, adding 600 + lbs could get interesting.

I don't know.  Its only a 36 ft so I should have plenty of capacity.  I am going to weigh it the first chance I get.  It drives great.  I just did my maiden trip of 1900 miles to Indiana to the paint shop and left it there until the 2nd week in Jan.