vp44

It is a well known fact that the weakest link in the 24V 1998.5-2002 motor is the vp44 injector pump. The concept of having an electrically controlled injector pump sounds good and definitely makes for a more pure combustion due to it’s precise controls, however, somewhere along the lines Cummins dropped the ball on this one. Several reasons make the vp44 prone to failure.

Perhaps the most common flaw with the vp44 is the weak lift pump that came on the stock trucks. The lift pump was not strong enough to keep pressure to the injector pump which causes the housings to wear out causing the front diaphragm to fail. In addition to this, Cummins designed the fuel to act as both a lubricant and a cooler. The lubricant factor doesn’t work because the EPA has now outlawed high sulfur diesel which was standard when the engine was created and actually has lubricating power unlike the new low sulfur diesel. The cooling factor of course would be reduced if the volume of fuel was low due to a bad lift pump. The heating rises another issue which is the second major flaw with the injector pump. The fuel control computer is located right on top of the pump which is located right on the engine. Over time the heat of the engine causes this computer to slow down due to a crystallizing of the electronic components.

So, this sounds like a fairly desperate situation… what are we to do?

There are a couple options.

The P7100 mechanical pump on the older trucks can be swapped in place of a vp44. You do loose your electric control of the pump as well as a huge chunk of change. On top of buying a p7100 you would also have to buy about 1K-2K worth of modification parts just to put it on there. However, some people think it is well worth it and take this plunge. The p7100 is a bombproof pump which is oil lubricated and cooled. The mechanical reliability of this pump make it the pump of choice for those who modify their truck to the max.

You can replace the vp44 with an upgraded version and add a fass or airdog fuel pump. Blue chip diesel offers a specially made vp44 which has an updated computer as well as a super build job which gives 2-3 more MPG’s. Blue chip also sells a remote computer for controlling your fuel system which bypasses and overrides the computer on the pump itself. Blue chip has pretty much devoted their company to fixing this vp44 problem as well as making some other sweep parts for 1998.5-2002 Cummins motors.



I am fairly confidant that my vp44 is on its last leg. I sometimes get the dead pedal effect which is a sign of a failing vp44. When I finally get around to addressing the problem (when I have the money), I am planning on purchasing the blue chip vp44 with an air dog lift pump. Also, another sign your vp44 is failing is reduced fuel economy… and I’m getting about 3 mpgs less than I should.