The most common
mechanical failure of the VP44 pump is rupturing of the diaphragm
in the front of the injection pump. The diaphragm ruptures allowing
the timing piston to vibrate and damage the front cover until fuel
bypasses. This will cause the dreaded check engine trouble code
P0216. When this occurs your Bosch VP44 Injection Pump must be replaced.
The rupturing of the diaphragm is caused by a poorly designed lift
pump. When the lift pump does not supply the Injection pump with
the correct amount of Fuel Pressure (a minimum of 5psi under load
at wide open throttle) the diaphragm then doesn’t have enough
positive pressure and ruptures. Dodge has recognized this problem
as they will no longer even sell the lift pump that goes on the
side of the block, they replace it with a unit that is now mounted
in the tank. The average cost of having the lift pump put in the
tank is about $800.
The next most
common mechanical failure of the VP44 is that the rotor seizes in
the head of the pump. This again can be contributed to the lift
pump not providing enough fuel to the injection pump. Diesel Fuel
is used as a lubricant , so when there is a insufficient amount
of fuel the rotor does not get lubricated properly. If the rotor
seizes the truck wont start and the VP44 Injection Pump must be
replaced.
The last reason
for the failure of the VP44 pump is electrical problems with the
computer on top of the pump. Heat is the main reason associated
with this problem, causing the soldered components to become crystallized
over time and make bad connections. Lack of fuel is again part of
the problem, because the VP44 is cooled with fuel instead of oil
(as the old P7100 12valve pumps). When this problem occurs you will
usually experience intermittent hard starts, white smoke and what's
usually referred to as “The Dead Pedal”.
