Attention: TDR Forum Junkies I thought this was a good reply from Cummins to my question. Summary: ram isb lift pump concerns
Solution:
Thanks for your email Steve. You will have to speak with Dodge about
their plans to address lift pump issues in their vehicles; we have
different configurations, fuel system interfaces and filtration for various
applications of the ISB - including no lift pump at all. The latter
case is where there is sufficient "head pressure" and low restriction of
fuel flow to the VP-44 Bosch pump.
Also, the lift pump supplier, Federal Mogul, has been through a few
iterations of pump design; you might to well to procure one of the latest
configuration pumps as a back up. If you feel strongly that the pump
is an inpending or incipient failure mode it would be a good idea to
have one; at a minimum you'll be able to assist other Dodge ISB owners on
the roadside - we don't feel that this is necessary. The latest ISB
lift pump which supercedes previous and has all of the latest rev's and
seems to be working well in the field is P/N: 3990105.
One concern in general, and in particular with respect to remote areas,
is fuel quality. If you have reason to suspect marginal fuel quality
(a cause for many lift pump failures) and routinely drive in areas where
this is possible, you might work with the local Cummins Distributor to
add supplemental filtration to your unit. In other markets for the
ISB, primary filters are used in conjunction with the secondary one used
on your Ram truck. We do not specify this as an Application Engineering
Bulleting requirement for the ISB in Ram applications; then again, we
do specify, clean, contaminant and moisture-free premium #2 diesel fuel
... . we do recognize that fuel of adequate quality is not always
available.
The lift pump issue is important, because a failed or failing lift pump
can cause contamination to reach the VP-44 or can cause negative
pressures at the inlet to the VP-44 high-pressure electronic Bosch injection
pump; such can damage the pump through several different failure
mechanisms. The VP-44 is lubricated by the fuel, and sufficient fuel of high
quality is necessary to protect it. There were initial problems with
both the lift pumps and the VP-44; both have been upgraded and many
upgrades, changes and improvements were incorporated by the time your
engine was built.
Some customers have also installed pressure gauges on the outlet of the
lift pump and ahead of the injection pump, to verify positive pressure
to the VP-44; this is all well and good, but does present another
failure mode and additional fuel leak path opportunity, and we do not feel
that such monitoring gauges are necessary. Clean, contaiminant and
moisture-free fuels are necessary, and this should be your main concern.
Here is some more information on the VP-44: The VP44 is a
radial-piston pump with 3 pistons. The pistons are attached to the distributor
rotor and the fuel pump shaft. The pistons ride inside a cam ring (think of
a donut with a "bumpy" hole) so as the pump shaft rotates the piston
carrier, the pistons are compressed towards the center, pressurizing the
fuel. The pressurized fuel is then directed to the proper cylinder by
the distributor rotor.
The cam ring can be rotated in a "retarded" or "advanced" direction;
this is done using a solenoid valve, which modulates pressure to a
fuel-pressurized piston beneath the cam ring. Also, the start and end of
injection are controlled by a solenoid valve.
Although the VP44 was initially not as reliable as we would have liked,
Cummins and BOSCH are confident in its reliability today. The VP44 is
much less complicated internally than the P7100, and it has many fewer
finely machined parts. We don't know for sure that BOSCH considered
low-sulfur fuel when designing the pump, since the pump is fuel lubricated
and today's fuels are low-sulfur.
The VP44 is completely fuel lubricated, as the VE pump is. It does not
use oil lubrication like the P7100 does. The VP44 is expected to last
at least a long as the P7100 in normal automotive applications. However,
we obviously have much more "long-term" experience with the P7100 than
we do with the VP44, so our knowledge base is still evolving. Soon
after launch, the VP44 had its share of problems, just as the P7100 did
when it was introduced, but we have worked closely with BOSCH to correct
the issues with the pump, and we're confident that the VP44 will be a
reliable fuel pump.
Fuels with low lubricity can cause increased wear or seizure of the
VP44 fuel pump internal components. If you are not sure of the fuel you
use add a lubricity additive is required.
In March 2000, we contacted Bosch and they advised us that the
so-called "B-10" life of the VP44 is 2000 hours at full fuel rating. In other
words, If a pump were operated at 100 percent rated horsepower for 2000
hours, only 10 percent would fail; 90 percent would be okay. As the
typical duty cycle of the Dodge Ram is considerably less than this, the
expected life expectancy is considered more than adequate to meet the
needs of the Dodge Owner
The electronic controls on the 24-valve engine allow Cummins to control
the power and torque very precisely across the entire RPM range. The
mechanically controlled engines have their power and torque precisely
controlled at torque peak and rated power RPMs, but between those two
engine speeds, power and torque can often exceed the published figures.
Do be sure you use quality filters and fluids. We have found their
greater initial investment to be a good idea and to actually lower the
total cost of operation per mile, or hour. Cheap filters are a poor
investment.
Enjoy your truck and drive it anywhere you want to go. It should do you
a good job. Take the other actions as appropriate given you fuel
quality and sensitivity about "mission disabling failures. "
Thank you for choosing Cummins power or products. Please let us know if
you need assistance in locating the nearest Cummins-authorized
distributor or dealer. Please feel free to use our International Dealer
Locator: (http://www.cummins.com/partserv/intro.html) found on the Customer
Assistance page of the Cummins website (www.cummins.com).
Let us know if have other questions, or if away from your computer,
feel free to call us (toll-free, from North America) at 1-800-DIESELS
(343-7357), or 1-812-377-5000 (toll call, worldwide, ask for 800-DIESELS).
Regards,
--
Powermaster
Customer Assistance Center
Cummins, Inc.
Columbus, Indiana, USA
Email: -- email address removed --
Solution:
Thanks for your email Steve. You will have to speak with Dodge about
their plans to address lift pump issues in their vehicles; we have
different configurations, fuel system interfaces and filtration for various
applications of the ISB - including no lift pump at all. The latter
case is where there is sufficient "head pressure" and low restriction of
fuel flow to the VP-44 Bosch pump.
Also, the lift pump supplier, Federal Mogul, has been through a few
iterations of pump design; you might to well to procure one of the latest
configuration pumps as a back up. If you feel strongly that the pump
is an inpending or incipient failure mode it would be a good idea to
have one; at a minimum you'll be able to assist other Dodge ISB owners on
the roadside - we don't feel that this is necessary. The latest ISB
lift pump which supercedes previous and has all of the latest rev's and
seems to be working well in the field is P/N: 3990105.
One concern in general, and in particular with respect to remote areas,
is fuel quality. If you have reason to suspect marginal fuel quality
(a cause for many lift pump failures) and routinely drive in areas where
this is possible, you might work with the local Cummins Distributor to
add supplemental filtration to your unit. In other markets for the
ISB, primary filters are used in conjunction with the secondary one used
on your Ram truck. We do not specify this as an Application Engineering
Bulleting requirement for the ISB in Ram applications; then again, we
do specify, clean, contaminant and moisture-free premium #2 diesel fuel
... . we do recognize that fuel of adequate quality is not always
available.
The lift pump issue is important, because a failed or failing lift pump
can cause contamination to reach the VP-44 or can cause negative
pressures at the inlet to the VP-44 high-pressure electronic Bosch injection
pump; such can damage the pump through several different failure
mechanisms. The VP-44 is lubricated by the fuel, and sufficient fuel of high
quality is necessary to protect it. There were initial problems with
both the lift pumps and the VP-44; both have been upgraded and many
upgrades, changes and improvements were incorporated by the time your
engine was built.
Some customers have also installed pressure gauges on the outlet of the
lift pump and ahead of the injection pump, to verify positive pressure
to the VP-44; this is all well and good, but does present another
failure mode and additional fuel leak path opportunity, and we do not feel
that such monitoring gauges are necessary. Clean, contaiminant and
moisture-free fuels are necessary, and this should be your main concern.
Here is some more information on the VP-44: The VP44 is a
radial-piston pump with 3 pistons. The pistons are attached to the distributor
rotor and the fuel pump shaft. The pistons ride inside a cam ring (think of
a donut with a "bumpy" hole) so as the pump shaft rotates the piston
carrier, the pistons are compressed towards the center, pressurizing the
fuel. The pressurized fuel is then directed to the proper cylinder by
the distributor rotor.
The cam ring can be rotated in a "retarded" or "advanced" direction;
this is done using a solenoid valve, which modulates pressure to a
fuel-pressurized piston beneath the cam ring. Also, the start and end of
injection are controlled by a solenoid valve.
Although the VP44 was initially not as reliable as we would have liked,
Cummins and BOSCH are confident in its reliability today. The VP44 is
much less complicated internally than the P7100, and it has many fewer
finely machined parts. We don't know for sure that BOSCH considered
low-sulfur fuel when designing the pump, since the pump is fuel lubricated
and today's fuels are low-sulfur.
The VP44 is completely fuel lubricated, as the VE pump is. It does not
use oil lubrication like the P7100 does. The VP44 is expected to last
at least a long as the P7100 in normal automotive applications. However,
we obviously have much more "long-term" experience with the P7100 than
we do with the VP44, so our knowledge base is still evolving. Soon
after launch, the VP44 had its share of problems, just as the P7100 did
when it was introduced, but we have worked closely with BOSCH to correct
the issues with the pump, and we're confident that the VP44 will be a
reliable fuel pump.
Fuels with low lubricity can cause increased wear or seizure of the
VP44 fuel pump internal components. If you are not sure of the fuel you
use add a lubricity additive is required.
In March 2000, we contacted Bosch and they advised us that the
so-called "B-10" life of the VP44 is 2000 hours at full fuel rating. In other
words, If a pump were operated at 100 percent rated horsepower for 2000
hours, only 10 percent would fail; 90 percent would be okay. As the
typical duty cycle of the Dodge Ram is considerably less than this, the
expected life expectancy is considered more than adequate to meet the
needs of the Dodge Owner
The electronic controls on the 24-valve engine allow Cummins to control
the power and torque very precisely across the entire RPM range. The
mechanically controlled engines have their power and torque precisely
controlled at torque peak and rated power RPMs, but between those two
engine speeds, power and torque can often exceed the published figures.
Do be sure you use quality filters and fluids. We have found their
greater initial investment to be a good idea and to actually lower the
total cost of operation per mile, or hour. Cheap filters are a poor
investment.
Enjoy your truck and drive it anywhere you want to go. It should do you
a good job. Take the other actions as appropriate given you fuel
quality and sensitivity about "mission disabling failures. "
Thank you for choosing Cummins power or products. Please let us know if
you need assistance in locating the nearest Cummins-authorized
distributor or dealer. Please feel free to use our International Dealer
Locator: (http://www.cummins.com/partserv/intro.html) found on the Customer
Assistance page of the Cummins website (www.cummins.com).
Let us know if have other questions, or if away from your computer,
feel free to call us (toll-free, from North America) at 1-800-DIESELS
(343-7357), or 1-812-377-5000 (toll call, worldwide, ask for 800-DIESELS).
Regards,
--
Powermaster
Customer Assistance Center
Cummins, Inc.
Columbus, Indiana, USA
Email: -- email address removed --
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