So I can hurt my CP3 if........?
09-29-2006, 03:23 AM
#1
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So I can hurt my CP3 if........?
My fuel lift pump goes bad? I am at 82k and I have something humming and rattleing under my hood, which I think is the fuel pump, early 04 model. If this goes out, will I hurt my truck?
09-29-2006, 04:18 AM
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If your stock LP goes bad then your truck will stop running. This way it will not harm the CP3 like it did in the earlier years with the VP44. Your CP3 will be fine but you will be broke down somewhere......
09-29-2006, 06:51 AM
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Everything I have read is that it will not pull through a bad LP. That's one of the reasons I liked my FASS. The CP3 could pull fuel through it if it stopped running. These CP3s run just fine without a LP. It's my understanding that these trucks would do fine, in stock form, without any LP at all!! Am I wrong??
09-29-2006, 07:21 AM
#7
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Our fuel lines are too small for the CP3 in drawing fuel via suction. With larger lines it can. That's how the LB7 and LLY Duramax's did it.
So without a lift pump our trucks will just sputter and die.
MikeyB
So without a lift pump our trucks will just sputter and die.
MikeyB
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09-29-2006, 08:04 AM
#8
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My wife's 2005 Jeep Liberty Limited 4x4 CRD (2.8L CRD w/CP3) has no lift pump......just makes the fuel filter changes a little more time consuming.
I, too, was under the same understanding as Dodgezilla.
Knock on wood, at 43k miles, no lift pump problems on my '03 and I always have around 8>>>9 psi on average.
I sometimes wondered about performing a CRD fuel filter/housing "conversion" on my '03 to eliminate the LP DOA on-the-road syndrome. As stated earlier, the DuraMax (and CRD's) do just fine without a lift pump.
Greg
I, too, was under the same understanding as Dodgezilla.
Knock on wood, at 43k miles, no lift pump problems on my '03 and I always have around 8>>>9 psi on average.
I sometimes wondered about performing a CRD fuel filter/housing "conversion" on my '03 to eliminate the LP DOA on-the-road syndrome. As stated earlier, the DuraMax (and CRD's) do just fine without a lift pump.
Greg
09-29-2006, 08:43 PM
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09-29-2006, 10:34 PM
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How do you figure that the CP3 has starved itself and caused damage.
This is an assumption, not a fact.
The CP3 is a very good pump. Unlike the VP that the second that it had a hint of low fuel pressure and flow it broke. Normally the CP3 will detect low pressure and shut itself off. As long as you have the min required flow, the CP3 will keep running.
When the rail pressure drops to low which is what would happen in a fuel starved situtation then the CP3 will shut off by the ECM via the FCA.
Now you have to have hit precondtions such as vehicle speed, fuel flow and rail presure. Before the CP3 will turn off.
Really if it pulls through the dead LP then more then likely the CP3 is fine as their was enough fuel in the system to keep the pressure in check.
If you engine went into limp mode and you kept pushing it that would be a different story.
This is an assumption, not a fact.
The CP3 is a very good pump. Unlike the VP that the second that it had a hint of low fuel pressure and flow it broke. Normally the CP3 will detect low pressure and shut itself off. As long as you have the min required flow, the CP3 will keep running.
When the rail pressure drops to low which is what would happen in a fuel starved situtation then the CP3 will shut off by the ECM via the FCA.
Now you have to have hit precondtions such as vehicle speed, fuel flow and rail presure. Before the CP3 will turn off.
Really if it pulls through the dead LP then more then likely the CP3 is fine as their was enough fuel in the system to keep the pressure in check.
If you engine went into limp mode and you kept pushing it that would be a different story.
09-29-2006, 11:09 PM
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How do you figure that the CP3 has starved itself and caused damage.
This is an assumption, not a fact.
The CP3 is a very good pump. Unlike the VP that the second that it had a hint of low fuel pressure and flow it broke. Normally the CP3 will detect low pressure and shut itself off. As long as you have the min required flow, the CP3 will keep running.
When the rail pressure drops to low which is what would happen in a fuel starved situtation then the CP3 will shut off by the ECM via the FCA.
Now you have to have hit precondtions such as vehicle speed, fuel flow and rail presure. Before the CP3 will turn off.
Really if it pulls through the dead LP then more then likely the CP3 is fine as their was enough fuel in the system to keep the pressure in check.
If you engine went into limp mode and you kept pushing it that would be a different story.
This is an assumption, not a fact.
The CP3 is a very good pump. Unlike the VP that the second that it had a hint of low fuel pressure and flow it broke. Normally the CP3 will detect low pressure and shut itself off. As long as you have the min required flow, the CP3 will keep running.
When the rail pressure drops to low which is what would happen in a fuel starved situtation then the CP3 will shut off by the ECM via the FCA.
Now you have to have hit precondtions such as vehicle speed, fuel flow and rail presure. Before the CP3 will turn off.
Really if it pulls through the dead LP then more then likely the CP3 is fine as their was enough fuel in the system to keep the pressure in check.
If you engine went into limp mode and you kept pushing it that would be a different story.
09-29-2006, 11:43 PM
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First of all , the CP3 cannot be shut down by FCA, why? because it is a normally open valve..... for safety reasons. with a lift pump failure , some engine will run and some will not run.
reason the chevy's dont use a lift pump is they use the low pressure pump on the CP2 to draw the fuel in and then thru the filter and then on to the high pressure side of the CP3.
you will notice the 07 6.7Liter, they eliminated the lift pump and did the same thing by drawing fuel with the low pressure pump on the CP3 and then going to the filter and back to the CP3 high pressure side of the pump. about time too.
If you unplug your lift pump , it may be able to run, but dont try to tow anything or put it under a load , you will have to much restriction to the CP3
reason the chevy's dont use a lift pump is they use the low pressure pump on the CP2 to draw the fuel in and then thru the filter and then on to the high pressure side of the CP3.
you will notice the 07 6.7Liter, they eliminated the lift pump and did the same thing by drawing fuel with the low pressure pump on the CP3 and then going to the filter and back to the CP3 high pressure side of the pump. about time too.
If you unplug your lift pump , it may be able to run, but dont try to tow anything or put it under a load , you will have to much restriction to the CP3