Aftermarket fuel pumps
#31
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HOHN you're a smart fellow and I agree with most of what you said. I especially like the part about the larger injectors. That certainly is one of the variables in VP reliability since reducing the VP's work load reduces heat.
I plan on larger injectors soon but making sure I can pay for an upgraded clutch at the same time is necessary. I'm not sure I'd want Mach 2's though. Maybe to big? I thought possibly 275's or Mach 1.
As for the OEM lift pump, after being a believer that the OEM lift pump "could" work, I found that the most common reason the lift pump fails is because of restrictive fuel lines. Not because it "pulls" instead of pushes fuel. The lift pump is regulated at 15 psi but with so little volume running through the fuel lines the regulator check ball eventually beats itself into the lift pump housing whereby over time the pressure over regulates and the pressure drops. So increasing the fuel line diameter or even simply getting rid of the banjo fittings helps greatly. But even with that, the OEM lift pump is built too inexpensively and has other poor quality issues, like using "glue" to hold the impeller to the pump shaft with plastic which eventually comes loose. Also, on my truck I found a section of fuel line between the VP and fuel filter that measured 1/8" ID. Unbelievably small but the only reason anyone could think of for this would be Cummins attempting to reduce VP dynamic fluid pulses from reaching the lift pump. Who knows but it was also clear that not all trucks had this 1/8" section.
I plan on larger injectors soon but making sure I can pay for an upgraded clutch at the same time is necessary. I'm not sure I'd want Mach 2's though. Maybe to big? I thought possibly 275's or Mach 1.
As for the OEM lift pump, after being a believer that the OEM lift pump "could" work, I found that the most common reason the lift pump fails is because of restrictive fuel lines. Not because it "pulls" instead of pushes fuel. The lift pump is regulated at 15 psi but with so little volume running through the fuel lines the regulator check ball eventually beats itself into the lift pump housing whereby over time the pressure over regulates and the pressure drops. So increasing the fuel line diameter or even simply getting rid of the banjo fittings helps greatly. But even with that, the OEM lift pump is built too inexpensively and has other poor quality issues, like using "glue" to hold the impeller to the pump shaft with plastic which eventually comes loose. Also, on my truck I found a section of fuel line between the VP and fuel filter that measured 1/8" ID. Unbelievably small but the only reason anyone could think of for this would be Cummins attempting to reduce VP dynamic fluid pulses from reaching the lift pump. Who knows but it was also clear that not all trucks had this 1/8" section.
My pump has lasted, so it would be tempting to say that this has something to do with it.
But logically, the larger lines cannot increase lift pump life based on flow or pressure changes.
The VP44 inlet acts like a variable orifice. Under almost all conditions, the VP is the greatest restriction in the system (only when are approaching zero fuel pressure at the VP inlet is it not).
All a bigger line kit does in term of restriction is shift the balance of the VP's restriction and the line's restriction. The total restriction the LP sees is the same, it's just split differently between VP and supply plumbing. Let's say you had stock banjos and read 9psig at the VP inlet, then swap in a big line kit and read 14psi at the VP. That means there is still 14psi of restriction to flow, and (if measured under the same conditions), you can infer that the factory banjos were 5psi more restrictive.
But you will not measure any more flow through the system.
When you step on it and the pump goes WOT, it becomes a much larger effective orifice that is far less restrictive. Thus, the pressure you will read will go down even as flow is increasing. The increase in flow makes the lines proportionally more restrictive (Just as voltage drop is a function of current and resistance, so is pressure drop a function of flow and restriction). But the VP is STILL proportionally more restrictive than the plumbing is.
As long as you measure positive pressure at the VP, the VP is more restrictive than your plumbing is.
Since the restriction that the LP sees doesn't change with a larger line, it cannot affect the internal regulating ball inside the LP. You'll still have the same amount of internal recirculation of the LP (or not, depending on flow demand).
There is one way I can see that a larger line might help with LP regulator life, and that is by damping more of the pulses from the VP that tend to hammer on that little ball and spring. If it stores fuel volume (like an accumulator) it damps these pulses like a resonator in an exhaust system similarly damps pulses.
Since I have a fluid-filled mechanical guage reading right off the VP, I can tell you that the pulsing at the VP inlet is considerable.
Justin
#32
Registered User
Wildcat Diesel..... What happened to them?
I understand what you're saying but I think you're forgetting to consider the overflow valve and how important the role that little component plays. Even though the overflow check ball valve is spring set at 14-16 psi for maximum flow, the fuel system always remains a constant flow of fuel with only the fuel pumps capacity determining how much volume passes. Without changing the subject, the OEM lift pump simply cant pump enough volume and pressure to overcome the overflow valve in addition to the overly restrictive fuel lines, so even though the fuel system is always flowing, its just not enough fuel to properly cool the VP along with supply the engine. If the VP was the only varying factor in how much fuel flows through the system then it would certainly cook itself in no time.
Good conversation too.
I understand what you're saying but I think you're forgetting to consider the overflow valve and how important the role that little component plays. Even though the overflow check ball valve is spring set at 14-16 psi for maximum flow, the fuel system always remains a constant flow of fuel with only the fuel pumps capacity determining how much volume passes. Without changing the subject, the OEM lift pump simply cant pump enough volume and pressure to overcome the overflow valve in addition to the overly restrictive fuel lines, so even though the fuel system is always flowing, its just not enough fuel to properly cool the VP along with supply the engine. If the VP was the only varying factor in how much fuel flows through the system then it would certainly cook itself in no time.
Good conversation too.
#33
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I am curious to know why, in 14 years, nobody has been able to come up with a way to relocate the computer for the pump. Chevy realized the problem on the 6.5 and relocated the board in less than two years. With millions of these trucks out there I just wonder............................................ ................
When did they stop using the VP44?
Rick
When did they stop using the VP44?
Rick
#34
Registered User
I am curious to know why, in 14 years, nobody has been able to come up with a way to relocate the computer for the pump. Chevy realized the problem on the 6.5 and relocated the board in less than two years. With millions of these trucks out there I just wonder............................................ ................
When did they stop using the VP44?
Rick
When did they stop using the VP44?
Rick
#35
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Wildcat Diesel..... What happened to them?
I understand what you're saying but I think you're forgetting to consider the overflow valve and how important the role that little component plays. Even though the overflow check ball valve is spring set at 14-16 psi for maximum flow, the fuel system always remains a constant flow of fuel with only the fuel pumps capacity determining how much volume passes. Without changing the subject, the OEM lift pump simply cant pump enough volume and pressure to overcome the overflow valve in addition to the overly restrictive fuel lines, so even though the fuel system is always flowing, its just not enough fuel to properly cool the VP along with supply the engine. If the VP was the only varying factor in how much fuel flows through the system then it would certainly cook itself in no time.
Good conversation too.
I understand what you're saying but I think you're forgetting to consider the overflow valve and how important the role that little component plays. Even though the overflow check ball valve is spring set at 14-16 psi for maximum flow, the fuel system always remains a constant flow of fuel with only the fuel pumps capacity determining how much volume passes. Without changing the subject, the OEM lift pump simply cant pump enough volume and pressure to overcome the overflow valve in addition to the overly restrictive fuel lines, so even though the fuel system is always flowing, its just not enough fuel to properly cool the VP along with supply the engine. If the VP was the only varying factor in how much fuel flows through the system then it would certainly cook itself in no time.
Good conversation too.
#36
I would think that moving the electronic from the heat, would be possible..
not easy..
sure its electrically noisy..so..what's the CPU freq? 200-500MHZ??
so..
if you own a cell phone the CPU most likely run faster(not the transmitter to the tower), the part the runs the apps..as in a smart phone..think 3-4X the 200-500MHZ number..my Xoom tablet is 1GHZ dual core,,fyi,,and not a phone..many android phones are this or more..
noise..or poorly made electronics? or EPA and banning LEAD?
its crazy to think that electronics cannot be made to survive long term at 200F..
sorry just crazy..
guys the ECM of out truck is mount to the engine block..don't you think this is over 200F most of the time..do we have lots of trouble with the ECM??no its the computer on the VP44..why? heat..the ECM should as hot as the VP44.. it doesn't get cooling..by fuel or air..but it lives..so..
WHY DOES THE VP44 die from heat?
so why move the electronics? they can stand the heat? doesn't the block get hotter than the fuel? thats cooling the VP44?
-dkenny
not easy..
sure its electrically noisy..so..what's the CPU freq? 200-500MHZ??
so..
if you own a cell phone the CPU most likely run faster(not the transmitter to the tower), the part the runs the apps..as in a smart phone..think 3-4X the 200-500MHZ number..my Xoom tablet is 1GHZ dual core,,fyi,,and not a phone..many android phones are this or more..
noise..or poorly made electronics? or EPA and banning LEAD?
its crazy to think that electronics cannot be made to survive long term at 200F..
sorry just crazy..
guys the ECM of out truck is mount to the engine block..don't you think this is over 200F most of the time..do we have lots of trouble with the ECM??no its the computer on the VP44..why? heat..the ECM should as hot as the VP44.. it doesn't get cooling..by fuel or air..but it lives..so..
WHY DOES THE VP44 die from heat?
so why move the electronics? they can stand the heat? doesn't the block get hotter than the fuel? thats cooling the VP44?
-dkenny
#37
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The block will not get much hotter than 200-229 degrees because it is water cooled. The VP is only cooled by the fuel running through it. When I hook up my scanner I see fuel temps around 140 degrees on a 60 degree day and at idle. I need to get the wife to drive so I can watch the other parameters closely. Problem is that with wife driving I am afraid to look down!
I will get my laser thermometer and see if the CPU is close to that temp indicated. I do not know where that fuel temp is being taken.
Rick
I will get my laser thermometer and see if the CPU is close to that temp indicated. I do not know where that fuel temp is being taken.
Rick
#39
Registered User
I would think that moving the electronic from the heat, would be possible..
not easy..
sure its electrically noisy..so..what's the CPU freq? 200-500MHZ??
so..
if you own a cell phone the CPU most likely run faster(not the transmitter to the tower), the part the runs the apps..as in a smart phone..think 3-4X the 200-500MHZ number..my Xoom tablet is 1GHZ dual core,,fyi,,and not a phone..many android phones are this or more..
noise..or poorly made electronics? or EPA and banning LEAD?
its crazy to think that electronics cannot be made to survive long term at 200F..
sorry just crazy..
guys the ECM of out truck is mount to the engine block..don't you think this is over 200F most of the time..do we have lots of trouble with the ECM??no its the computer on the VP44..why? heat..the ECM should as hot as the VP44.. it doesn't get cooling..by fuel or air..but it lives..so..
WHY DOES THE VP44 die from heat?
so why move the electronics? they can stand the heat? doesn't the block get hotter than the fuel? thats cooling the VP44?
-dkenny
not easy..
sure its electrically noisy..so..what's the CPU freq? 200-500MHZ??
so..
if you own a cell phone the CPU most likely run faster(not the transmitter to the tower), the part the runs the apps..as in a smart phone..think 3-4X the 200-500MHZ number..my Xoom tablet is 1GHZ dual core,,fyi,,and not a phone..many android phones are this or more..
noise..or poorly made electronics? or EPA and banning LEAD?
its crazy to think that electronics cannot be made to survive long term at 200F..
sorry just crazy..
guys the ECM of out truck is mount to the engine block..don't you think this is over 200F most of the time..do we have lots of trouble with the ECM??no its the computer on the VP44..why? heat..the ECM should as hot as the VP44.. it doesn't get cooling..by fuel or air..but it lives..so..
WHY DOES THE VP44 die from heat?
so why move the electronics? they can stand the heat? doesn't the block get hotter than the fuel? thats cooling the VP44?
-dkenny
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