New lift pump kit from Cummins???
02-01-2006, 08:03 AM
#16
Chapter President
I installed the FASS II and larger lines to the filter before I added the larger line from the filter to the IP. When I added the larger line to the IP, my pressure dropped by about 1.5 psi. To me, this make sense....larger line=more flow and less pressure.
02-01-2006, 08:17 AM
#17
...but as example. I have a truck in the bay right now with a dead VP. Customer has a fp gauge and is cussing the stock lift pump that was installed two years ago, but only 39,000 miles. All this discussion, and a rather slow day let me play a bit. Being it's a 99 I removed the line from the top of the canister that runs to the VP and installed my test fitting with a clear hose on it. Bumped the starter and let the fuel flow to make sure the canister was full and the line purged of air. I then bumped the starter again and let the fuel flow into a jug. Measured and repeated. Came out to 1475 liters twice. This was with a supposed "bad" pump with only 3psi at idle (verified this with my gauge also). Installed the customer supplied in tank kit (Dodge one). After the install the truck had 8 psi at idle (which is about the norm for that kit from what i've seen). Performed the volume test the same as above. It netted 1350 liters twice.
02-01-2006, 08:24 AM
#18
Chapter President
One thing to remember when installing larger fuel lines and eliminating the banjo bolts is that most pressure readings are taken AFTER at least 2 of the banjo bolts in the fuel system depending on the model year and where you are measuring pressure. Banjo bolts are a huge restriction AND cause turbulent flow, which, in turn causes another resistance to flow BEFORE the first banjo bolt on the pressure side of the pump. Installing a kit like a Scotty Smartfuel eliminates the banjos and replaces them with smooth radiused fittings that certainly allow for a noticable laminar flow.
My point is, that the high fuel pressure was always present within the system - BUT, it was upstream of where the system pressure is typically measured. Removing the banjos eliminates the turbulence, promotes laminar flow AND moves the point of the highest restriction within the fuel system AFTER where it is typically measured. This is why after the installation of a Scotty Smartfuel you don't have a large change in idle FP but you do see a sizable pressure increase at WOT when the demand for fuel is at it's highest point.
My point is, that the high fuel pressure was always present within the system - BUT, it was upstream of where the system pressure is typically measured. Removing the banjos eliminates the turbulence, promotes laminar flow AND moves the point of the highest restriction within the fuel system AFTER where it is typically measured. This is why after the installation of a Scotty Smartfuel you don't have a large change in idle FP but you do see a sizable pressure increase at WOT when the demand for fuel is at it's highest point.
02-01-2006, 08:37 AM
#19
Chapter President
Originally Posted by J BODY
...but as example. I have a truck in the bay right now with a dead VP. Customer has a fp gauge and is cussing the stock lift pump that was installed two years ago, but only 39,000 miles. All this discussion, and a rather slow day let me play a bit. Being it's a 99 I removed the line from the top of the canister that runs to the VP and installed my test fitting with a clear hose on it. Bumped the starter and let the fuel flow to make sure the canister was full and the line purged of air. I then bumped the starter again and let the fuel flow into a jug. Measured and repeated. Came out to 1475 liters twice. This was with a supposed "bad" pump with only 3psi at idle (verified this with my gauge also). Installed the customer supplied in tank kit (Dodge one). After the install the truck had 8 psi at idle (which is about the norm for that kit from what i've seen). Performed the volume test the same as above. It netted 1350 liters twice.
We must remember that there is only ONE reason why the system pressure fell in the first place: Because the worn out LP failed to flow enough fuel to to get up to the appropriate operating pressure.
Measuring FP still stands as an acceptable way to gauge LP performance.
02-01-2006, 09:23 AM
#20
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Originally Posted by CTD NUT
I already know that I am going to be saying this until I am blue in the face.......BUT.....many people here need to better understand the relationship and the difference between pressure and flow (including some mechanics that are giving some of the "advice"). Pressure is only the resistance to flow......period. Pumps can NOT produce pressure - they can only produce flow. The pressure rating of a pump refers the amount of resistance to flow that it can overcome to deliver it's flow rating at the specified pressure.
That said, if we assume the the resistance to flow in the system (in this case, the LP's resistance to flow is the VP44) remains constant (i.e. it doesn't change), the ONLY way to increase the pressure to the VP, is to increase the flow. It also works the other way, too. Again, if we can assume the resistance to flow stays constant within the system (we are not changing anything in the VP that will somehow alter it's flow capability when we change lift pumps), the ONLY way to reduce pressure, is to reduce flow.
The bottom line: If nothing is changed other than the LP and there is a system pressure drop, the only way that can occur is because there has been a drop in flow (volume).
If someone tries to feed you some hog wash that the intake pump flows more fuel and does so at a lower pressure within the existing fuel system, they are not fully aware of what they are talking about and are incorrect.
AggieJustin,
This was not directed at you.....some of these dealers that are feeding this BS need a physics lesson and they are consequently confusing and misleading some people.
Sorry for the rant, but I am tired of hearing that a LP can flow more fuel at a lower pressure within the existing fuel system when the restriction remains unchanged - it simply is not possible.
That said, if we assume the the resistance to flow in the system (in this case, the LP's resistance to flow is the VP44) remains constant (i.e. it doesn't change), the ONLY way to increase the pressure to the VP, is to increase the flow. It also works the other way, too. Again, if we can assume the resistance to flow stays constant within the system (we are not changing anything in the VP that will somehow alter it's flow capability when we change lift pumps), the ONLY way to reduce pressure, is to reduce flow.
The bottom line: If nothing is changed other than the LP and there is a system pressure drop, the only way that can occur is because there has been a drop in flow (volume).
If someone tries to feed you some hog wash that the intake pump flows more fuel and does so at a lower pressure within the existing fuel system, they are not fully aware of what they are talking about and are incorrect.
AggieJustin,
This was not directed at you.....some of these dealers that are feeding this BS need a physics lesson and they are consequently confusing and misleading some people.
Sorry for the rant, but I am tired of hearing that a LP can flow more fuel at a lower pressure within the existing fuel system when the restriction remains unchanged - it simply is not possible.
Most guys out there are dying to get this done...4 of my techs did their trucks right away, even thought their pumps were in good operating condition
02-01-2006, 10:10 AM
#21
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So, lets' cut to the chase; Is best pratices in most CTD Gen 2 opions: A Vulcan relo/bigline/Fass 2?
Seems everyone agrees on Fass 2, biggerlier lines & relo sem to be debatable.
After the physics, is that where we are?
500,000 or more Gen 2 owners want to know!!!
Seems everyone agrees on Fass 2, biggerlier lines & relo sem to be debatable.
After the physics, is that where we are?
500,000 or more Gen 2 owners want to know!!!
02-01-2006, 11:19 AM
#22
Chapter President
Regardless of the LP used, ditching the banjos is most certainly beneficial for the reasons I mentioned earlier. Only those that don't have first hand experience with the higher flowing fittings are the skeptics. I am not a fan of the FASS pumps or over pressurizing the VP as I have yet to see ANY benefit. The factory LP appears to be quite durable when not bolted to the side of the engine. If performance and durability are a priority, any fuel pump that has it's motor cooled and lubricated by fuel instead running unlubricated and cooled by ambient air, will have superior durability and longevity and the FASS pumps have niether characteristic.
I use the Scotty Smartfuel kit with the stock LP and have excellent fuel system performance reliability for my fueling level.
I use the Scotty Smartfuel kit with the stock LP and have excellent fuel system performance reliability for my fueling level.
02-01-2006, 05:18 PM
#23
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I do not think there is enough experience by the Gen 2 people with the Bosch pump relocated. If there are a lot of folks out there that have done this for over a year or 2, let's hear about it.
Most people view the stock lift pump, with it's wonderful 6 MONTH WARRANTY, to be suspect or worse. The only thing that fails more is Democrats running for President. (One good one, maybe, every 25 years?)
Most people here seem quite happy with the FASS & 4 YEAR WARRANTY.
I think even Cummins sell this as a cure.
Gen 2er's just want something reliabe, proven, and will pay for this, more so than BOMS(Maybe?). Without fuel, BOMS don't work!!
My $ .02!
Most people view the stock lift pump, with it's wonderful 6 MONTH WARRANTY, to be suspect or worse. The only thing that fails more is Democrats running for President. (One good one, maybe, every 25 years?)
Most people here seem quite happy with the FASS & 4 YEAR WARRANTY.
I think even Cummins sell this as a cure.
Gen 2er's just want something reliabe, proven, and will pay for this, more so than BOMS(Maybe?). Without fuel, BOMS don't work!!
My $ .02!
02-01-2006, 08:49 PM
#24
Administrator
All I know is that I went through four lift pumps in 140000 miles, the last of which I changed out alongside the road two years ago the day before Thanksgiving in Lynchburg, Virginia. A gentle breeze rolling down out of the north about a thousand miles an hour and cars and trucks whipping by stirring that up even more. I was lucky to get ten pounds out of the stock pumps. Had Keith put the FASS on and pressure stays at 14 to 15 with over 390 hp. No more stock crap for me. Not telling anyone what to do here, just relaying facts. The FASS has lasted longer already than any of the stock pumps.
02-04-2006, 02:58 PM
#25
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lift pump
i have a 2000 dodge 2500 4x4 quad cab 119,00 miles. i have read a lot of the threads and it sounds like i need a lift pump.i just replaced the crank case position sensor and it did not help the problem. where is the best place to get a lift pump and what kind? i do not have a fuel pressure gauge so i do not know what the psi is. thanks to all.
02-05-2006, 08:24 PM
#26
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Originally Posted by supr
So, would this be a better solution that an FASS?
02-06-2006, 09:03 AM
#27
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gfd121-
www.genosgarage.com is a good place for gauges & some parts.
If under warranty, go see your dealer or Cummins, they can check it.
If not under warranty, I would go to Cummins. Several sources here have other sources if you search.
I think most agree that a relo kit & FASS are the preffeed long term solution.
As some have said, having a back up pump is not a bad idea.
Good luck!
www.genosgarage.com is a good place for gauges & some parts.
If under warranty, go see your dealer or Cummins, they can check it.
If not under warranty, I would go to Cummins. Several sources here have other sources if you search.
I think most agree that a relo kit & FASS are the preffeed long term solution.
As some have said, having a back up pump is not a bad idea.
Good luck!
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