piperca

I read this over on TDR:

http://www.turbodieselregister.com/f...d.php?t=149837

Anyone got any info. on this, the thread does not elaborate?

AggieJustin

That sounds like way too much new functionality for just being a new lift pump part number. In order to pull off all that stuff, you'd need new ECM programming, fuel pressure sensors, etc. I'll keep an eye on it to see what the source is, but it doesn't sound too realistic.

CTD NUT

I have heard about this before......there is a small ECM reflash involved to trigger the light along with a wiring harness. To my knowledge, this has nothing to do wtih a LP "kit" and it is not offered from DC - just Cummins.

2500WHITERAM

gentlemen..
the new lift pump kit is same design as 06 trucks. Its a fuel pump module conversion kit and replaced the old lift pump assy.
pn# 5175538aa is the entire complete kit with harness and pump
pn# 5179873aa is a replacemnt module for trucks in which this conversion was already done. The idea that its easier to push fuel, than draw it up applies. its quite a solid and neat install..took me 2 hours to drop tank and install. full kit was 380.00 list.

if any of you all are interested, i can get you the kit at a good price...
pm me if interested

supr

So, would this be a better solution that an FASS?

AggieJustin

Some people haven't been overly impressed with the in-tank pump due to the low pressures they're seeing at WOT. I know the new DC stance is that volume is more important than pressure, but most people like seeing the higher and more stable pressures provided by FASS or other pumps than going with the in-tank pump. Not to mention that if/when the in-tank pump fails, you've got to drop the tank for replacement.

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.

AggieJustin

No trouble CTD NUT...I've never really understood how they justify the position that you can flow more fuel at a lower pressure when you don't change anything else. I know DC took the flow vs pressure position back before they even came out with the in-tank pump when they were trying to dodge some of the warranty replacements of the Carter pump.

I'd just much rather see my pressure hold steady at 15-16 than watch the needle bury itself on zero when I make a WOT run. After all, how can you have flow if you have no pressure?? Only if the VP44 is pulling the fuel itself...

Needless to say, when my LP finally goes TU, no in-tank pump for me.

Barry St John

Well put which is why one of the first things to improve pressure at the injection pump is to open up restrictions in the fuel delivery system such as quick disconnects, small lines and those lousy banjos!

amartinson

Nice Post!

I have felt the same way every time this subject gets brought up.

J BODY

Interesting comments.... I still have a stock system on my 01. I'm in doubt with all these "big line kit", "banjo eliminators", "larger pumps"......but people still utilize the stock fuel module in the tank. You can go as big as you want up front....but most are still moving fuel through that tiny ID nipple on the stock module.

AggieJustin

I think most of it comes down to tackling the easiest stuff first. Larger banjos are an easy swap. Doing the full big line kit from the LP to the IP isnt much harder. Even dropping a new pump into the existing setup is pretty quick. All of these things will give you improvements in fuel delivery, even without upgrading the stock fuel pickup in the tank.

I'm still running the stock LP on mine, but I've got a big line kit up front with no banjos. I saw an increase in idle pressures, and much more stable WOT pressures. So I'd say it's definitely worth it. Would I see an even bigger benefit from upgrading the pickup? Yeah, of course, because I'd remove the restrictions from the fuel supply to the LP. But I haven't had time (or a place) to drop my tank and do that work. And at my present HP level, I'm still able to supply enough fuel, so that project is on the back burner for a little while.

crobtex

T7 or other firefighters please chime in if I'm wrong.

If I remember my hydraulics correctly, the larger the hose/nozzle the higher the flow......the smaller the hose/nozzle the higher the pressure. If this is correct, it only makes sense that larger fuel lines (higher flow) coupled with higher constant pressure for the added fuel would be the ideal situation.

Barry St John

True but if that tiny nipple is enough to feed the pump with out cavatating it's on the suction side and won't have any overall effect on pressure at the injection pump. IMO you start with the output pressure at the lift pump and each restriction reduces that pressure by the amount of that restriction at a given volume. If you have enough hp that your demand is high enough to starve the lift pump at the source side then you will see reduced pressure also but you will be able to see it at the output side of the lift pump. Maybe this is a problem and if so could be a major factor in the high failure rate of the lift pumps. They do seem to work better mounted back at the tank which eliminates the restriction at the quick disconnect. It sure wouldn't hurt to open up the feed at the tank as well. Some people have done this with good results it just depends how far you want to take it!

AggieJustin

It is surprising how much restriction that adds to the supply side. When I installed my big line kit, I did the supply side of the LP a couple of days before I did the lines between the LP and IP. But just replacing the line into the LP gave a nice boost in pressure on my FP gauge.