my transfer pump went out and caused my injection pump to go out when i went to put in a new tranfer pump dodge recommented the new intake transfer pump so that is what i did and then when i took it to another shop to have the injection pump put in because it was alot cheaper than dealer he said that the new intank transfer pump didnt put out enough pressue he said it only puts out about 4 8 psi and that it was not enough pump so when i asked the dealer about this they said its not the pressure that is important it is the volume of the fuel that it puts out they said it has way more flow than the old style transfer pumps that where mounted on the block dose anyone know anything about these intank transfer pumps?

<edit by SH>

 

deltriolo: I had my 0216 code in the summer of 2005 at about 87k miles. At that time they replaced the VP44 and installed the intank fuel pump. the pressure was 8psi at idle, and would drop to 3 at mild acceleration and almost 0 at WOT.
Needless to say I wasn't very happy about that. I limped it home and ordered a Vulcan kit. I now read my fuel press at the port entering the VP44. and at idle I have 9psi and at WOT it reads 6psi. (So far so good) If I had it to do over, I would have gone for a Fass or another out of tank pump at that time. As I said "so far so good" I'm at 120k mi now and knock on wood its still doing it. But Im ready for the change over if needed.

 

what did it cost for you in have the intank transfer pump put in and did the dealer do it mine was close to $800.00

 

here is a truly stupid question. Given the realities of pressure vs. flow.

How would a pump that puts out less pressure than the previous pump, manage to flow more through the same sized lines as the previous pump was using?

Now, I am not trashing anyone on this board. I am merely pointing out a question that I asked a "technician" at our local dealership. His response was that the intake pump was created as a high volume, low pressure pump. Volume being more important than pressure, for cooling of the VP44. I whole-heartedly agreed that more volume is definitely the answer to keeping the VP cool, however, back to the original question.

When you have a 3/8" line, lets say you flow 15 GPM at 15psi. Now, take that same sized line, and decrease the pressure to 10psi. you are now flowing 9.9 gpm give or take, unless my math is out to lunch. Reduce it to 8 psi, and now you are flowing 7.9 gpm give or take. The only way to increase volume is to either increase pressure, or increase the size of the line. Since they are maintaining the line size, and decreasing the pressure, there is no logical ( thanks Spock ) way that it will be " higher volume ".
With either larger lines, or a no-restriction situation, the numbers become somewhat muddied, but either way, lower pressure does not equal more volume per given size of hose/tubing/pipe in this situation.

Now, this is just food for thought, hopefully I didn't screw it up so badly as to confuse people. Make your own call on the in-tank conversion. Just remember the added work and cost when its time to do it again.

Good luck, and may the force be with you.

 

I had my vp-44 replaced and had the intank pump installed in April of 2006. My gauge would read 6 psi at idle and 1 psi on the interstate. So I installed a Holley Blue pump. Now I get 25 psi at idle. It is awesome!!

 

so should i install another lift pump or incrase the hose diameter and if another pump is nessasary what kind and how much i dont think i have the money for a fass fuel system any more since i wasted it on the intank transfer pump

 

They will tell you that it does because there is less "friction loss" due to the lower pressure... JK

 

i hear that its not the restriction from the hose its the pump inself that is not able to alow more than a certain amount of fluid through it. the old style transfer pump will put out around 40 -50 oz. per minute with or with out the hose atached to it that is all the volume that can move through the pump itself i herd that the intank transfer pump has twice the flow as the old style plus it is not subject to heat and vibration from the moter and it sits in gas where it can stay cool and it dosnt have to suck the fuel it pump it instead so it is not hard on it at all. has anyone ever herd of these intank trasfer pumps going out i know the old kind dose all the time

 

The problem with the flow vs pressure analogies..

We arent measuring the flow of the lines at full pressure with no restrictions. That would mean the fuel is 100% consumed and no fuel returned to the tank.. Which is contradicted when stated about being cooled.

Higher pressure does not always mean more flow. It can also means more restriction.

You take a 10psi garden hose, you can put your finger over the end and get 25 psi out of it cant you?

Its completely possible the internals of the fuel pump are larger and less restrictive.

THINK outside the box.

 

i find it kind of hard to belive that dodge whould come up with this fix when all the engineers for dodge and cummins are trying to prevent more warrenty fixes and less brake downs dodge said they dont even make the old style tranfer pump any more. its kind of hard to find out the answer when you ask the dealer and they will say there pump is better and then you ask another shop who dosnt offer the part and he says the one of his pumps is better that and it is the same pump that they are putting in all new truck 2003 and up

 

"and it sits in gas where it can stay cool"

Oh I hope not.

 

The only stupid question is the one you don't ask.

This is probably going to be a long response, so bear with me.

It could be possible to have a pump provide more flow at a lower pressure. If you're only talking about one pump, this could be true for a centrifugal pump (vice displacement pump) and would be dependent on impeller and volute design. In the case of our fuel pumps, this isn't what we're talking about, so this reasoning is bogus,....most likely (I'll explain later).

What you say about decreased pressure=decreased flow would be true if we're talking about a pump pushing fluid through a length of pipe with a given friction factor, measured at a given point downstream of the pump. Where this gets complicated is that we're talking about 2 pumps and the pressure is measured between them. The first is constant displacement. It provides a certain amount of fuel to the injection pump regardless of how much is used. The second pump (injection pump) varies the amount of fuel it pumps based on the fueling demand.

When the fuel pressure is measured between the two pumps you will see a lower pressure at WOT than you will at idle. This is true of 1st and 2nd gen in particular.

Now I'm going to make it even more complicated. With a common rail system (3rd gen), the HP pump (injection pump) will create a given pressure in the rail (~3000psi or whatever) and the fuel not used will be returned to the LP side of that pump (or some other low pressure area in the system). In this system it is possible that the lift pump maintains a certain pressure to the intake of the HP (injection) pump which could explain a high flow/low pressure situation IF the unused fuel is returned to somewhere other than the suction side of the HP pump (same as discharge side of the LP pump).

However comma. I see that we're talking about a '00 and '01. Low pressure means your injection pump is working harder, and therefore more likely to fail. Remember, the pressure here is measured between the two pumps.

THE BOTTOM LINE: For the 2nd gen trucks (I'm not 100% sure about 1st or 3rd gen) you should have 15 psi at idle and not drop below 10 at WOT.

-SFB

I hope this makes some sort of sense.

 

Ok, I have said this a zillion times before, but after reading this thread I feel compelled to say it again.

In the case of the intank pumps and their lower pressure but claimed higher "volume"....

We all know that pressure is simply the resistance to flow, right? In this particular fuel system the restrictions that cause pressure are the VP44, fuel filter and lines. Changing the lift pump and relocating it to the tank, the existing restrictions in the system (the VP, filter and lines) remain constant (they did NOT change) regardless of where the pump was placed. The ONLY way to reduce the pressure if the restrictions have not changed is to reduce the flow.....meaning, the intank pump flows considerably less.

Clear as mud?

So, anyone that tells you that the intank pump is flowing more at a reduced pressure when the existing restrictions have remained constant needs to take physics class again - yes, the DC techs too if that is the rubbish they are spewing to their customers! This is not my opinion but an inarguable fact of physics. Again, the pump is flowing LESS if the pressure has dropped but the restrictions have remained constant!!!!! A pump does not produce pressure, it produces flow....pressure is only the resistance to flow.

The intank pump is a step backwards and is a bit of a blunder by DC - especially when they attempt to contradict physics in their explanation of why it performs poorly and certainly worse than the block mounted LP.

I feel better now!

 

The one fact you are not taking into consideration is that a pump is more efficient pushing than sucking. When the pump is move from the engine to the tank the long suction line is eliminated. I do agree it is impossible to increase the flow through the same lines while reducing the pressure. If Dodge has found a way they should patent it and sell it to every major city for their water systems.

 

True. But, it is all dependent on where the pressure is being measured. Moving the pump to the tank (like 90% of the EFI gasser currently do) is far easier on the pump. But since most are measuring FP at the end of the (lower pressure portion of the) line, lower pressure at that point would be indicative of lower flow.