Thank you guys I was able to purchase 2 pumps from http://www.hoeslidiesel.com/specials.htm for $139 each. Can't belvie my local dealer wanted $389 for one pump.
Bob
Bob
Bob4x4 said:you guys keep talking theory,I have seen most of these scenarios on a regular basis. Electric pumps will fail,period. If a stock pump on an 03 fails the pusher may not be able to push enough fuel through it to run. The same with a 2nd gen if the pusher fails the stock pump will not get you down the road with any certainty. If the in tank pump fails the pusher will not be able to pull enough fuel through it to run properly,in some cases it will be a tow-in. The only question is when, not if. Even the Rasp has issues... ... ... . do not put too much tension on the belt. The Fass has its own issues as well. There is no perfect set-up. Some work longer or better than others. I love fixing the trucks that belong to the engineers,they have all the theories but gee they still come in on the hook :-laf :-laf :-laf
Bob
JFaries said:This is because, it is hard to measure the volume required by the VP. So VP suction pressure has to be used. As long as there is pressure right at the VP suction there should be a capability of surplus fuel delivery provided by the LP. Nothing else really matters, pipe size nor LP design.
The VP is a variable speed positive displacement pump and it will pull what fuel it needs. If it can't, then it will eventually eat itself. Bad is bad, not to mention it is lubricated by fuel. Big surprise here.![]()
Jim
The VP is a variable speed positive displacement pump and it will pull what fuel it needs
I guess theoretically, if a gauge is reading 0psi (and not vacuum) then the LP is supplying enough fuel to the VP
cerberusiam said:HTML:The VP is a variable speed positive displacement pump and it will pull what fuel it needs
In the Ram truck configuration it is highly unlikely it will pull enough fuel for anything off idle. In a backhoe or other use where the fuel tank is mounted higher than the pump, different filters, line size, static rpm, etc, it may be able to but there is no indication Bosch ever intended it to do so, and, if it had to it would probably severely reduce its life expectancy. It is highly doubtful either Bosch, Cummins, or DC intentionally engineered but it definitely suffers from the differences between design and practical application.
HTML:I guess theoretically, if a gauge is reading 0psi (and not vacuum) then the LP is supplying enough fuel to the VP
That should read "if a gauge is reading 0psi (and not vacuum) then the VP is using all the fuel the LP is supplying". If the VP wasn't using all the fuel then there would be pressure building up. Whether or not it is enough is where the debate begins. Given the volume is enough 0 psi would be acceptable, just not in the configuration that is found in these trucks. Without the 10+ psi there is not enough flow to provide the VP with fuel for injection and lube/cooling functiuons due to the line size, restrictions, tank location, etc. The injection event is primary and the circulation is second. When supply volume equals required volume, 0 psi, fuel is pulled from circulation to supply the injection.
The pressures required to keep the VP happy, while not being very scientific but developed in actual application, are a minimum of 8 psi at WOT and 16 psi at an idle. The VP will live outside those paramters, and probably for a while, but these pressures seem to produce enough fuel at the pump for longevity.
Davidson said:rweis, do you have a link for the RASP? Where can I get one? Thanks
The in-tank pump is not moving the fuel through the same lines. It has eliminated a whole section of a very restrictive suction line. It is now sitting on the bottom of the tank. It does not have to draw the fuel through 6ft of very restrictive fuel system and then push it to the VP. If either of you had ever pulled a 2nd gen. fuel module out of the tank you would see why you cannot improve the fuel delivery unless you open up the fuel module first. This is why Mopar tackled this nagging issue from the source IN THE TANK.CFAR said:Everyone covered this pretty well but...
If my stock lp produces 15psi and the new pump 7psi both through virtually the same fuel lines, then the new 7psi lift pump has less volume, period.
Sorry to see you leave California Gary, but I'm happy for you.
That is why it can move more fuel with less pressure. Hope thats the answer to your question.Learguy said:H&P, Do you have the dimensions of the new pump, lines, etc... . ? I have the in-tank, don't want to drop the tank just for exploration.
TIA
Your 150gph pump can supply the VP with plenty of fuel at idle. So the pressure backs up to 23psi. At WOT your 150gph pump can only supply 25gph cause the fuel module plumbing has only about 1/4in feeding your pump. Your pump is rated at 150gph with a 1/2in supply line. It cant move enough fuel through the restrictive fuel module.Fishell said:Gary what did u do to get ur fuel psi up to 23psi at idle? I just installed a fass 150 gph. This is my readings that I get on my gauge. 17 psi idle, 13 psi @ 70-75 mph, but if I stomper down it will go down to about 2-4 psi. This just doesn't seem healthy to me.
I have the common 7 psi at idle, 5 psi cruising, 0 psi wot readings
Your 150gph pump can supply the VP with plenty of fuel at idle. So the pressure backs up to 23psi. At WOT your 150gph pump can only supply 25gph cause the fuel module plumbing has only about 1/4in feeding your pump. Your pump is rated at 150gph with a 1/2in supply line. It cant move enough fuel through the restrictive fuel module.
Huff N Puff said:That is why it can move more fuel with less pressure. Hope thats the answer to your question.
mhenon said:What's the reason it moves more fuel with less pressure??? My fuel line diameter hasn't been changed. It's just that the in-tank pump is at the beginning of the supply line. . not the tail end of it. And, I agree, this is a good thing. I just don't see how you can say more volume of fuel is now moving through this line.
Huff N Puff said:That is why it can move more fuel with less pressure. Hope thats the answer to your question.
I'm not confused at all,There is no suction line on the in tank pump. How can I give you the dimensions of lines that don't exist. The opening of the inlet of the intank pump is about 3/4in. The inlet of the fuel module that feeds the old lift pump,inside diameter is a little over 1/4in.Learguy said:H&P, Thanx for the theory(?) Do you have dimensions????? Not Theory.....![]()