Engine/Transmission (1998.5 - 2002) Wanna fix your lift pump problems?

[Diesel Freak]

I guess I have not been clear.



there is a "potential" for a possible 200 GPH "free flow", but since the pumps only make 15 psi, there will not be any more flow through the VP44.



All this system should do is raise my fuel pressure at WOT from 9 PSI to 12-13 PSI on my truck.



Idle pressure should be the same as it is now.

 

[Behr]

85CJ... . want to thank you for clearing up that terminology question. I had a gut feeling that the name is given to the pump based on its location... . but just was not totally sure. I thought maybe a PUSHER pump had something different internally.



KRS..... I like your theory... . and makes good sense.



I am now debating whether to just buy a new OEM pump from Cummins / Dodge and mounting it closer to the tank and lower then run over-sized lines directly to the filter. I would prefer to just leave the factory pump there un-used. Just cap off the ends to keep dirt out.



I am not sure if there would be a real advantage to having two pumps. Disadvantage of having two pumps in my thinking is that if one of them fails (for what-ever reason) then that would produce a possible OBSTRUCTION..... and that would bring us right back to where we started from.



Gordon... ...

 

[Whitmore]

In my mind





oem set up = lift pump = 50% reliable



oem pump moved back by tank = pusher pump =75% reliable



oem pump moved back and below fuel source = supply pump= 90% reliable

 

[Gary - K7GLD]

IS it "paranoid" to take steps to avoid a well known weakness, or premature failure? Perhaps - but I take the SAME steps in carrying a SPARE TIRE in my truck! The relatively high failure rate of lift pumps is now well known and documented - AND also relatively easy and inexpensive to delay or absolutely AVOID! These pumps (or ANY of the other replacement types!), even when of excellent quality, and without complicating factors such as dirty fuel and poor installed location, WILL eventually fail and need replacement - the BEST we can hope for, is to DELAY that event as long as possible, and MONITOR system operation as to be aware when that time comes - the same as we monitor coolent temperature and oil pressure!



"Paranoid?" - OK, if you insist - but it's now one less thing I need give much more than an occasional glance - even WAY out in the boondocks...



====

"Disadvantage of having two pumps in my thinking is that if one of them fails (for what-ever reason) then that would produce a possible OBSTRUCTION..... and that would bring us right back to where we started from. "

====



Perhaps - UNLESS you do THIS:



#ad




And installed:



#ad




You will note the bypass AROUND the added pusher pump, that slightly reduces total system PSI down to a reasonable level - 21 PSI or so at idle, 20 at cruise, 16 at WOT up a grade towing our 5er, and Comp on 5x5... IF that pump should shut down or fail, the included bypass valve opens under suction, allowing nearly full fuel flow AROUND the added pusher:



#ad




This scheme has resulted in less strain on the pusher, since it's working against less head pressure - and the same for the stock LP, since it no longer has to work so hard pulling the fuel all on its own - and NO intervention is required IF the added pusher fails - the included valve functions all on its own... AND, since MANY stock LP's apparently still allow sufficient fuel flow after failing that their owners aren't even aware of their failure, I'm pretty comfortable that if my stock LP fails, the pusher - along with the mechanical LP built in to the VP-44 itself, will still keep me moving... But of course, there's ALSO the SPARE LP I carry back in my toolbox...



"Paranoid?" - ME?...



NAHHhhhh - just cautious and PREPARED!

 

[Chipstien]

Originally posted by Diesel Freak

here is my idea



a possible 200 GPH free flow, and 15 psi

DF, this is exactly what I am in the process of doing. I still dont know why people haven't tried this yet. Wish me luck... . hope to have it done in a couple of days.

 

[Whitmore]

Gary , it is obvious that alot of thought went into your system but with all due respect you now have a lift pump and a pusher pump, all you did was to transfer the vacumn to a different pump, you are correct that this will help the life of your oem L/P because it is being supplied with fuel instead of pulling fuel however your new pump now has the vacumn on it, so the opertunity for failure is still ther but with it being back by the tank that failure potential is less.



This type of system is exactly what I am trying to avoid. Sorry Gary but IMHO



In my mind





oem set up = lift pump = 50% reliable



oem pump moved back by tank = pusher pump =75% reliable



oem pump moved back and below fuel source = supply pump= 90% reliable

 

[Gary - K7GLD]

NO, my pusher does NOT have a vacuum applied to it STILL is providing about 5 PSI pressure to the stock LP - and isn't sucking more than the 24 inches or so to the tank - MOST of which sits HIGHER in fuel level than the pusher... The point of the bypass and valve arrangement AROUND the added pusher, is only to slightly REDUCE the pressure from it, to the stock pump, since without the bypass/valve arrangement, I was getting 26 PSI at the VP-44 inlet - too high for my comfort! My setup has reduced that to about 21-22 psi at idle, STILL applies positive pressure to the stock LP, and now provides a bypass fuel route in CASE the added pusher fails. I can unplug the relay that supplies power to the added pusher, and STILL get 16 psi at the VP-44 at idle, even though the stock LP is now pulling fuel AROUND the added pusher.



As far as *I* am concerned, it's a FAR better setup than stock - and also better than simply adding a pusher WITHOUT the bypass = but to each his own, and time will tell...

 

[Whitmore]

I think I will go camping at Wolly Worlds parking lot

 

[mgoncalves]

I think a combination of Gary's and Kevin's setups would be the ticket. How about one pump below the fuel source with a bypass so that it never puts out more than 16-17 psi. Add bigger fuel lines so they flow enough fuel so the pressure never drops.



It doesn't seem like it should be difficult to set up a pump with a positive head pressure (or minimal suction required) . We could just use more pump with a regulator type bypass. This way we can have exactly the psi at the pump that we want.





Why are we letting this thing kick us in the rears?









Matt

 

[PLaFrombois]

When is everyone getting together for a huge gathering of L. P. bombing fixes? I have to replace mine next week because of low pressures.

Paul

 

[Rockcrusher]

Amazing how the old mechanical "lift" pumps worked without any problems. I ran over 200,000 miles before I finally replaced it as 'preventive maintenance' on my old '90 CTD.

On my new 2002, fuel pressure was consistant at @12 psi but now its steady at 22. I think Genos sending unit might be haywire. Need to check it with direct mechanical gauge.



By the way, for any of you guys in so Calif, Frahm Dodge in Norco gives excellent service. Service manager Don is very conscientous and takes good care of the cusomers. I know thats rare today.

 

[Whitmore]

Originally posted by mgoncalves

I think a combination of Gary's and Kevin's setups would be the ticket. How about one pump below the fuel source with a bypass so that it never puts out more than 16-17 psi. Add bigger fuel lines so they flow enough fuel so the pressure never drops.



It doesn't seem like it should be difficult to set up a pump with a positive head pressure (or minimal suction required) . We could just use more pump with a regulator type bypass. This way we can have exactly the psi at the pump that we want.





Why are we letting this thing kick us in the rears?









Matt

Thats exactly why I brought this to light . I have a system in place that requires 1 pump and the pressure is fine, it is so simple , no need for 2 pumps ,bypasses and all the mumbo jumbo . The more crap ya throw at it the better your chances of problems.



No since in trying to reinvent the wheel, there are a gagillion pumps in the world that work just like this.



I work in a billion dollar plant where we have every concievable type of pumping that a person can imagine and the ONLY time we use pumps in a series is if we are staging pressures anywhere from 4 psi at suction and up to 1300psi at discharge and the ONLY reason we series pumps in this case is because we run far out on the pump curve and then do it again on the next pump. We have constant battles with the seried pumps fighting with each other . Heck the pumping loops that are 1 pump only are fat and happy. No problems. KISS = keep it simple stupid , I like it that way.



Rock on, Kevin

 

[Gary - K7GLD]

I'm sure we ALL realize and agree that a SINGLE, reliable pump - placed as near as possible to the fuel supply and as low as possible in relation to fuel level IS the way to go - THAT isn't the problem!



The problem is FINDING that failure-proof, indestructible pump for that use!



Virtually EVERY "miracle pump" that has come down the pike, and been touted as the "latest and greatest", HAS failed - maybe not as quickly as the Carters - but then, MANY of THEM last over 100,000 miles as well! Some of us like to blast DC and Cummins for THEIR choice of pumps - YET, we really haven't seemed to be able to do any better - even with pumps costing TWICE as much as the Carters - maybe we should cut DC and Cummins some slack, untill WE can find that "magic" indestructible pump that they couldn't...



FIND a pump that WILL NOT fail - guaranteed for at least 500,000 miles, and at a reasonable price - and *I* will be one of the FIRST in line to buy and install one...



Until THEN, my seriesed Carters will hafta do the job for me...

 

[Whitmore]

the pump is on a constant vacumn from pulling up to 2 feet and from up to 8 feet away, there is not a pump on the market that will survive this kind of application or punishment.



A quote from my original thread... ... ... ... ... ... ... ... ... ... ... GARY ITS NOT THE PUMP



Or do I have to get Wyo Jim in here????????????



Pump failures have been diagnosed as follows



Worn rotors and brushes- maybe to much load from all that vacumn



coupling breaks- maybe to much load from all that vacumn



spillback spring sticking open partially



Do ya think a positive head pressure supplied to the pump will reduce the load on the pump? OF COURSE IT WILL and the results are THE PUMP WILL HAVE LESS LOAD (work) AND LAST LONGER



Try to be simple and come up with something new that has proven reliability and somebody has to throw a wrench and a few other pieces into it.





Kevin

 

[Pit Bull]

Originally posted by Gary - KJ6Q



I'm pretty comfortable that if my stock LP fails, the pusher - along with the mechanical LP built in to the VP-44 itself, will still keep me moving... But of course, there's ALSO the SPARE LP I carry back in my toolbox...



"Paranoid?" - ME?...



NAHHhhhh - just cautious and PREPARED!

Looks like a case of belt and suspenders :-laf Do you ever have dreams of being naked in public?



All kidding aside, it looks like a good plan. Wish I was talented enough to do the same.

 

[mgoncalves]

Kevin, I like your setup, I really do. The only point I am trying to make is, why not have a bigger pump than you need and just let it blow the excess pressure back in to the tank. I think the best condition for our VP 44's is to have 15psi at the inlet at any rpm or load. Why not use a regulator with a bigger pump than what we need? It wouldn't be complicated, and combined with positive inlet pressure to the pump, it should be just about fail proof. I really don't think two pumps are needed to move as much fuel as we use, and totally agree that trying to make two pumps work together is pretty tough.



It sounds so simple to me. What am I missing here guys? Why won't this work? I am by no means an expert on hydraulics, so I am probably overlooking a few things here.



Hang in there Kevin and Gary, some day we will all laugh at the problems associated with the stock lift pump arrangement.



Matt

 

[Behr]

Ok... . time to put my nickel's worth of comments now... .



As someone said earlier in this thread or another related thread... . were not trying to re-invent the wheel. What we need to do is take the wheel in for balancing... . in other words lets fine tune the lift pump problem or

we should be saying lets fine tune the "fuel delivery problem"



What I have come to the conclusion is:



1 - Install a new OEM pump back as "CLOSE" to the tank as possible.

2 - Try to keep the pump as :LOW" as reasonably possible.

3 - Install "LARGER" delivery fuel lines from the pump to the filter.

4 - Also install a "LARGER" delivery line from the filter to the VP44.

5 - Install a "FUEL PRESSURE GUAGE"

6 - Make sure you use brand name fuels..... be leary of no-name diesel / gas bars..... etc

7 - Because of low sulfur fuel use some kind of additive that will give you the extra lubricity that is so desperately needed by the VP44

8 - Change your fuel filter regularly.

9 - Keep a spare OEM lift-pump in your truck. (Your truck has a spare tire... . well... . for now I suggest carrying a spare pump.



You know what the best part is... ??? You know darn well that as long as you have that spare pump in your truck... . the one thats doing the pumping will not break down... ... "Murphy's Law"



My suggestion is..... because it is simple... . I will try this first... . who knows... . it may just turn out to be the cure of all.



Keep it simple... . less things to go wrong... . Oo.





Gordon

 

[mgoncalves]

Originally posted by Behr





You know what the best part is... ??? You know darn well that as long as you have that spare pump in your truck... . the one thats doing the pumping will not break down... ... "Murphy's Law"









Gordon

You are 100% correct

 

[Ncostello]

Behr... after thinking this over for close to a year and reading most all there is here on the topic... what you mentioned is what I'm doing too. What you want to do is well worth your effort and you wont be making any mistake doing it. As far as it solving the entire "problem" or being the best solution remains unclear to me. For I'm not exactly sure any one person can say, with 100% certainty, why these pumps fail at times. Not all have the exact same problem... while on the other hand some haven't failed in 150,000 miles. Pushers work, PE pumps work, moving the stock pumps work. At least were all doing something we feel is better than what we bought.



I originally wrote a response that was about three printed pages long discussing the reasons why the stock oem pump is ok for this job... and how sliding vane pumps in general are inherently good dependable, powerful pumps capable of making good vacuum and lifting liquids without hesitation... yet we still see failures with our example. But I didn't think it would be appropriate to post a research thesis here. I've got a spare pump and want to perform some experiments with it... things like max lift capabilities, max output, full bypass runs... basically try to destroy it in a controlled environment. Maybe this would be a good time to start my first web page with writeups, theorys, and test data. Maybe call it liftpump.com

 

[terrywerm]

Before you tap the bottom of your stock fuel tank....

I think that moving the pump to a location that is closer to the tank and below it is a great solution. This is the preferred method with ANY kind of pump, but in some applications it isn't always possible. Thankfully, in our situation it is.



Somebody made mention of tapping the bottom of the stock fuel tank and adding a bottom draw fuel line in place of the factory top draw line. There are a few reasons why that step is not necessary and will be of no help, and I will explain it the simplest way I can, and have also included a drawing that should be helpful.



I am sure that we are all familiar with a what a siphon is, and a top draw fuel line is exactly that. As long as the line is full of liquid and the outlet end is below the liquid level, there will be positive head (pressure due to gravity) and the liquid will flow. The fuel in the portion of the line that is above the fuel level in the tank creates an upside 'U' and is essentially the same thing as an upside down water level. The fuel moving down at 'X' in the drawing balances out the fuel moving up at 'Y'. Gravity, not the pump, is essentially lifting the fuel at 'Y'.



We all know that all points in a liquid system that are at the same elevation will be at equal pressure or head due to gravity. This is true whether the point is in the storage tank or in a line attached to the tank. For purposes of simplicity, let's assume that the fuel in one inch of fuel line weighs one ounce. In the drawing, you can see that the effective pressure or head at the fuel level would be zero, points above it would be negative, and points below the fuel level would be at positive pressure. In the drawing, the pressure at 'A' and 'B' (pump inlets) would be 5 ounces. As the fuel level in the tank drops, the pressure would drop also, but there would always be positive pressure at the pump inlet, even if using the top draw line. Due to the relatively low pressure differentials we're dealing with here, the outlet pressure of the pump will be unaffected by the inlet pressure, as long as we have a positive inlet pressure. This means the pump needs to be below the fuel tank.



I felt it was important to add this bit of information so that if some of you are considering doing surgery on your stock fuel tank rather than using the original top draw, you will be able to see and understand that doing so would give you no advantage, and would make no difference in how hard your pump has to work, or how long it will last. Increasing the inside diameter of the fuel line would be helpful as it would reduce the resistance to flow in the line, but changing the location the fuel is drawn from would not help a thing. Adding a bottom draw does also add the risk of accidentally shearing the fittings off of the bottom of the fuel tank, causing a fuel spill. Fuel spills are EXPENSIVE to have cleaned up, and I don't think any of us wants to find out through first hand experience!