Engine/Transmission (1998.5 - 2002) new spin on LP problem

[Ncostello]

This is FYI to those who have had lift pump problems. I was in at Schied Diesel today and was told of a new product that may well help if not cure failed lift pumps on Dodge 24V specifically.



Now, before you go calling them, there will be an article addressing it in the upcoming issue of TDR. Plus it is not available now, but should be in a couple of weeks. It goes something like this... .



They, in a joint venture with a reputable company that makes fuel pumps and such, have spent the last couple of years understanding why Dodge Cummins 24V LP's fail. In conlcusion, this new device consists of an additional lift type pump along with a filter system, all of which attaches to the engine near the air horn area... easy access. The way I understood it, it draws fuel from the tank much in the same way as the OEM lift pump and filters it, in turn supplying clean slightly pressurized fuel to the OEM lift pump. Fuel debris has been found to be a leading killer of OEM pumps among other things. After it is all said and done, the injector pump will see around 5 psi or so higher than any stock lift pump has ever produced, resulting in increased life spans for the VP44's. All this stuff mounts underhood for protection. And its powder coated for good looks.



I also understood that this was going to be different than just a pusher pump and the 24V engine was in mind during design so reliability and performance should be on que. They have used their own trucks for research with great results.



Now, I in no way am associated with Schied. I just wanted to pass this along since I know it is a problem many have faced. This looks like a great solution and I sure hope it works for them and everyone. Just keep your eyes peeled in the next TDR for their official description of the system. Like I said too, its not available yet, but should be in a couple of weeks. I'll keep checking and let the forum know if I can get my hands on one for my truck. Hats off to Schied for even addressing this issue for the masses.

 

[Gary - K7GLD]

It's good to see commercial attention to this problem - and this, plus a couple of other outfits offering their versions of "fixes" are quite helpful... But it seems the PRIMARY point of this one proposed here, is the added filter - which is what some of us have already done with our "shadetree" mods:



#ad




In addition to the shown filter here, I have adopted the practice of using my added in-bed fuel tank as my primary fuel supply, and pump outta it thru an even larger spin-on fuel filter into the trucks original main tank, then thru the added filter and Carter 4600 pusher pump - thus, my fuel is filtered TWICE before the stock LP even sees it...



This whole setup, exclusive of the additional tank I already had, cost about $95...

 

[15w40]

Ncostello, thanks for the info on the new lift pump. As some of you may know, I have been searching for a couple of years for an answer for the unreliable Carter pump.



I have read with interest all the comments about aftermarket pumps and all the posts about how the stock lift pump fails. My analysis of bad pumps has shown two different failure mechanisms. The most common way these pumps fail is when the internal “spill-over” valve gets weak and drops pressure and fuel volume. Several of the pumps I have dissected show this failure. Other TDR posters have also said that the pump-to-motor, plastic connection failed and the pump had zero pressure. I believe trash could have caused this failure mechanism. No one has reported that the lift pump died because of cavitation erosion of the volute and vanes, although it is commonly believed that the lift pump location is a problem, being too far from the fuel tank.



In my (limited) experience the most common problem is with the spillover valve. This valve is used to limit the maximum pump pressure to about 15 psi and will prevent damage to the motor and brushes at idle when the VP44, turning at low RPM, blocks most of the fuel flow from the lift pump. One of the dead lift pumps I have been experimenting with showed that the pressure could be made to exceed 25 psi by disabling the spillover valve. Although the pump would not last long if run this way, this pump with 70K miles on it is just fine, it is just the spring in the valve that is bad.



Measuring fuel pressure at the input to the VP44 using a solid-state transducer and an oscilloscope has shown that the vane pump inside the VP44 causes some violent pressure fluctuations. Some of you who have connected a fuel pressure gauge to the injection pump have witnessed the gauge vibrating as the VP44 sucks in fuel and then stops drawing fuel as a vane of the internal pump swings by the input port. It is these pressure fluctuations that weaken and damage the lift pump. It is like I was repeatedly blocking and unblocking the output of the lift pump. When this happens the spillover valve in the pump will open and close in concert with the inlet vane pump in the VP44. The fuel filter between the lift pump and VP44 does not damp out these pressure fluctuations.



I hope Schied Diesel spends some time testing the new pump to insure it can survive the constant pounding it will receive from the injection pump. I am getting tired working with the Carter pumps.

 

[Gary - K7GLD]

"Some of you who have connected a fuel pressure gauge to the injection pump have witnessed the gauge vibrating as the VP44 sucks in fuel and then stops drawing fuel as a vane of the internal pump swings by the input port. It is these pressure fluctuations that weaken and damage the lift pump. "



IF what you say is correct as to rapid VP44 pulses damaging the stock LP, then perhaps the so-called "snubbers" some fellas are using to prevent fuel pressure guage fluctuation might ALSO protect the LP? OR, perhaps, for those NOT having a guage, maybe the snubber ALONE is a good investment?



My own setup, using a length of air conditioner freon service tubing and fitting screwed directly to the existing Schrader valve, and then to the electric sending unit for a 30 psi Westach fuel pressure guage is rock steady, other than normal pressure variations dictated by speed and load...



#ad




Here's the other end...



#ad

 

[A Johnson]

Gary, the lift pump would have to push the fuel through a pretty small hole on any snubber that would be effective, therefore actually starving the VP-44 of the volume needed.



The rubber line you are using more than likely absorbs some of the pulsations, also your sending unit may have a "snubber" built in, in that the actual hole in the end of the sending unit is very small in comparison to the inside diameter of the VP-44 supply lines.



I picked up a gauge snubber for a project I'm working on and the orifice was less than a 1/64 drill bit. ( I'm guessing I didn't measure it)



Just my thoughts-------- A Johnson

 

[Gary - K7GLD]

"Gary, the lift pump would have to push the fuel through a pretty small hole on any snubber that would be effective, therefore actually starving the VP-44 of the volume needed. "



No, you don't get it - the "snubber" isn't IN LINE with the fuel flow from the LP to the VP44 - it merely provides a "side street", flexible reservoir OFF the fuel line to dampen and absorb VP44 pulsations EXACTLY like the snubber line used from the existing fuel line to the guage or sender as many here are using them - and as in the above pictures I posted, the rubber line to my sending unit IS the snubber! In the case of a snubber line alone, used to absorb VP44 pulses, simply omit the guage sending unit, and PLUG OFF the end of the snubber line... Capeesh?



BUT, of course, a larger diameter flexible rubber line running between the existing fuel filter and the VP44 SHOULD also provide enough flexible dampening to smooth out pulsations as well...

 

[A Johnson]

" Capeesh"



I do now. I just wasn't thinking. And I went back and re read your post (sorry). Yes, you make perfect sense.



I guess I need to see it for myself, because if what 15-40 is saying is true and the pulsations are going clear back through the filter to the lift pump, then I would think there is enough rubber line in between to take out the pulsations, but perhaps not. Ive measured alot of lift pump pressures but always with a rubber line. I'm going to try it with a hard line and see what I get.



A Johnson

 

[Bigsaint]

That's interesting, to say the least. I wonder what pump they have chosen to suck the fuel ? Must be some type of vaned design, no way a gerator design could do it ? If I read it right, it will be mounted in the engine compartment, even higher than the OEM design that isn't lasting. Higher equals less to non-existent gravity feed. Personally, I'm not so convinced that debris is causing the vaned pumps to fail. Sure. it can play a part, but it's the sucking rather than pushing that is killing these pumps IMHO.



I'm not an expert, but I'd personally stay away from another pump that sucking fuel. I can't see how that second pump is going to last. Even if it didn't rely on diesel fuel for lubrication, without a motor build for continous duty it just wont last.



I am in now way knocking you, Ncostello. Just giving my point of view. Unless I missed something I think this is another band aid approach for a cure. If you want to run two pumps, at least put the second pump back by the tank and below the bottom of the tank to give it a fighting chance.



Scott W.

 

[JTroiano]

Just for more info. I have two rubber grease gun hoses and then a small copper line going to my fuel pressure gauge and at a certen rpm it makes a horrible buzzing noise. So I think the pump pulses are still there and are really bad depending on rpm's. . I am just driving around with an extra Carter pump in the back of the truck. I had a brand new Carter pump break the little plastic piece between the motor and pump. Piecs of s**t. I don't know what to do. Mechanical pump?

Jon T

 

[Ncostello]

I went to Schied today and they showed me the whole kit as will be marketed. Tis true, mounts on the engine and looks like the pump will be higher than the stock lift pump. It has a spin on fuel filter. It has what looked like a rotary vane pump. Guy did say that it was designed to draw or suck in fuel from the tank. Came with all hoses, clamps, fittings etc to make it work.



For what its worth, this pump setup was run for 6 months straight, 24/7 with not a sign of let up or loss. Now I dont know the test parameters, tank elevation, pressure head to pump against, etc, but it seems to be a continuous duty pump. Thats good.



Who knows... maybe it will work. Maybe I can get them to use my truck for the first one available to the public... kinda like free advertising... hehe.

 

[fest3er]

Originally posted by 15w40
Ncostello, thanks for the info on the new lift pump. As some of you may know, I have been searching for a couple of years for an answer for the unreliable Carter pump.

[Analysis cut for brevity]

...

I'd been wondering about this. Having seen a failed lift pump disassembled, it seemed the pumping mechanism was just fine. That would leave the pressure relief valve as the cause of low output pressure.

To 'solve' the problem, a plumber is needed. Do we have any among us?

If you want to experiment, try putting a T fitting inline after the LP's output, and aim the T upward. Attach a 6" length of hard line, and fill it half full with fuel. Then plug the free end of the line. In household plumbing, this is known as an 'anti-hammer', I think. This should be enough to absorb the nasty pressure spikes the VP-44 causes.

If this actually does work, the proper solution would involve a tube with a polished bore and some sort of o-ringed device separating the fuel from the air. Total length shoulnd't need to be more than 6", I suppose.

Just a thought from a 12 valver with too much time on his hands.

Fest3er

 

[Ncostello]

I just think the whole thing is OK, it just needs to be about three times as big. I would think bigger would be better to absorb the shock cycles and would take some of the load off the small components inside the pump. Too much work for such a small unit. The elevation of the pump compared to the tank should really put little load on the suction side of the pump. IT should be designed to pump like that. It looks like with an empty tank, it would only have to lift about 12". Heck, small fire pumps can pump water up a 20 foot vertical lift. Thats not much, but it is for such a small pump. Who wants to design an exact replica only 3X the size?



Seriously, it just looks too small. And tiny dirt and crud particles are big to a small pump. How hot does it get when under full continuous load?? Heat buildup is killer too. Just thinking out loud.

 

[Mark_Kendrick]

My FP sender functions as the 'anti-hammer' you describe. I have 2+ft of hose that I did not bleed when I attached the sender. The stock pump went out 20kmi ago. No problems since.



I also added weber fittings and #6 ANs. FP went up by 2psi and WOT fp is less than 2psi off idle. . even with showerheads and twins



FWIW,

Mark

 

[Rockcrusher]

Originally posted by A Johnson

Gary, the lift pump would have to push the fuel through a pretty small hole on any snubber that would be effective, therefore actually starving the VP-44 of the volume needed.



The rubber line you are using more than likely absorbs some of the pulsations, also your sending unit may have a "snubber" built in, in that the actual hole in the end of the sending unit is very small in comparison to the inside diameter of the VP-44 supply lines.



I picked up a gauge snubber for a project I'm working on and the orifice was less than a 1/64 drill bit. ( I'm guessing I didn't measure it)



Just my thoughts-------- A Johnson

Has the Diesel fuel affected the freon hoses? I finally got my fuel pressure kit from Geno's and am getting ready to hook it up. I see some use grease gun hoses or whatever. Want to use a good one.

 

[Gary - K7GLD]

"Has the Diesel fuel affected the freon hoses?"



Not that I am aware of - and I wouldn't expect it to - I'm using proffesional grade stuff, and those lines are made to see the flow of refrigerants and the lube oil it also carries to lube compressor pumps - But I've been thinking that taking a small piece and placing it in a small jar of diesel oil might make a good reassuring check...

 

[MarkF]

I had a fuel pressure guage that was fluttering and buzzing like crazy. Connected via a braided stainless line to a drilled banjo bolt that replaced the stock banjo with the schrader fitting. The vendor I bought the guage from was kind enough to swap a new one with me at no charge and suggested I place the stock banjo with the schrader fitting in the botom of the fuel filter housing and swap the banjo from the bottom of the housing into the fitting the schrader one originally resided. Thought was, this may prevent another guage failure. So I insalled it this way and we'll see what happens.

On the flip side my LP is starting to go "Tango Uniform:-laf " (love that family stuff) So now I'm mulling over ditching the LP and putting in a pusher, or giving the "latest" Cummins LP a try. Current LP has 37k on it, I have no desire to mess with the dealer, it will cost me more than the $140 pump in lost time waiting for them to mess with it. And to answer your next question: I'm seeing a healthy 14 at idle, but under WOT with comp on 3X5 it is dipping below 5 psi.

The pump still had enough knads to re-prime the fuel system without having to crack injector lines. I used the open the filter canister let the LP fill the filter housing with fuel method, bumped it 5 or 6 times and she started right up with a few extra cranks.



my . 02 feel free to ask for change

 

[Bigsaint]

That's good info that the pump is of a vaned design, no way a gerator pump would last long at all. If it has a motor built for continous duty that's another plus. The only place I still see a problem is the pumps lubrication. Every time you start the truck, after it has sit for a while, the pump will be initially starting dry with no lubrication until it sucks the fuel up from the line. I can't see how it will be a long lived design. 6 months isn't bad, but at least one year of continous duty would be better as a test IMHO. It would be real interesting to find out what pump they are using. Thanks for the update !!! It's all about R+D, if we all keep trying, someone is bound to hit on a solution that will last and is easy to install/maintain. It's no secret that I'm not big on two lift pumps, but that's just me. Do whatever you are comfortable with and don't be afraid to try something un-tested, that's how we all learn. I'd hazard a guess that there is a single pump that will work well with no more mods. needed other than mounting it back by the tank and powering the pump off a relay. Problem is that it takes one year of testing at a minimum before you can get excited.



Scott W.

 

[Big White Beast]

VP hammering.....

Here is a thread I started a while back about the VP hammering.



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=49673



After checking on air gaps with a few distributors none seemed to think it would be feasible on a quick moving truck. They use them on ships and the slow rolling movement doesn't effect it. It also has to be at the highest point in the system. Up near the hood for us.



My first LP went out at 26K miles. That's when I added a pusher to the system. It's a Carter 4070 high volume low pressure pump. Carters instructions clearly state that to keep the warranty you have to add a filter prior to the pump. I'm not saying that's the major cause of failure to the LP's but it surely doesn't help.



As Bigsaint said only time will tell how this set up holds up.



As a side note. I have a similar filter to what Gary shows in his pic. My first one plugged after 6 tanks or so and the second isn't far behind. So I'll be looking for a better set up soon for pre pump filtration.



Garrett

 

[kaffine krazed]

How about using a spring or nitrogen filed accumalator to dampen the pulsation from the VP-44?

 

[RADdodge]

Garrett – For filtering before the pusher pump, I would recommend the Racor filter. I used the 6 series with the 45 gph spin-on filter (hence Racor 645). If 45 gph is too low for someone’s application, they have 60 and 90 gph spin-on filters so it’s easy to increase the fuel flow. The filters get taller the higher the gph rate however. I have a couple of pictures of the set-up with descriptions on the Reader’s Rigs pages.



A damper would be good insurance if one that operated at 20 psi could be found.