Return style regulator with a aftermarket lift pump

[Bigsaint]

I've been thinking about this topic alot lately, as I have a Mallory 4150 pump and do not have a return regulator (other than the return in the VP44). This is my second Mallory, the first one lasted a whopping 4 months then died. I sent it to Mallory for a post-op, after I conducted one myself, and their analysis stated that the pump died from cavitation (it's a gerator type pump) due to debris. True, my first pre-lift pump filter was really no more than a sediment bowl with no filter, so I chalked it up as a learning experience, upgraded all my inbound lines to braided SS and did away with all of the in bound banjo bolts. I also added a Earl's in line screen filter pre-Mallory. With the help of C. Sutton, I was about to add a return style Mallory regulator (MAA-4309)to help extend the Mallory's life. I decided to give Century Performance a call today and chat a bit about the best location for the regulator. I also had spoken with C. Sutton in regards to this matter and he is of the opinion that it should be right before the injection pump. Not that I doubted Chris and his vast experience with this topic, but I was really more curious if they (Century) had seen more failures of regulators if they were mounted too close to the lift pump. Anyway, I spoke with the same gentleman at Century that I dealt with when I ordered my second Mallory and sent the failed unit back to a few months ago and he is of the opinion that the return in the VP44 is more than adequate to keep the 4150 healthy and that no more than one return should be added in this system with the 4150. Obviously, when running some of the other aftermarket Hi-Flow pumps, a regulator is necessary to control psi's, but the 4150 has a 'dead head' built in to control the psi's. Curious as to what y'all think on this subject.



Scott W.

 

[EMDDIESEL]

So you are saying me having 21psi at the VP44 will not hurt it or either pump?

 

[Bigsaint]

EMD, wish I knew, this is one mans advice, not necessarily mine as for the regulator issue. As to the high psi's and the VP44, Steve St. was the one that spoke with the tech. , not I, so I am going on his word and I surely doubt that he would state other than what he believes to be fact. Again, time will tell but I wouldn't loose anymore sleep than I normally loose over this issue, lol. Clear as mud, eh? We will overcome this issue with more time and experience, we have just entered the proving grounds now.



Scott W.

 

[HVAC]

No Reg

Scott, I have not run a reg with my Mallory and it is still running nicely. If I were to install a reg then I would do so at the engine.



There is a limit to how much pressure the VP44 should see. Of course there has been a debate as to how much supply pressure the VP44 really NEEDS. The later aside, John McIntyre pointed out that there is a seal on the shaft that drives the VP44 that can fail. To much pressure and a failure would fill the crankcase with diesel.

 

[BigDaddy]

Internal VP44 Pressure

Adjacent to the VP44 supply line is the Overflow Valve. “This valve opens at approximately 14 psi and returns fuel to the fuel tank through the fuel return line (FSM). ” Hence, the VP44 will never see internal pressures (in the low-pressure side) greater than 14 psi (approximately) if the overflow valve is working properly.



Doesn’t matter if we have the best lift pump producing 16 psi or adding a pusher pump helping to deliver 21 psi (EMDDIESEL) at the VP44 supply line. Thus the overflow valve is our lift pump’s regulator and any other pump we may add to the fuel system.



If we supply a source of pressure (i. e. Pusher Pump, A1-Lift Pump, etc. ), that will maintain 14 psi at the VP44 inlet, in a WOT condition, this is all we can advantageously achieve.



Therefore, supply pressures exceeding 14 psi and fuel used for cooling the injection pump will be discharged through the Fuel Return Line to the fuel tank. “Because of this, approximately 70 percent of the fuel entering the pump is returned… (FSM)…”



Hope this answers some questions

 

[Bigsaint]

Thanks for the replies, Nowel and Big Daddy. What your saying makes sense, especially when you couple that with the volume/flow testing MoparMuscle and others did earlier. My one and only reason for a return reg. was to help extend the life of the Mallory, apparently it would be wasted time/expense to do so with this pump.



Scott W.

 

[Un-Hemi]

Scott, If it works, don't mess with it. I don't believe that there is anything to be gained by using an external regulator with your present setup... . unless you have further adventures!



BigDaddy, in fact, it is possible to exceed the flow capacity of the 14psi bypass regulator in the VP-44, allowing higher pressures to be present inside the injection pump. That is causing some to see readings at the input to the VP-44 that are substantially higher than 14psi. Although others aren't having any apparent difficulties with pressures above 14psi, I have some concerns about this; I believe that the DC and Cummins engineers balanced the pressure and flow capabilities of the specified lift pump to prevent overloading the bypass regulator.



I previously suggested a solution in another thread, but got little feedback. At present I am unable to test my idea, although I'm willing to discuss it again, if there is interest. There's nothing secret about it. It does use an external regulator, one lift pump, and will deliver any amount of fuel at precisely any pressure it is adjusted to, up to the limitations of the lift pump, and there will always be flow out of the return port.

 

[EMDDIESEL]

Why do i feel more and more that the Pusher Pump was a BAD idea. The whole idea of it to me was to help preserve the stock lift pump and help keep te VP44 supplied with fuel. Now, i am worried about blowing this internal seal out of the injector pump and basically destroying my $4,000 engine which will NOT be covered by my warranty. I would rather change my lift pump at my own cost every year then have to deal with my engine being destroyed AT MY COST.

I do NOT want to mess with any more fuel lines in the engine compartment that a dealer will look at and void my warranty on the spot. (At least they would have to look for the pusher pump and that would be unlikley on a routine visit. ).

I hope somebody will solve all the mysteries now about having TOO much fuel pressure. If not, i may take this thing out.

 

[Bigsaint]

Tommy T, glad to see ya back on line, thanks for the reply!!!!

As to if it's working don't fix it... . only time will tell, only have about 3 months or so on the new Mallory, so far so good. You nailed it when you stated further adventures, my thought, and it's already being done by at least one other member of the TDR, is to try something entirely different rather than replace the Mallory with yet another Mallory, just not sure the High-output pumps will last as a daily driver. Some of the Aeromotive pumps look promising, good psi's/volume, again not my idea, another member's. Most of the 'big guys' require a regulator to set the psi's as they are not a 'dead head' type pump such as the Mallory 4150. Is that the idea you were speaking of ?



Also, I plan on running with the Mallory until it's death, then I will try something a bit more radical. I hope that's a long way from now, but who knows, could be tomorrow.



Scott W.

 

[Bigsaint]

EMD, to quote someone that I dislike... . " I feel your pain". It's starting to get real old, always worrying about FP, watching the gauge at idle and WOT, wondering if today will be the day when I have yet another FP problem when I should just be enjoying the truck.



Scott W.

 

[EMDDIESEL]

EXACTLY how i feel. I cant even enjoy my truck since i am scared its going to die or one of the rubber hoses is going to blow off or who knows what next

 

[Bigsaint]

We need a lift pump support group, lol, " Hi, I'm Scott and I have great concerns that my lift pump is going to take a dirt nap and destroy something very expensive on the best truck that I have ever owned".



Sometimes knowledge is a terrible thing



Scott W.

 

[Bigsaint]

Going along the LPSG ( that's lift pump support group to you)



" It's been 3 months since I installed my last lift pump" . When do I get the merit badge ?????



Scott W.

 

[Un-Hemi]

Why, Thank you, Scott! It's good to be back in the lift pump wars! You see, I've been observing the lift pump dilemma first-hand. I didn't mention in my towing and hauling report that before I left on vacation, I had parked the turbosaurus because it wouldn't pull up a moderate grade at full throttle at over 2100rpm. I changed the fuel filter before embarking on my own adventure to retrieve my POS minivan from Alberta thinking that would solve the problem. Even with the new filter, it would only pull to 2400rpm, and even had a couple of fits of backfiring and burping at full throttle while towing. I backed off after that. In all probability, the lift pump is hooped! I've got a fuel gauge on order; that's the first order of business!



So here's the dilemma. I've got AN-6 to metric adapters. I've got Ray's banjos. I've got lots of ideas... ... . but no time and the minivan need$ at least one head a$$embly. (the end rocker $tand broke right off the head. It'$ a known problem. )



I don't require the Turbosaurus at the moment, so it can sit for a while, and it is driveable if I take it easy. It's also dead stock. Therefore, for the time being, I'm going to bide my time, work on the POS minivan, install my fuel pressure gauge, take some measurements, then get my lift pump changed under warranty, then start bombing the fuel system to see what makes the most difference.



IMHO, there's no one system out there that will satisfy everyone. Budgets are different. Bombing levels are different.



For the majority, probably replacing the stock lift pump with the latest and greatest issue from DC or Cummins and installing a set of Ray's banjos and a fuel pressure gauge will suffice. MM has stated that this works. I suspect that the stock lift pump is quite similar to a Carter 4601HP (I think that's the number), except that it has banjos instead of NPT fittings, and is more expen$ive.



After that, almost anything goes. Scott, you have taken one approach, Big Bob has another idea. They are all valid solutions to the problem. What works for YOU is what works for you.



Relocating the pump seems prudent, as that seems to be the accepted recommendation.



The biggest difficulty seems to be finding a reliable lift pump. Maybe it would be wise to locate the lift pump back by the tank, where it's easy to work on (read... replace), and install the least expensive most common pump that will maintain reasonable pressures at the VP-44. Then, carry a spare, because, of all the things we know about the dumb lift pump, we know it's gonna fail!



My killer system? A pre-filter and a monster pump capable of about 25psi, mounted at the tank, fed by a #10 wire, controlled by the ECM using a HEXFET switching transistor (or two), passing fuel through a 3/8 line directly to the stock filter/heater, then on to an adjustable pressure regulator just before the VP-44. No banjos. Drill out the return flow regulator and replace with a restrictor orfice so that there is always controlled return flow through the VP-44 back to the tank. At that point, it's all up to the regulator. I guarantee that the fuel pressure at the VP-44 will stay rock-solid at whatever pressure you desire, right to the flow limitations of the lift pump. Reliability??? Don't know. Anybody know of a readily available, inexpensive, reliable lift pump with the correct characteristics?



Ah, yes. Another 2-hour post! I'm going to bed. Good night!

 

[BigDaddy]

in fact, it is possible to exceed the flow capacity of the 14psi bypass regulator in the VP-44, allowing higher pressures to be present inside the injection pump. That is causing some to see readings at the input to the VP-44 that are substantially higher than 14psi. Although others aren't having any apparent difficulties with pressures above 14psi, I have some concerns about this; I believe that the DC and Cummins engineers balanced the pressure and flow capabilities of the specified lift pump to prevent overloading the bypass regulator. (TT)/QUOTE]



Tom,

The Overflow Valve is a restrictor type check valve and is located down-stream to the VP44 inlet. It's pressure setting is fixed and will not allow pressures greater than 14 psi to enter the low pressure side of the injection pump.



Inlet pressure to the VP44 could be any number. Let's say 30 psi. The Overflow Valve will only allow the injection pump to use 14 psi of this 30.

There is a limit to how much pressure the VP44 should see. Of course there has been a debate as to how much supply pressure the VP44 really NEEDS. The later aside, John McIntyre pointed out that there is a seal on the shaft that drives the VP44 that can fail. To much pressure and a failure would fill the crankcase with diesel. (HVAC)

I would agree and suspect, if the VP44 pump saw pressure greater than the 14 psi, internal damage may result.

 

[Mopar-muscle]

woo hoo !!!! more lift pump paranioa ....

ya , i know , i started it , i think i will have to buy or borrow a flow meter and do the test that tommy asked for and we didn't do , return flow directly from the VP and from the head , i just hate the idea of hacking all my pretty solid stainless lines to prove a point that no one will remeber 2 days later and get back on the 20 inch fuel line and 500 psi to the VP44 bandwagon ... .



sorry i'm not very subtle when it comes to some things . maybe my truck will run 10's if i do nothing else but spend 10k on my fuel lines and fuel pump ????? i highly doubt it .



to review , incresing pressure at the inlet to the VP44 from 0 psi to 5 psi saw NO increase in fuel being returned to the tank , none , nada , not . 1 GPH .



big daddy , where did you get that drawing ? my understanding is the overflow valve is for the low pressure pump inside the VP44 and not the inlet pressure coming from the lift pump , if it were then you shouldn't see more than 14psi as it would be open all the time with these guys with more than 14psi of pressure .



the stock filter is only capable of flowing 45-60 gph , flowing 110 or 220 is not going to make a bit of difference because you can't get anymore thru it without blowing apart the heater or the filter element .



if you want to add a regulator , good idea for those with more than 14psi , especially at wide open throttle . remember pressure is a restriction to flow after you equalize flow thru all your orifices . dodge speced out the restrictions for a reason , why i have no clue , but i do know i went 14. 9 with a BONE STOCK FUEL SYSTEMbanjos unmodified and all , 0 psi at the injection pump , no stumbles or anything , what am i doing wrong ????



FIRE AWAY

 

[BigDaddy]

Hey John,



Been a long time. Too bad you can't make it the 12th Will catch up with you sooner or later



I did a quick and dirty diagram simply to show the flow of the Overflow Valve. The new diagram (below) shows the pump divided. View this "simplified" diagram if you were standing in front of the truck, on the driver's side.



The overflow valve is adjacent to the VP44 inlet banjo fitting. It is removable and is internally ported to the VP44 inlet and fuel return.



In this updated diagram, let us consider the following hypothetical constants for the low-pressure side of the injection pump:

PSI @ VP44 INLET = 30 PSI

PSI OF COOLING FUEL = 0 PSI



Consequently, the overflow valve will allow only 14 psi to the low-pressure side of the injection pump. The remaining 16 psi is directed to the fuel tank return line.



Then again, if the PSI @ VP44 = 5 psi and PSI OF COOLING FUEL = 0 PSI, there should be 0 psi at the return line.



Therefore, the overflow valve protects the injection pump of pressures greater than 14 psi and doubles as a regulator for the lift pump. No matter how much pressure is supplied to the injection pump inlet.



With this in mind, it is my opinion that any system providing an excess of 14 psi in a WOT condition is unusable.



EMMDIESEL, your injection pump should be safe with your pusher pump.



Joe

 

[Un-Hemi]

BigDaddy, we have different perspectives on how the VP-44 works. It's my contention that the bypass regulator only opens if the VP-44's inlet pressure exceeds 14 psi, allowing the excess fuel to be 'blown off', back to the tank. If the bypass regulator is swamped by a lift pump's ability to deliver fuel at higher pressure, say, 20 psi, then all the fuel circuitry fed by the intake port of the VP-44 will be pressurized at 20 psi. I don't believe that the bypass regulator will be limiting any internal pressure in this circumstance.



It's been stated before that the VP-44 is capable of drawing fuel (operating with a negative head), and is probably happy operating with any positive head pressure at its input, up to 14psi. It probably is adequately cooled by the quantity of fuel that it is pumping through the injectors. As I said above, the bypass regulator is there operating like a pop-off valve on an air compressor, to limit the maximun internal pressure of the VP-44 to 14psi, during periods of low fuel demand.



One of the difficulties with trying to understand how the VP-44 works is that no one admits to having been inside one. About the only thing we know for sure is that it is a 2-stage pump, with a 300 psi primary pump and a 17000psi secondary. Where the fuel actually flows inside it is a mystery, and enquiring minds would like to know. TXram, where are you?



MM, I respect your observations. It's good to have a moderating influence in these discussions; it kinda keeps reality in sight! I've now had first-hand experience with low (probably minus) lift pump pressures and can confirm that it definitely affects truck performance. I appreciate that you have run VERY respectable ETs with your setup and whatever you're doing is working for you. What I fail to understand, is why others are having so much trouble with their lift pumps. Have we lost sight of the original objectives here? Alligators and Swamps come to mind!



It's important to have a lift pump that will have enough overhead to allow it to flow enough fuel at the desired pressure, allowing for all system losses. If we desire perfectly stable fuel pressure at the lift pump, a regulator is needed to compensate for those losses and varying lift pump pressures with flow rate changes. If we desire fuel flow OUT of the return port of the VP-44 at ANY inlet pressure, the 14psi bypass regulator must be replaced by a fixed orfice that will return a fixed amount of fuel at a given pressure back to the tank. Whether this is necessary is not clear.



MM, the reason that you are seeing no difference in the return flow rates between 0 and 5 psi inlet pressures is that the bypass regulator is closed! It doesn't open until approximately 14 psi, so there will be no change in flow states anywhere in the system between those two inlet conditions. In other words, it's out of the circuit, at least as I see it.



BigDaddy's diagram is interesting, as it shows a different take on how the VP-44 operates. I need more evidence that it is indeed correct. BD, is your diagram sourced from Cummins or DC? Can we take it as gospel?



This all started with the group trying to find a reliable lift pump that will maintain positive pressure at the VP-44 under any circumstance. Whether the Mallory is more reliable than the Carter remains to be seen. So far, the jury is out. The only consensus seems to be that the lift pump would be better placed back by the tank. (MM notwithstanding!) There, it would be operating in a more favorable environment as a pusher, and is easier to service.



While I acknowlege that some appear to be making it work, IMHO anyone that has more than 16 psi at the input to the VP-44 would be wise to add a regulator (non-bypass is fine, as long as the lift pump has a built-in regulator, or, as Scott says, a 'dead head' as most do) ahead of the injection pump.



I apologize for being verbose. It's an interesting topic.

 

[BigDaddy]

No end in sight

Tom,



No apologies needed. Our perspectives are different and that in itself contributes to logical reasoning and constructive debate.



I first must state that my opinions and diagrams are based upon my own research and thought. I do not plagiarize and will provide credit for information that I obtain from outside sources. I. e. Factory Service Manual (FSM).



Tom, where is the “bypass regulator” in the VP44? I only know of the Fuel Bypass Solenoid, used with the high-pressure side.



My discussion has concentrated on the low-pressure side of the VP44 and the Overflow Valve’s ability to regulate pressure to the injection pump.

I need more evidence that it is indeed correct. BD, is your diagram sourced from Cummins or DC? Can we take it as gospel?

The diagram is mine. However, as previously stated about the overflow valve, “This valve opens at approximately 14 psi and returns fuel to the fuel tank through the fuel return line (FSM). ” This can be found on page 14-64 of the 2001 FSM. Also see figures 7 & 17 for location.



Although, we all agree (the one’s posting to his thread at least) that the Transfer (Lift) Pump does not provide an adequate supply of fuel to the injection pump, I wanted to include this statement from the FSM; “Fuel from the fuel transfer (lift) pump will always provide more fuel than the fuel injection pump requires. The overflow valve (a check valve) is used to route excess fuel through the fuel return line and back to the fuel tank… The valve opens at approximately 97 kPa (14 psi). ” page 14-69.



Now I may not agree with this, but it provides me with an understanding why the overflow valve is used and what relationship it would have on a fuel pump that DID provide more fuel than the VP44 requires. I. e. Pusher Pump.



That’s enough for now. Sooner or later we will get the cat by the tail.

Keep’em cummins

 

[csutton7]

into the fire I shall dive--first off I didn't explain my system well enuff to Big Saint--sorry about that--but here it is---

gravity fed system -10AN from the bottom of the tank to a BG5000 prefilter and then to a relocated by the tank mega pump(don't need anyone going out and buying something else until I'm satisfied it will work)... . -8AN to a RACOR filter... . -8AN to a TEE which is a straight shot to the Mallory 4309 regulator... . the leg of the tee goes to the VP44 via some -6 & -8AN fitting and from the regulator -8AN back to the tank---



I too am not on the 2 pump band wagon--why would you want two Carter pumps, which keep getting supposedly updated for this job, I don't think Carter is the answer--now let me say if you're afraid of warranty issues then Carterize with one at the stock location and just let Dodge replace them as needed.....



The VP44 doesn't like to suck thru dead gerotor pumps--I know--so have a replacememnt with you... .



I'm with HVAC on the pressure thing--



I think that any pump producing more than 17-18psi should have a regulator with a return system---the VP44 and the 5/16" or so stock return line can only handle so much.....



we may be only able to get a year or so out of any aftermarket pump, I'm hoping we can get more, thus my state of lift pump war and definitely a help group member..... chris