Lift pump question for Amianthus [Archive]

SoCalDMAX

03-14-2002, 19:25

Amianthus,

IIRC, in a previous post did you mention using a lift pump on your truck? If I'm mistaken, forgive me.

The reason I ask is I've got a new found paranoia! I'm having strong suspicions that making the fuel pump draw a suction from a distant tank is not healthy for it and may lead to increased entrained air, decreased mpg, pump wear and injector wear.

Any ideas for a pump that won't over power the factory pump at idle, provide decent volume at full throttle and allow fuel to pass thru if it fails?

I was thinking of rigging up a high flow/ low pressure pump with a regulator and return line just in front of the factory fuel pump.

Any thoughts, ideas, suggestions? (Besides a long sleeve jacket that straps in the back.)

Regards, Steve

Kennedy

03-14-2002, 20:11

The Cummins (as supplied) does not use a frame or tank mounted lift pump. From what I understand, it is now an intergral (or attached) part of the injection pump much like ours is. As more of these trucks get on in miles, there is an increasing occurrance of lift pump failure which can often take the injection pump with it. I dont follow the Cummins all that closely, but I do see a lot in for service when I visit my buddies at K&S...

I too would be curious as to the addition of a pusher pump. The problem I've seen is that it is tough to find a decent pump that will deliver, last, and not be noisy.

Amianthus

03-15-2002, 09:14

Sorry I didn't reply sooner.

The Cummins does have a frame mounted low pressure pump that draws fuel from the fuel tank and pressurizes it to feed the high pressure injection pump. This pump is what we call the lift pump and it is a truly crap design. It's task is to draw the fuel from the tank (about 8 feet away), pressurize it to about 14 psi, push it through the fuel filter, and into the Bosch VP-44 pump.

The lift pump is made by Carter. The system is supposed to be regulated to no more than 14psi and under no circumstances less than 8 psi. The problem is that this low pressure pump is being tasked with an incredible job. Pumps don't suck, they push. So this design stresses the pump and causes eventual failure. Nobody knows when it will fail, but they usually do.

Kennedy is right that the VP-44 has it's own LP pump internal to it and it will draw some fuel on it's own. But this is separate from the lift pump you are referring to. Not to mention, that sucking fuel through the filter, dead lift pump, hoses, and the tank is not easy to do.

The other downside to this setup is that the VP-44 is lubricated by the fuel it pumps. If the lift pump fails (and it will), you lose lubrication to your pump and it can become toast in short order. This is most people's indication that you have a failed lift pump. That sucks.

Kennedy is also right that the quest has been to find a setup that will pump the right amount of fuel from the tank, be reliable, and not noisy. Several people have done these pusher pump kits and have had good luck. Some use Holley, Carter, and Mallory (seems to be the best for this application so far) pumps. Ted Janetty has a kit that most seem to be satisfied with, not to mention he is a straight shooter when you need information.

I have a fuel gauge on my truck so I know how my lift pump is doing. If you keep the VP-44 supplied with fuel, all will be well. I still have the stock lift pump and it is doing okay (never designed for what I want it to do). I have a few other fuel system modifications to ease the flow of fuel to the VP-44. I keep a close eye on it all the time. I will be installing a pusher pump eventually. Then I should be able to ease my worries.

I wonder why Dmax LTD. decided to use a system like this. I don't see any good reason for sucking fuel from that far away. Entrained air, loss of prime, etc. It just seems like a bad idea. A pusher pump would be in order, in my opinion.

Did that answer your question? If not let me know.

Kennedy

03-15-2002, 11:14

It seems the BB Buick guys (myself included) like the Mallory 110 or 140. I have the 140 on my mudder. It does make noise, but has not leaked, failed or otherwise in 7 years.

The Holleys, from what I hear leak/fail when subjected to continuous duty.

I had a Carter 4954? on my 6.5. It was afirly noisy, but the real problem lies in the fact that when a positive displacement pump quits, it will not allow flow through!!!

I believ GM left off the lift pump as a cost/safety measure as there is no need to have an oil pressure switch/relay system on a mechanical pump.

Amianthus

03-15-2002, 12:38

Yeah, Mallory was probably going to be my pump of choice. I am also going to install some check valves to hopefully address the failure issue. We'll see.

As for the noise, what noise? I wouldn't hear that pump running if my ear was next to it. At least not with the engine running.LOL

SoCalDMAX

03-15-2002, 13:35

Hi guys,

Thanks for the replies!!

Assuming that our fuel systems on our trucks were defect free and working as designed, do either of you feel that this is a design shortcoming that is seriously affecting economy or power?

Enough that Joe Diesel with a stock truck should be looking into it? I have no idea how much those pumps you mentioned cost, but I'm toying with the idea, if you guys think it's really worth it.

I'm all for more power, economy and increased pump and injector life. (I wonder if all of those benefits are gonna be big enough to write home about.)

I'm sure the engineers would love to give us the best they can design, but some bean counter somewhere has the final say.

Regards, Steve

Amianthus

03-15-2002, 14:56

That's a very good question. Normally I would say no, you don't need a pusher pump. But even on the stock Dodges they are failing, so I guess it's up to the individual. But if some are having problems maintaining prime on thier trucks and the dealership is useless, it's something to consider.

Now for those that are hammering more fuel into thier trucks to get more power, a pusher pump will do nothing but help. More fuel out of the pump means you need more fuel going into the pump. It's that simple. I don't know what the capacity of the LP pump for the Dmax is, but if you are going to push the issue, I believe that you should just get the pump. It won't hurt. Anyone else?

DocDyno

03-15-2002, 20:49

Amianthus, Kennedy, SoCal,
One of my projects as an EFI systems development engineer was to develop an in tank pump system for the marine and automotive aftermarket Hi-Perf. industries for new EFI engines. Some of these engine packages output over 500 HP (gas). I have access to pumps, modules, and system components from two of the largest pump/module manufacturers. Should we look into a development project to devise a pusher type system, maybe an in-tank (amianthus is right- pumps are designed to push)that we could validate and offer to others with interest or need. Let me know your thoughts, design criteria, and level of interest.
Doc

SoCalDMAX

03-16-2002, 11:19

I'm VERY interested. I think I can rustle up a factory fuel tank to test with.

In another thread, someone posted that Ford had determined that diesel fumes can be explosive in the right mixture and that's why no one is using an in-tank system.

We'll have to use some connectors that won't allow any sparking at all.

Let us know what you think would be the best design approach, where you want to do it, etc.

Regards, Steve

IndigoDually

03-16-2002, 17:10

Don't most fuel injected gassers have lift pumps in the tank? Gas fumes in a wide range of concentrations are explosive. I don't see this as an issue with diesel either.

DocDyno

03-16-2002, 19:57

SoCalDMAX
Most gassers do have pump-in-tank systems. The 6.0 and 8.1's have a combo lift/pressure pump that outputs ~50-60 gal./hr. for a system that is regulated to 4 BAR (~53 lbs.)
The last time I was at the GM desert proving grounds there were some vendor based fuel system engineers there. It is my recollection that they traveled there in a Ram/Cummins in which they were testing an in-tank "lift" pump. I will try to find out what it was and if it ever made it into any level of production. Having a tank available would be great. I will be in So. Cal- Burbank, Corona, etc. The first week of April working on come calibration projects. Maybe we can hook up and move this project forward.

[ 03-16-2002: Message edited by: DocDyno ]</p>

Kennedy

03-16-2002, 21:15

DocDyno,

Alan is it? Yes, I think it would be interesting to pursue. THEN, a better fuel filter arrangement too. Youd think they could have done a better job of guiding/locating the upper oring!

SoCalDMAX

03-18-2002, 11:59

Hi Guys,

OK, since gasser in-tank pumps are putting out decent flow, but at ~50psi, are there other options for in-tank pumps? Isn't 50psi a little high?

I was thinking along the lines of 10-15psi. Or should we go with a 50psi pump and use a pressure relief and have it dump the rest back into the tank?

Regards, Steve

Amianthus

03-18-2002, 12:59

I doubt that a gasser pump would be able to handle the requirements of the diesel engine. Flow is key for our application. You may not need a ton of pressure, but you will need in the area of 100-150 gph. That's where the Mallory really shines. But that being said, there are other pumps that will move that much flow. The other problem is, can the pump design handle the viscosity and quality of the diesel it is pumping. Some pumps do better than others. I don't know what the mass flow requirements are for the Dmax, but I am almost sure that it is more than a gasser of similar displacement.

DocDyno

03-19-2002, 16:25

There are a lot of choices in pumps and there are a number of canidates that will flow ~150 gal/hr/ at ~5-15 psi. Several of them are available as in-tank units and several are available as frame rail mounts. I will check with some of the systems engineers as to which of these can handle the diesel fuel chemistry and viscosities. I hope we can come up with some positive results. It appears that this system could really be needed. If we can find an OE pump system, I think it can be cost effective. Additionally I think we can come up with a more effective/servicable filter arrangement as John K. suggests. Additionally, it sounds like this could be a real find for our Cummins/Ram friends.

SoCalDMAX

03-19-2002, 17:59

Yup, I think you're absolutely right, anybody with a diesel would benefit from this. I originally read about it on a Ford and a Dodge site.

Drop me a note on your proposed trip schedule to SoCAL, I'll meet up with you. socaldmax@cox.net

Regards, Steve

Kennedy

03-19-2002, 23:11

Frame rail mount!

I'm not taking the friggin tank out when (not if) it fails...

f theyd have just put a better oring retention system on the stock filter, it would work MUCH better!

Biodiesel6.6

04-01-2002, 21:21

Could some of the problems be caused because of partial pluging of the 2 micron filter in the Duramax?
I thought most filter were 10 or 30 microns for filtering diesel fuel? Now I see why we need a lift pump.
Let me know how I can be of any help! tongue.gif

Amianthus

04-02-2002, 09:02

Biodiesel 6.6,

I'm glad you brought this back to the top.

I just had my lift pump fail this last week. The awesome dealership I had, replaced it for me under warranty. Before, I had around 11 psi (post filter / pre HP pump) at idle and around 3-4 psi at WOT. I also had a realy nasty stumble when I got on it. It now has ~14 psi at idle, and around 8 psi WOT. Stumble is all but gone.

I had ordered a pusher pump before it failed, so I decided to install it (frame mount) even though the new pump is in. Now I have around 25 psi at idle and 20 psi at WOT. The stumble is way gone (the truck screams like a violated primate! :D :D :D ) but that is too much pressure for my HP pump. So today I'm gonna modify the system (disconnect stock pump and use it as a spare) so that I get around 16 psi at idle and no less than 12 at WOT.

The pump I am using is a Summit (Aeromotive) pump part # SUM-G3134. My stock lift pump is a Carter pump # P4601HP. (www.summitracing.com)

I don't know how this pump system would react with your commonrail system. But I don't see how a 7 or 15 psi 140GPH pump would cause big problems. Someone else would have to comment on the design specifics for your guys' trucks.

Kennedy

04-02-2002, 10:45

Amianthus,

Have you considered regulating this pump down in psi?

It says free flowing, do you know if it will allow pull through operation if it were to fail?

I do know the Mallory 140 has an adjustable internal bypass that would be handy to turn down the psi.

For the record Dmax guys, it will take a Cummins to drown out the noise from these pumps...

Amianthus

04-02-2002, 11:52

I've regulated it down as much as the integral regulator will allow. Still too much. So I'm gonna retire the stock pump in place as a backup and use the rail mount as my main LP pump.

If it were to fail, there is no way that the stock pump will be able to pull fuel through it. Hence the check valves that I WAS gonna install. Now I'm not going to bother.

These pumps are quieter than you'd think. You really don't even know it's there.

SoCalDMAX

04-20-2003, 12:44

Hi guys.

I've brought this back from the grave because of the recent posts about air in the fuel filters.

I believe the more filtration you have in series, the more restriction you get (ever so slight) and add that in with the entrained air that naturally occurs in diesel, plus potential fitting leaks back by the tank and extreme pressure changes from the common rail fuel system and fuel changing temp in the engine comp. and waddaya get? Air in the hihg point of the fuel system, like the top of the filter.

I'm still thinking of adding a pump right by the fuel tank. But now I'm thinking of removing the stock fuel filter and mounting it after the fuel pump on the frame rail, very close. I'll just extend the factory water sensor wires (is there REALLY an indicator?) then install JK's mega filter right behind that. Then the hose connection that replaces the stock filter under the hood will have a petcock for bleeding, since it is still the highest point.

I figure if I keep the lift pump pressure down around 5-10psi, the factory lift pump should be OK. If I monitor the lift pump pressure and the pump dies, the excess hose length by the lift pump can just be used to bypass it with a screwdriver.

Any comments/suggestions?

CntrlCalDmax

04-20-2003, 19:03

SoCalDMAX

When I added my lift pump I installed a valve on the outside of the frame (easy to get to) that bypasses the pump in case of a pump failure. I have been experimenting with opening the bypass valve just enough to drop the pressure to the engine to 3 psi at idle. WOT it drops to a little under 1 psi. Soon I will be pulling and will see if longer duration of WOT will drop the pressure even more. If so I will close down the bypass a little. My air problem is gone.

chuntag95

04-20-2003, 20:07

CntrlCalDmax,
Did you see any mileage improvement when you added the pump and removed your air problem?

SoCalDMAX

04-20-2003, 23:29

CentralCal,

I looked at your pics, that looks even better than what I was thinking of doing, since the pump is integrated into hte filter mount. If the pump dies, is it possible to replace the pump section alone? Would you mind sharing the specs and part no. for that unit?

Thanks, Steve

earniem

04-21-2003, 00:32

I have been reading the post on booster pumps and need to know more. I have a 2003 that has 1/2" supply lines and 3/8th return. I want to hook up my extra taank with an electric valve but annot find one bigger than a 3/8" supply which I have. I want to put a filter between the tank (each one)and the switching valve. I already have had loss of prime problems and the dealer has changed my rank, a check valve on the pump and then just recently changed the whole pump assembly. I am afraid I to will need a booster pump of some kind to pull the fuel through the filters. My 6.5 had a frame mounted inline pump from the factory. What about something like that? NO I dont want to buy a Transfer flow tank. They would not sell me the instalation kit seperate.

[ 04-21-2003: Message edited by: earniem ]</p>

jbplock

04-21-2003, 06:13

Steve,

Thanks for reviving this topic. I remember reading your comments about the QD connectors and entrained air in one of the early Fuel Filter threads and have been concerned about this ever since. I now have JK's MegaFilter installed and thankfully it IS trapping the air that WAS making it's way to the pump and injectors on my 2003 with only 6.8kmi. Based on Tommy's (a bear) and JK's detective work in tracking down air leaks, I was planning on just replacing all the QD's with hose & clamps. Even if this reduces or eliminates the air I'm seeing, I'm wondering if it would still be good to have the Stanadyne (or similar) filter/lift pump near the tank like CntrlCalDmax and dpearl-river have done (with a filter bypass and oil pressure switch for safety too). Improving the integrity of the fuel line connections will hopefully prevent air from leaking into the system, but it seems like we could still have entrained air that could out-gas as the fuel travels through various restrictions on it's way from the tank to the pump (?). I was thinking I could plumb a Stanadyne filter/pump with hose and clamps between nipple on the tank sender and steel line behind the cooler (not cutting the line which would make it reversible). Any comments? I'm definitely not an expert on diesel fuel systems or fluid mechanics so any words of wisdom are appreciated.
smile.gif

[ 04-21-2003: Message edited by: jbplock ]</p>

SoCalDMAX

04-21-2003, 10:36

Bill,

I'm thinking along the same lines as you. Just disconnect the QD fitting from the tank and put a hose and clamp on that leading to the new pump and filter assy. The other thing I'd like to do is move the factory filter down there as well, so both filters would be close and easy to access.

I'll probably do it in 2 stages. Install the pump/filter assy 1st, and later move the factory filter, although it's not really that big a deal.

Regards, Steve

Kennedy

04-21-2003, 11:17

Word is, that the VP44 pump on the Cummins runs throughout Europe w/o a lift pump, and have a VERY low failure rate. US applications have added lift pumps, and have MUCH higher pump failure rates. This is partially due to failiure of the lift pumps causing severe restriction on the injection pump.

Just what I was told...

Tructh is, there really isn't much out there that can pump diesel continuously AND reliably along with allowing a "pull through" design so as to allow normal operation in the event of failure...

sdaver

04-21-2003, 14:13

hood mounted aux tank with gravity feed(no pump)........we could make it look like a big set of bull horns :D :D :D dave

Amianthus

04-21-2003, 14:53

JK, you're right. There certainly is no magic pump for our application. At least as far as longevity goes.
My Aeromotive pump failed a while back. Actually it just leaked so bad that I took it out of service. I have since replaced it with a PE 4200 model pump. Keep in mind that the stock pump is 70 gph. This PE 4200 is 270 gph. This might be enough for my fueling needs. For now anyway. :D
As for using one in a Dmax, personally, I don't see how it would hurt anything. Although I was talking to Jake99Z71 at our last meeting about some concerns I had with running the dual filter setup that JK is using without a pusher system of some sort. It seems to be doing well, as long as the system is tight. I would think a positive pressure system would be better, IMHO. But I have no doubts that JK has faith in this system. Otherwise he wouldn't run it on his own truck, would he? If it works, go for it.

CntrlCalDmax

04-21-2003, 15:21

chuntag95,
Too early to tell on the milage. All I know for sure is it hasn't gone down.
SoCal,
I installed a 33945 pump/filter and will change the filter to a 33961 6" filter at the first change. I will also leave off the clear fuel bowl option on the bottom of the filter as it looks like it would be easy for something to kick up from a tire and break it. You can install it on the bottom of the filter or not.

I think it is important to install a pressure gauge to monitor the pump output. I hope I will see a problem on the gauge before a complete pump failure. Then I can just open the bypass valve and run on OEM suction until pump replacement.

Kennedy

04-21-2003, 16:00

I really don't think that there is much IF any restriction in the OE system beyond the need to lift from the tank.

The factory gauge shows approx 2" hg at full tank, and 3" hg at empty tank. Pump the primer to show psi, and after it bleeds off (likely through the transfer side of the injection pump) it will stand at approx 2" hg which is likely what the gravity of the fuel in the lines is...

Modified

04-21-2003, 22:49

Just some thoughts.
If we could find a reliable lift pump to mount near the tank, we could maintain a minimal positive pressure in the system at all times, which would prevent sucking air into the system. Then, if we kept the pressure to a minimal amount, and, with the differential pressure across the Mega Filter with the two inch long nipple, wouldn't the entrained air still come out of the fuel, and collect in the top of the clean side of the Mega Filter. We could install a orficed pipe fitting on the clean side vent of the now pressurized secondary fuel filter, and run a hose back somewhere to the fuel tank. This would provide a continuous secondary filter vent of air, with a minimal, acceptable, amount of fuel, out of the top of the filter.
I really like the idea of the Mega Filter, however I still am unsure of mounting any filter ahead of the wheel well or motor, and being exposed in a front end crash. The truck burning in a crash would be my very least concern.
I had thoughts of moving the OEM Filter with heater and level sensor wiring back on the frame, maybe with a reliable lift pump, and trying to fit the Mega Filter where the OEM presently is located. A skid plate under this frame mounted lift pump and relocated OEM Filter could protect them from stones.
These ideas seem to me like they could work, however, I have not had time lately to look under the truck to see if there is room for this. Would this be practical, reliable, and cost effective? Maybe not.
Again, these are just ideas, and hopefully they will spark other ideas, and comments, good or bad.

Burner

04-21-2003, 23:58

OK, get a pump and install it just after the tank. Run a "one inch" line to it for a bath of fuel. Pump that fuel into JK's filter system. Wherever the air arises just port it back to the tank. I think that a floating vertical check valve would work. I did not say to remove or delete the existing fuel line. This line will have two purposes. While the "pump" is working to maintain "X+6" pounds of pressure the original line will, directly after the pump or before the filter, carry the excess psi or fuel back to the tank. If the "pump" fails then original line will resume its first intended purpose. I know that it is a bit of routing but I think it

SoCalDMAX

04-22-2003, 00:46

JK,
I see what you mean, that's why I'd monitor fuel pressure and bypass the lift pump as soon as it dropped off.

CentralCal,
Thanks! I've contacted both Stanadyne dealers in the Sandy Eggo area, #1 said he doesn't have any tech info on the filters and couldn't supply P.N.s, but if I knew the P.N. he might be able to order it. I explained that there is no way to tell which model is which P.N. from the Stanadyne website, and I mistakenly thought he was listed as a distributor on the website. That was a short conversation.

Dealer #2 took down the questions I asked and said he'd call back in a couple of hrs. 8hrs later, no call. I'll check around and see if I can actually find a dealer capable of taking an order. Sheesh, I might have better luck at Burger King...

Modified,
Interesting... so you'd like to continuously vent the bleeder port with an orifice back to the tank. That sounds like it would work pretty good if the orifice is small enough.

Burner,
I had to read yours about 6 times. ;) So you'd plumb in an extra line from the tank to the pump, use a check valve and use the factory fuel pickup line as a bleedoff line back to the tank, If the lift pump failed, it would revert to it's orginal use as a pickup line. Does sound like a bit of spaghetti, but workable if the check valve didn't add too much restriction to the line.

Regards, Steve

a64pilot

04-22-2003, 08:02

Geez guy's,
Anybody ever head of Rube Goldburg?
What's wrong with just running a simple boost pump. If it fails the engine will quit and you by-pass the pump with a 2in piece of steel line or something similar until you replace it.
BTW you would want the pump as close as practible to the tank. If you rubber mounted it with grommets it should not be too loud. The lift pump on my 6.5 could not be heard and it was not rubber mounted and honestly the 6.5 was really a quiet engine. The 6.5 injection pump would pull through the lift pump with the lift pump inop.
Would the stock 6.5 pump be an acceptable pump? If not why not?

jbplock

04-22-2003, 08:33

Not sure if the 6.5 pump would be a good choice. The couplings are designed for 3/8" fuel line (Dmax is 1/2") and the cost is at least $100 or more (for an AC Delco version). They are known to fail after about 50-60kmi on a 6.5 (at least mine did). smile.gif

Kennedy

04-22-2003, 08:42

Running a lift pump may/may not be a good idea. Time will tell. Bosch's stand is that it is not necessary, nor recommended.

Adding a lift pump will pretty much eliminate any suction leaks at the quick cnnects, and as I understand, keep the air entrained in the fuel from "outgassing." Once under pressure, we could also add an automatic air vent, but I really doubt it would be necessary.

The old 6.5 lift pump may well work just fine, but proceed at your own risk. It seemed that the 6.5 could run reasonably well except under heavy load with an inoperative lift pump, so in the event of failure, operation should not cease. I ran a Carter pump on my 6.5 for a few months (#4954?) before it failed and would NOT allow anything above idle speeds until I plumbed in a bypass.