Here's my story... You can't swing a dead cat on any cummins forum without hearing about fuel pressure to the dreaded vp44, I get it and after much reading understand the pay a little now or a lot later situation. So After installing a fuel pressure gauge (discovered importance from same forums) I was appalled to find out I had 8psi at idle and approaching 0psi at wot... Son of a.... Ok clam down, what's the next step? Swap out the lift pump, dooh it's in the tank and who likes dropping a fuel tank. I've reading endlessly about airdog etc pumps and think that's what I need but what about my pump being in the tank... And damn they're expensive. So here's what I did and the rational I used. Did a bunch of reading and turns out the plastic membrane in the vp44 that's tears is because of low pressure not high pressure (supports what I want to do so I continue). Now what about pulling fuel through the crappy in tank pump? Will it burn out a a new pump plumbed In Series.... Well I've read multiple times that the vp can still run, for a short time with a dead lift pump, umm so therefore a pump plumbed in series could also pull fuel through said weak pump ( again supported my end goal so continued). I installed a factory replacement pump on the side of the block (in place of dummy block installed by dodge ) in series with the weak in tank pump and here's the results, 22psi at idle and 15psi at wot. I'm happy and if what I read is true this set up should be fairly robust and I like the fact that if one pump of the other goes out I still have a back up to get home on....

I always have a hard time remember everyone else abuses there truck. In my case there is 0 ZERO rusty bolts.

Abuse doesn't create rusty bolts, climate does. Spend a few years in a humid climate that spreads calcium chloride on the roads, you'll have plenty of rusty bolts to fight.

Do you guys know that the bolts holding the bed on are rusty? You just may be surprised. My truck came from upper Michigan and then spent time in Mn. and the bolts came right out when I lifted the bed. My daughter's truck came from Ohio and the bolts came out easily on hers too.

Couple of things...23 psi out of the front pump is nearly the same pressure ratio increase as 8 psi from a single pump, so your not working it too hard. It may not be able to handle the pressure on seals, but as far as making pressure it's fine. Both are in the 1.5-1.6:1 range. I'm still not sold on the idea, I think you may outflow the intank pump but that might be a rare case.

Ah6, not sure what you're getting at but agree that pump should have been able to handle it. Someone mentioned early that the inlet screen on the intank might be clogged, might be why the second pump burned out....Abuse, maybe, I'm jealous of moparmans monthly inspections...They might not be rusted, your right, I don't really know. My main concern is doing it the easiest way. 2 bolts to drop the tank but you'll have to fuss with the connections between the bed and tank, 6 potentially rusted bolts but you have easy access to the sending unit and connections. Only time will tell how I proceed.One thing I thrilled about for sure, is finally having a good thread going ;)

Like in sizing turbo's, you can only run as much fuel as the primary (in-tank in this case) can flow. The in-tank might not be able to supply the engine mounted pump enough fuel to suffice. I think the in-tank is capable of near 90 GPH when at 0 psi, but that would leave you with only 8 psi to the VP. I think the setup itself can starve the engine mounted pump if you are using your truck for towing and working.

Yes, I think the second pump was starved but during my initial research I found that the intank lift pump has a bypass that will allow the truck to run even with a dead lift pump (not a good idea but possible) I've proved it won't bypass enough to supply a second strong lift pump.I tried to save some money and time and lost. My wife tells me often just to do it right the first time but what does she know anyways....

Are both of those pumps powered off the ECM?I hope they aren't cause I think that's what Dripley was talking about how it burned up his ECM.

Actually neither one of mine were connected to thru the ecm. The intank pump was connected thru a relay Dodge installed with the in tank pump and power came right off the battery IIRC. The booster pump was connected to an oil pressure switch I installed on the driver side of the block with the power off of the battery. I never did figure out what fried my ECM. not that computer savy.

Both were powered off a ECM powered relay....

You guys in the states prolly don't understand how expensive it can be to have parts shipped over the border... But to my utter surprise found a US based website (peak diesel performance) with a shipping depot in Canada so ordered a fass ddrp and relocation kit, which I paid the exchange on and got free shipping, woohoo... Will update when parts arrive and I'm ready for install.

Got my pump and relocate kit. Any tips for install?

send it back and get an airdog ....but seriously, take good care of the electrical . the only trouble i've had out of my airdog was when i had the + and - hooked up to the battery terminals and they got real corroded(i've since cut the wire back and relocated them to the PDB). as some1 said before, all pumps push fluid better and easier than pulling it, so mount it on the frame rail to make its life easier.

I've already got a connector spliced in at a ecm powered relay for the series pump that blew up so I'm just going to use that. Yes, push better then pull, it was moparmans suggestion that if I went with a ddrp to relocate it to the frame rail. I've been noticing since loosing my series pump (and therefore about 10psi of fuel pressure) a small knock I had came back. Would injectors knock with lower fuel pressure?

I would think that there probably would be a slight knock, due to not getting enough fuel at the right time of the injector event, thus creating a knock as the injectors popped off at the wrong time...Kind of like when you have a fuel leak, and the truck is running rough. Wouldn't be enough to create the rough idle, but just enough to create a slight knock. Although it's hard to diagnose a knock on the 12v/early 24v's, since they are kinda noisy anyway! I'm wondering if you had too much of a restriction in your line with your in tank pump going bad, that caused the other stock replacement to burn out quicker...It's better off to not replace the stock pumps with more stockers. It's one of those things, where if something goes out on my truck, I tend to pay the extra money and upgrade, if possible, so I don't have to do it again anytime soon. Personally, as far as getting to the tank, I would much rather take out the bed bolts, especially if you have anything more than 1/8th of a tank. You don't actually have to remove the entire bed, I lifted the front of mine about 1-2 feet, and held it in place with some cribbing, while I messed with all of my fuel lines when I installed the Airdog on my 01. Remember, we have 34 gallon tanks on these trucks, and IIRC, diesel is 6lbs per gallon...the tank itself probably only weights maybe 20-30 lbs dry, but when you start adding 5-10 gallons of diesel left in it, you're talking about supporting 60-100 lbs while you lower it and lift it back up, if you're not completely dry. I'd much rather lift the bed up with a cherry picker, or use 3 friends to lift the bed up and move it to work on the truck. A case of beer as payment is far easier to carry out of the store than to lower a full tank of diesel!

Since your gonna be in there, might as well get some kind of a draw straw too. Not sure if your kit came with one. Otherwise you will still be restricted to the stock tank hardware like I am. I'm still having pressure drop issues because of it....

Yes, unbolting bed is the route I think I'm going to go...I thought my lifters may needed adjusting or injectors cleaning but I see now my knock is caused at lower fuel pressures, thx for the specifics on whats possibly happening^^^Draw straw.... I'm worried about the 1/4 tank issue. Seems like its do to improper install but I saw a vid on utube where a guy replace his intank pump with a hose. I'm not looking to supply fuel for big hp so I think I'll retain the factory sending unit and just remove the pump.

Drawstraw is easy. Lay a quarter in the bottom of the tank and cut the tube flat to fit. This is for a empty tank measurement as you fill the tank it will deflect away from the tip of the tube from the weight of the fuel. Do not cut at angle. you can lightly notch the tip bit no more that 1/16 or 1/8 of inch no more!No 1/4 tank issues here I typically can get right down to the Empty mark.

My ADII came with a kit for replacing the intank pump. It has there version of a draw straw in the module. Both the pump and engine return lines feed back to the fuel basket. I can drain the tank dry. I filled up once and put 34.5 gallons in.

There is a reason draw straw's are not commonplace anymore, they were unreliable. Most of that was installation technique, but not all of it.

My little AD 100 has 3/8" line ran to the connection at the top of the tank. 18 Psi with 2 to 3 psi drop under heavy load. I don't have the pressure drop that other people claim.