Install fuel pump in series with in tank pump

[sir troughs a lot]

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....

[ISX]

Very interesting. I don't know if I would rely on 2 crappy pumps but it obviously works. I don't know if you would ever see me forking over big money either so it will be interesting to see how this works out for you in the long run. Keep a little 2 stroke in it all and it might keep everything happy, including the pumps. Though I would like to hear an explanation of why the OEM pumps fail, is it lube or what? Maybe someone will chime in. I don't think running compound pumps will hurt anything. Maybe the OEM ones are overworked anyways. Sorry this thread has been dead for 3 days with no reply, usually someone always replies within the day but this thread seemed to be pushed down in the abyss.

[Mopar1973Man]

Question what is back in the factory location for a pump? (Brand)

[flagmanruss]

While you are installing the on engine lift pump & have to bleed the system anyways... Did you replaced the tiny banjo fittings with the larger holes or drill the OEM out?

[sir troughs a lot]

Yes 2 crappy pumps, had I had a pump on the side of the block I just would have replaced it, I'm trying to avoid dropping the tank.always use 2 stoke as per moparmans outstanding researchPump brand is Alliant Power?Nope, didn't open up any of the banjos.Put 3hrs of driving on it last weekend and all was good.No worries about ignoring me guys, I only took it personally... ;)

[dripley]

I ran a similar set up for quite a while, probably 3+years. I installed a BD diesel booster pump when I found out the intank pump was putting a little pressure. At the time I did not know the importance of fuel pressure. I installed the booster pump on the frame rail and it was wired to a fuel pressure switch so as not to put to much pressure to the vp while cranking. I ran it that way with no problems and no fuel pressure gauge. I learned all of that later when my ECM crapped out and I found this site trying to solve that problem. I think if you have a gauge and monitor and the pressures stay good you would be ok. Mine worked fine. I guess it depends on how long it holds together.

[sir troughs a lot]

I read about problems with too much pressure to the vp44 during startup, that's why I powered the "new" pump off the ECM powered relay. At start up, my gauge climbs to 5-7 psi then falls back to zero. That's what I thought, maybe not an ideal set up but I'll watch the gauge and worst case there's a filter between the pumps and vp to catch bits from a ____ off pump..

[dripley]

My booster pump came with the oil pressure switch. At the time I did not know the wiring for the block mounted pump was still there.

[sir troughs a lot]

Kaboom, been hearing the block side pump howl every now and then and other day went from 23psi at idle to 5... Pulled the block side pump and now back to the original 8psi at idle I started with. Currently shopping for a permanent solution.

[JAG1]

To save your ECM from burning up from a pump going bad, it's good to start out by planning to have the ECM trigger a relay and power the pump directly off the batteries. A jammed pump can burn the ECM and they are getting harder to get.I'd drop the tank or lift the bed as I think you'll find some of the beginnings of clogged screens inside the module by now. I think some inline pumps even had a real clogger situation in which a small cylindrical shaped screen filter was placed in front of the pump.Better to get rid of the screens and put in a changeable filter like the big rigs but installed before the lift pump.The 1/2'' lines create increased flow and gives freedom to add the prefilter.I don't know this stuff I'm just repeating what I've learned on this forum and how my truck's been good this way.

[dripley]

That sucks. I guess my luck was better than yours.

[diesel4life]

Kaboom, been hearing the block side pump howl every now and the other day went from 23psi at idle to 5... Pulled the block side pump and now back to the original 8psi at idle I stated with. Currently shopping for a permanent solution.

What kind of warranty did it come with? How many miles did it last? I wonder if you got a fluke, or if possibly the 8psi was simply too much pressure for the pump, being they generally see suction and not positive pressure on the inlet side...

[sir troughs a lot]

Not sure of warranty, going to look into that. I installed it early march so it lasted about 4 months and no more then 10,000kms. When I installed the block side pump my common sense said it couldn't be good to create 23psi with a source of 8psi feeding the pump but seemed like quite a few ppl on the forums had had luck doing it, unfortunately not this guy. So it's on to a permanent solution. I don't have any big plans for the truck hp wise just need it to be reliable for work. I wanna remove the intank pump and do a fancy frame mount unit but their pricy, what do you guys recommend for a ddrp?

[Mopar1973Man]

I wouldn't suggest a DDRP pump... The only way I would do that is to buy a big line kit and relocation bracket to move it back by the fuel tank. Pumps are not design to suck fuel a long distance but to push it a long distance so relocate back by the tank with 3/8 or 1/2 inch plumbing then your good.

[sir troughs a lot]

Mike, noticed you run an airdog, is that the configuration you run?

[Killer223]

I also have this set up. when i purchased the truck it had the in-take pump, and the one on the block. they both work. so far.. i've had no problems yet. but i also don't have the beloved fuel pressure gauge. i took my in-tank pump out to clean the screen all was good. the best way to get to the in-tank pump is lift the bed. 6 bolts. then used 2x6 on edge one at front and one at rear. that provided sufficient room to access and remove the pump canister assembly. sorry for the attached thumb nail. i clicked the wrong one and was to late by the time i saw it. i cant find a way to delete it.

[sir troughs a lot]

Ya, that's my next decision, drop the tank or lift the bed. Should prolly get under there and spray all potentially needed fasteners sooner then later seeing as I'm in the rust belt...

[Mopar1973Man]

Drop the tank only requires the 2 bands...

[Killer223]

this is true, but you also have to reach up and disconnect the lines and wireing, my way just disconnect the fill hoses. lift bed. no need to have an empty tank either. both would suffice pending the desired task at hand.

[sir troughs a lot]

Yes, agree rational in above 2 posts. The deciding factor for me will prolly be fighting with 2 rusty bolts or 6...