No Pressure from in-tank fuel pump?

dodgeplowman21

dodgeplowman21

Smokin' Rubber
Joined
Dec 29, 2007
Messages
60
So is this correct. The in tank fuel pump feeds fuel to the lift pump. The lift pump fills the fuel filter which also feeds to the injection pump. Injection pump goes to fuel rail, and so on. I disconnect the line coming from the fuel tank to the inlet of the lift pump, and no fuel comes out of that line. Is that how it should work, or does the lift pump create a vacuum effect to get the fuel out of the tank. I'm thinking my in tank fuel pump is out...
 
Some 3rd gens didn't come with in-tank LPs...

If you have one on the fuel filter, then you most likely don't have one in the tank...

You should only have one lift pump...either its in the tank or its on the fuel filter...

steved
 
Well there is definitlily something there. Auto zone and Advanced auto both sell the in tank fuel pumps. Wasn't sure what was up with that. So does the lift pump suck fuel straight from the tank? Therefore making the lift pump my 'main' fuel pump...
 
Depending on the year of your truck, it might have it on the filter. My understanding is once that fails the dealer will put an intank pump. I currently have the in tank on my 06. I will be switching to a FASS ASAP.
 
I know there is a lift pump on the back of the fuel filter. I have already replaced that. I am just trying to figure out if there is another pump in the tank to help feed fuel to the lift pump, or if the lift pump pulls fuel straight from the tank. Advanced and Auto Zone say there is a pump in the tank as well. They say it is just a fuel pump. Not a transfer pump or anything.
 
dodgeplowman21 said:
I know there is a lift pump on the back of the fuel filter. I have already replaced that. I am just trying to figure out if there is another pump in the tank to help feed fuel to the lift pump, or if the lift pump pulls fuel straight from the tank. Advanced and Auto Zone say there is a pump in the tank as well. They say it is just a fuel pump. Not a transfer pump or anything.
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Ask to see their book, I have a feeling they're looking at the gas option here.
 
I was standing at the counter and they selected the diesel option. Both one has a 6 in the vin, the other has a C in it. They both say there is a fuel pump in the tank. I got a haynes, I'm gonna check tht out and see what it says.
 
If you have the filter mounted pump, you most likely do not have the in-tank pump...you have one or the other unless the PO made up the system. The OE system cannot support two pumps unless the PO has modified the wiring...

Autozone's book is following dodge protocol...they will probably not know what is going on with a diesel (do not rely on them to really know anything about your diesel). I have too often had them trying to sell me gas-engined truck parts for my Cummins...they even had a listing for spark plugs...

If your filter-mounted pump fails, dodge will replace it with an intank pump...but they remove the filter mounted pump. This "update" runs about $600. You can probably buy the filter-mounted pump from Cummins for about $300, if they haven't quite making them (this was the price nearly 3 years ago).

FWIW, the end of the filter-mounted pump was sometime in 04.5...my 04.5 600CTD has the filter-mounted pump, but my neighbors early 05 didn't. They all have a large fuel module that can be mistaken for an intank lift pump...

steved
 
dodgeplowman21 said:
I was standing at the counter and they selected the diesel option. Both one has a 6 in the vin, the other has a C in it. They both say there is a fuel pump in the tank. I got a haynes, I'm gonna check tht out and see what it says.
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The "6" and the "C" are the transmission...one is the auto, the other is the manual IIRC...

steved
 
Ok. That is what I wasn't sure of. I think they were selling their fuel pump for 200 bucks. I just replaced the lift pump on the filter side about 3000 miles ago, with a replacement one I found on ebay. I'm thinking about getting any auxiliary pusher to just help pull fuel from the tank. Also, (stupid question) but what do you mean by PO? Having a brain fart at the moment.
 
I'm thinking about getting any auxiliary pusher to just help pull fuel from the tank.
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I know that if an aux / pusher pump fails on a 2G the vp44 cant pull fuel through a dead pusher pump. ( when between lift pump and it) Is this also true with the CR?
 
HOLYSMOKES said:
I know that if an aux / pusher pump fails on a 2G the vp44 cant pull fuel through a dead pusher pump. ( when between lift pump and it) Is this also true with the CR?
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Duramaxes don't have a LP, GMs penny pinchers strike again. A LP just helps take stress off the CR pump, probably last longer on a Dodge than a Dmax.
 
Couple points...

The CP3 does have an internal lift pump...it will draw fuel past the in-tank pump, but not past a filter-mounted pump. I've read where guys have continued to drive with a bad in-tank pump, but a bad filter-mounted pump just runs out of fuel and you're dead in the water.

I believe the reason the GM version doesn't use a external lift pump is the fact that the CP3 is also mounted lower in relationship to the fuel tank (less head to prime).
 
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