I am new. this is my first post. I posted this on oilburners and have not recieved any feedback yet, probably because of the hoilday weekend. I have an '04 FWD CC 6spd. The dealer recently installed a lift pump in the tank and removed the one from the side of the filter housing. I was able to keep all the old parts. So after a week of running with only the in-tank pump I reinstalled the lift pump on the fiter housing again. I have run it this way for three weeks with no problems. I did this to keep the injection pump supplied with plenty of fuel. Both pumps cycle on and off as if they were the only one installed. The top pump seems to draw fuel through the bottom and vice-versa if I kill power to one of them. Any input or recommendations would be great, I hope this turns into a good modification. No complaints so far. Thanks for any advice.

 

Are you trying to keep the pump cooler with the extra fuel to increase pump life or for perf gains? Or both? Just curious.

 

It looks to me it will be a benefit all the way around. More fuel to lube the pump, if one pump fails the other will keep running, and hopefully I will gain in performance. I hope to install a fuel gauge soon and let everyone know the difference in pressures between the in-tank pump and the filter housing pump. If anyone has pictures for a gauge install please let me know.

 

I am glad you did this, I mentioned it a while back and was told that this set-up wouldn't work because if one pump stopped it would plug the line. I am glad you rpoved them wrong. Now GET A FP gauge and let us know if you are able to keep the F/P up more with both pumps working... If so I am off to get the tank pump installed ....

Are you bombed any??? or all stock???

 

Just getting started. I am out powering the stock clutch now and have the new one sitting in the back seat. Up to now the clutch has slipped with the monitor set to extreme. I updated my signiture so you can see my mods. I am going to post some pictures when I learn how to upload. My camera is six megapixel and I always save in six so I don't know how to modify them to fit on the website.

 

I picked up a banjo bolt for a vp44 pump with a shrader valve to hook up a fuel pressure gauge, now I will be able to see what pressures are making it to the cp3. Is this overkill, having two lift pumps?

 

Having that windshield washer fuel pump inline with the in tank is a waste of time, it WILL fail, fuel is to dry now to lube anything. that in tank is a more efficient pump and your just making it work harder. Plumb in your gauge and monitor your pressure, that'll tell you the overall condition of your fuel system.

 

How did you manage to get the one in the tank replaced if old one on engine was working? Is this something YOU paid for and NOT D.C. warranty?

 

I just tested everything with a brand new "Noshok" 0-30 psi gauge. Here are the results. Some supprised me.


Idle Cruise set@70mph Lowest PSI (under load)
Both Pumps 17 1/2 16 10
Top only 5 4 0
Bottom only 0 0 0

Prior to having the gauge I only started and ran the engine and both seemed to deliver fuel. Little did I know that the top filter housing pump would not allow fuel to pump through it even though the engine would run for 20-30 seconds, I just shut off the motor and thought everything was good. As for the results of the top pump running alone it may be working harder to draft fuel through the in tank pump or it may be getting weak. I was only able to get the top pump pressure down to 0psi with full throttle for more than 20 seconds or so. The pressure would drop to 1psi and only after standing on it for about 20 seconds it would got to 0psi.

This may or may not be a good thing for all but with both pumps running the pressures look good to me and now I have a gauge to monitor them with. Hopefully this will also extend the lives of both pumps and I will continue to get plenty of fuel at a minmum of 10psi.

All the testing was done with both pumps installed. The only thing I did to test each was to disconnect the electrical power supply. All testing was also done with 5" exh. BDDL on Extreme and about 120gals of fuel onboard.

I hope this is good info. for you. PM if you would like my phone number to talk about this.

 

when I saved this info it layed out good however it uploaded all set to the left


--------------------Idle--- Cruise set@70mph----- Lowest PSI (under load)
Both Pumps -------17 1/2-----------16 --------------------10
Top only ------------5 --------------4 ---------------------0
Bottom only ---------0-------------- 0--------------------- 0

 

Sounds like the top pump will pull through the bottom pump, but not the other way around. But if you are getting this kind of pressure with both pumps, it is well worth a try (using both pumps) since it is alot lower cost than the more expensive options out there.

I could be completely wrong, but if you have that kind of volume going through the pumps, I would think that they would last longer just from the cooling process alone.

SO woste case, if the top pump failed on the side of the road. How long would it take to install the bypass set up so you could run just the back pump???

Thanks for the follow up on with this... it is still promising news...

 

Looks to me by those number that not only is the top pump not working but it's also restricting the lower pump. 5 psi at idle does not sound like factory specs for a lift pump on the block. 0 psi with the in-tank pump does not sound possible either. The only number that looks plausible would be when both pumps are activated and the bad upper is allowing the in-tank pump to do what it is designed to do. Just my .02 but if 5 psi @ idle on the lift pump that's probbably why it was changed. Just doesn't sound right.

TRAVIST

 

This is only true if you already have a working second pump. The stock pump on the side of the engine is $399.00 and it’s a star piece, so you just can’t go buy one at the dealer. You have to get it at the Cummins shop. My FASS was not much more than that.

 

Just a heads up here...
And nothing against your idea.

The Cascade valve in these trucks are not the most reliable and neither is the pop off. Many have been proven to be well out of spec.
I learned this through some symptoms I had when running fuel pressures of 14-20 psi at idle. Single pump.
I was supplying too much pressure and much of my fuel was returning to the tank...heated from being pressurized.

I have been running the In Tank replacement now with 7.5 at idle and I cannot pull it down below 4 with the BDDL on Performance or Extreme. My clutch is the Southbend FE.
I am putting a by pass into the supply line to the CP3 to the CP3 return line so that there is always a supply of fuel on demand to the engine.
Thanks to Superduty and his by pass idea as it helped me narrow down a glitch in this truck.
Also, Dodge does not measure psi anymore on any of these trucks to determine if a lift pump has failed. They measure volume over time into a measuring cup. I believe the numbers they are using now are 450ML in 7 seconds when initially they were saying 330ML in ten seconds.

With the by pass change I can see where folks [high powered] thinking the rail is running out of fuel...is not going to happen anymore since nearly 70% of the fuel goes back to the tank...a good amount of it can be caught at the by pass to feed the pump/engine.

Scotty

 

Just fyi. These list pumps are no longer a star part. All of them are being replaced as they go bad with the in tank version so you could not get at the dealer anyway star or not. You are correct with your volume numbers also Scotty.

TRAVIST