MPG=lift pump (Long sorry)

[N Balsden]

Hi this is my first post here,I have a 2004. 5 auto,4. 10 gears. pyro,boost,transmission temp,fuel press gauge. and MBRP duel exhaust. This truck has never been chipped. It has 33000/km on it



I have had my truck in for low fuel pressure, poor mpg, a slight surging problem and noise from an injector. since the 3rd week I got it. I got the truck and was getting 13. 5 mpg and it has only gotten worse to a low of 7. 08 mpg. 321/km to a 128L tank was the worst . It has been reflashed 3 times not including the reflash for the white smoke. Each time it only brought it up to 13. 5mpg max hand calc and 15mpg highway. My average mpg seems to be about 10 to 11 450km per tank. All of this on an empty truck I wont get in to towing.



Now for the fuel pressure. Running PSI the truck sat at about 4,driving it moved from 2-5,and WOT it was 1-2, towing it was at 0-3. towing a hill it sat at 0 the hole time. Dodge said every time I took it in "the truck was within spec. . "



Well Christmas morning rolls around and were on the way to the inlaws and the truck just up and dies. lift pump is gone. 4 hours on the side of the highway later we get towed. Tuesday moring call dodge and tear a stip off them after they tell me they cant get the truck in till friday. Well they get it in that day and by lunch they call back and tell me my lift pump is gone. I said I know that,they say It will be replaced under warranty but I have to pay for another fuel filter. I had replaced it twice already by this point on previous trips to the dealership.

Get the truck back on thursday start it up,well it sounds different and its not surging anymore. when I say surging I mean in drive at a stop and on the break you cant really see it on the rpm gauge but you can hear the motor reving up and down verified by dodge. Well i go to leave and the truck feels like it has way,way,way more power I now really like to drive my truck. I go fill it up look up at the over head and its now reading 19. 1 fast city driving at this point it has never been over 13. 5 in the city. well we leave to go return a superduty that I borrowed from the in laws. On the highway the overhead is reading 21. 3mpg at 100km/h its was about 150km round trip and the over head stayed above 20mpg the hole time. the truck is now staying at around 19mpg/city I have just over 600 km on this tank and I have just under Half a tank left. I will hand calculate it when I fill up next.

This is my first diesel,I am reading all I can about the dodge diesel. I don't really understand how the lift pump can make that much of a difference. I guess my question is. Is this normal. Can a lift pump make that much of a difference to the over all performance of the truck.

Thanks for reading . At long last very happy with my truck...

 

[McLaughlin]

I don't own a 3rd gen but it sounds like the dealer was stringing you along until the truck was out of warrenty. If your lift pump had continued to work at those pressures, I suspect your injector pump would have failed eventually and if it was out of warrenty it would have cost a bunch to fix. Apparently, the 24v injector pump is pretty dependent on the fuel pressure from the lift pump for cooling so with low fuel pressures the injector pump doesn't get cooled as it should. I'm sure someone else on the forum can provide what the "normal" values are for fuel pressure but I think for my truck the "nominal" pressure is 25 psi.



I'm not sure of the real mechanics of the fuel system as it relates to fuel economy but everything I've been told and read is that yes, low fuel pressure will reduce the fuel economy. It will definetly affect performance because without enough fuel pressure the injector pump can't effectively operate the injectors and so you loose power.

 

[betterthanstock]

spec. . "



Can a lift pump make that much of a difference to the over all performance of the truck... .

Welcome to TDR.



If the injection pump is starving, you get low pressure, which brings with it poor atomization and late injection because it has to stay open longer to inject the same quantity of fuel to make it run.



Others with similar symptoms, print this out and take it to your dealer.

 

[RMarkey]

would putting one of the afermarket fuel pumps/filter systems on remedy that sort of thing? What was it, the FASS or similar systems, that provide better filteration and actually change the pump system. I haven't looked into it myself yet, I figured my current setup shouldn't starve for fuel, yet. I may be wrong but just figured I'd ask, maybe it'll help out.

 

[nick05]

rmarkey, i would definently get a fuel gauge if not already, and it wouldn't hurt to put on another pump as have i on my 05. installed holley blue after i saw my gauge at 2-3psi, after the blue 14-15psi constantly with the quad box on 60 & 100hp settings. can't even lower the psi's down at WOT.

 

[TowPro]

anybody had there warrante voided for adding an additional lift pump?



I tried to put one on my 98 but they kept leaking so I went back to the factory lift pump

 

[McLaughlin]

would putting one of the afermarket fuel pumps/filter systems on remedy that sort of thing? What was it, the FASS or similar systems, that provide better filteration and actually change the pump system. I haven't looked into it myself yet, I figured my current setup shouldn't starve for fuel, yet. I may be wrong but just figured I'd ask, maybe it'll help out.

Supposed to. Two systems I've seen are FASS and RASP but I don't have experience with either one. Before I replaced the fuel pump though, I'd put in a fuel pressure gauge and verify I had a problem(although they probably wouldn't hurt anyhow).

 

[n7gxz]

I don't own a 3rd gen but it sounds like the dealer was stringing you along until the truck was out of warrenty. If your lift pump had continued to work at those pressures, I suspect your injector pump would have failed eventually and if it was out of warrenty it would have cost a bunch to fix. Apparently, the 24v injector pump is pretty dependent on the fuel pressure from the lift pump for cooling so with low fuel pressures the injector pump doesn't get cooled as it should. I'm sure someone else on the forum can provide what the "normal" values are for fuel pressure but I think for my truck the "nominal" pressure is 25 psi.



I'm not sure of the real mechanics of the fuel system as it relates to fuel economy but everything I've been told and read is that yes, low fuel pressure will reduce the fuel economy. It will definetly affect performance because without enough fuel pressure the injector pump can't effectively operate the injectors and so you loose power.

McLaughlin,



Just an FYI for you, the 3rd gens do not have the same type of an injection system that the 24v 2nd gens do. The 3rd gens have a high pressure fuel pump (CP3) that feeds a common rail (manifold) that distributes the high pressure fuel to the injectors which in turn are fired by the computer, the CP3 does not fire the injectors like the VP44 does on the 2nd gens. The VP44 is the one that is sensitive to the lack of fuel. The CP3 I believe is like a high pressure hydraulic gear pump.



Kevin

 

[N Balsden]

Update:

Just filled up the truck 100L and went 669km works out to 18. 93mpg city(only 150km was highway). my overhead stayed at around 17. 5 for the last half of the tank down from the 19-19. 1 it read for the first half. I was driving harder then I normally do for the last half. I am happy with the results and it looks as if all the problem I have had since the truck was new are now gone. The fuel pressure now sits at 8. 5-9psi running and 7. 5-8. 5 driving. It will not go below 7. 5 even WOT.

 

[nick05]

glad to here the fix. what did you end up doing?

 

[OHale]

Update:

... The fuel pressure now sits at 8. 5-9psi running and 7. 5-8. 5 driving. It will not go below 7. 5 even WOT.

Well, it should have been clear to your dealer that your lift pump was dying. Normally that is the best way to have it go, giving you a chance to complete a trip and get to the dealer for a repair. IMO they let you (for whatever reason) keep running until you were stuck by the side of the road. Some of our members aren't exactly young (myself included) and being stuck in the dead of winter in the mountains isn't my idea of fun.



I bought a spare LP and keep it in the truck. The canister mounted LP can be changed out as a road-side repair. I am assuming they repaired your truck with a tank mounted pump. I haven't been hearing about many failures with that set up.



Glad your truck is running as it should be! Personally, I would find another dealer in your area to go to.

 

[Disel Dave]

where to check fuel pressure

Update:

The fuel pressure now sits at 8. 5-9psi running and 7. 5-8. 5 driving. It will not go below 7. 5 even WOT.

Where Did you get this Reading from? Is there a test port to check pressure Between the lift and the CP3? Or do you have to make someting up to do it? I would think that is where you got this reading from Im sure the Rail pressure is high. Does any one know where I can get a Cut view of a 325-600 with a listing of what each senser is? I been in powerJoke land for years and it is time i know what makes a CTD tick.

Dave