Engine/Transmission (1998.5 - 2002) Lift Pump cruise pressures?

[NVR FNSH]

I just drove 900 miles this weekend - SF-LA roundtrip - with Briar Hopper's fuel pressure gauge taped to my windshield. I was reading the pressure at the inlet to the VP44 (post fuel filter). Fuel filter is new.



At 2000 RPM/65mph cruise I get 7psi fuel pressure

At 2500 RPM/80mph cruise I get 5psi fuel pressure

At idle/no load I get 10psi fuel pressure

Pre-fuel filter I get 11-12psi fuel pressure so it looks like it meets the manuals 10psi requirement - barely.



Here's my problem: A couple of times in the last two weeks my accelerator has gone dead - happens in 5th or 6th gear. RPM will slowly increase if I'm on level ground but it feels like there is no boost happening. I tried stomping the throtttle several times and that didn't do anything. The only code I get is P 1693. I have disconnected my VA CPC and the same problem/symptoms occur. Am I experiencing a lift pump death rattle or is it a TPS/APPS issue? Truck just turned 60K so it's under warranty but getting to the dealer is a PITA at this time so I'd like to 'help' him trouble shoot the problem.



Thanks in advance,

Brian

 

[klaybus]

Gauge readings

Seem LOW to me! Not sure on the code but anything below 7 PSI is bad! At idle I have 14 PSI, cruising I have 12-13, & under WOT the lowest I can get is 10-11 PSI.

The dead throttle your experiencing sounds like the APPS. (Accelerator Pedal Position Sensor) I believe the procedure for resetting this is to un-hook batts for 30 minutes, reconnect, & slowly depress go pedal to floor board..... Twice.

If I'm wrong I'm sure someone will chime in & correct me.



Clay

 

[CFAR]

https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=80561



You might want to read this thread, some people experiencing the same symptoms as you have found it to be the Inj Pump.



As far as the lp pressures go, they are too low. Whats your WOT #? How low will it go???????

 

[rweis]

Unloaded



wot ~ 12



pulling 8k RV



wot ~ 11



Bob Weis

 

[RustyJC]

Pre-filter pressures on original lift pump, 15,500 miles, towing 36' 13,500 lb 5th wheel RV last weekend:



Idle - 16+ PSIG



70 MPH Cruise - 15 PSIG



WOT - 13 PSIG



Rusty

 

[NVR FNSH]

WOT fuel pressure will drop to 1-2psi measured at the injection pump. Is there an updated test procedure that specifies a WOT fuel pressure requirement? Based on my '00 service manual my lift pump is good... ... .



Brian

 

[Thomas]

TSB 14-002-03 is the latest D/C transfer pump diagnostic standard that I'm aware of. It makes it a bit more difficult for the customer to know for sure, now that we've purchased fuel pressure gauges, that the transfer pump is out of spec (perhaps the reason for the TSB



Prior to this TSB, but after the info in the model year 2000 Service Manual, there was talk about a standard of "never below 10 psi (or was it 8 psi?), this information available when a Dodge service department called the D/C STAR line.

 

[jmadden]

Here's some feedback I got from Cummins...



"On ISB engines, the lift pump does not start operating with the key switch on until the engine is bump cranked. Then it starts working for 30 seconds and then shuts down by itself. During 30 seconds of running, it primes the fuel system. Pressure during this running period should be around 13 to 15psi and during cranking, the pressure should not drop down more than 8psi. We have seen in the past that even if the pressure are found to be within specs, priming pumps due to internal check valve and excessively worn out pump impellers, that it creates fuel spikes which create and pump air into the fuel system, which leads to the major problem in the VP44. There is no fool proof methods to check the internal condition of the priming pump or to check air created by the priming pump. "



jm