Gil2264

I just finished my little test. BTW, the return line is rubber down at the front of the frame rail. It allows for flexibility between the engine and rail. The bad news is, it does appear to be the pump bypass sticking open. Clamped off the return, bumped the starter, 17 psi for about 5 sec, then sudden drop to 7 psi with an increase in pump speed. I wonder how hard it'd be to disassemble the pump and try cleaning that bypass.

This is THE topic have been looking for for over a year. If I understand what you are saying..."increasing the inlet fuel pressure ,will not help hold open the overflow valve, thus allowing more fuel to flow through and cool the pump. Now...Here is my question, If the overflow valve is sticking open, will it cause a decrease in the measured pressure at the inlet banjo bolt. I ask this because I have been having problems with sudden drops in LP fuel pressure when there is little or no throttle applied. Example: I'm driving along either towing something or climbing a small grade, fuel pressure generally hovers around 14 psi, as I come to a stop light or sign and decrease throttle, my LP climbs to about 17 psi for a second or 2, then suddenly drops to 3-5 psi, as I accelerate away, my LP pressure drops to almost 0, then suddenly jumps to 11 or higher depending on how hard I'm into the throttle. As I approach cruising speed and decrease throttle, my LP begins climbing to 17 psi again, then suddenly drops to 5 psi until I romp on the throttle for a few seconds. I have been suspecting the Overflow Valve for some time, but have had a hard time getting answers. If I may interject one observation to your scenario MoparMan, as to the pump getting no cooloing/Lubricating fuel flow during long coast/decents. Just tonight I read a post somewhere else that claimed that the overflow valve had a small bypass port (always open) to make sure there is always some fuel flowing through the pump and back to the tank thus insuring a constant supply of cool fuel flowing through the pump. Other posts I've found on this topic tonight: Read Post #5 - http://www.cumminsforum.com/forum/98-5-02-powertrain/234058-funky-fuel-pressure-overflow-valve.html http://www.blacksmokin.com/98-5-02-cummins-isb OOps fire call...gotta run... ---------- Post added at 06:12 AM ---------- Previous post was at 04:02 AM ---------- Just found another possability as to why my fuel pressures keep dropping...Nothing's simple!!! I stole this from http://www.dieseltruckresource.com/dev/fuel-pressures-and-flows-lift-pump-etc-t138789p2.html Post # 30 I revived this thread because my friend's newly acquired '02 HO truck's lift pump died the other day in a bad part of town. I went to rescue him with a new NAPA pump I had purchased as a spare days after I bought my own truck. This left me with no spare pump, and also motivated me to get my Walbro system installed that has been sitting in a box. I disassembled the failed Carter from the '02 to determine why it failed. I was rather astonished to see that it looked brand new inside (unknown mileage) and the vanes looked perfect. The plastic drive slot was also intact and the motor was working (we could obviously hear it running) but got no fuel through an open fuel filter top. Swapped pumps after I installed a new filter element and he was good to go. What happened was the pump's internal bypass check valve died and caused the pump to suck from the internal cavity vs the inlet because is was the path of least resistance. It appears like the OEM Carter installation in the CTDs is bypassing (or recirculating) A LOT of fuel within the pump when the engine is at idle. When the fuel pressure drops below the bypass threshold (15 psi?), the bypass shuts off and delivers enough volume to the VP44 to keep the LP from recirculating it's own fuel--which heats and aerates it. This makes me think that simply idling the engine does the most damage to the LP and possibly the VP44 by shoving all that aerated fuel into the fuel filter. I am not sure if the filter can remove all the aeration, but I doubt it. Relocating the Carter down next to the fuel tank helps a bunch with cavitation, but the pump will still bypass internally when the engine is not consuming much fuel. The Dodge fix of the intank pumps help, but they are still problematic from what I have read here and elsewhere. It appears like the best set-ups (LP) are the ones that aerate or heat the fuel the least amount possible. Walbro or other high flow pumps (insert favorite LP here) with an external pressure regulator located at the VP44 inlet, set-up to dump excess fuel back to the tank (not into the inlet of the pump!) seems like the easiest route to gaining a constant 13.5 psi of fuel supplied to the VP44 under all conditions, but they do recirculate a bunch of fuel. The RASP pump or other mechanical pump (I'm not picking on RASP here--just an example) is closer to providing variable fueling based on engine RPM, but as HOHN pointed out, a Cummins will use FAR LESS fuel at 2,000 RPM while in neutral vs 2,000 RPM under a heavy load, but the RASP will provide exactly the same volume in either case because it is RPM dependent. The system Bent_Valves has looks like the ultimate set-up. Run the Walbro (or other LP) with a PWM regulator and feed the engine exactly what it needs when it needs it. The bypass would be there incase of PWM failure. It would not use it otherwise as most systems (internal or external bypass) need to do. Now if there was only a ready made PWM kit with a harness to connect the LP and a pressure transducer, we would be set! ---------- Post added at 06:31 AM ---------- Previous post was at 06:12 AM ---------- Actually it may not be so hard to test both the Overflow Valve and the Lift Pump's internal bypass. At present, If I bump the starter, my Lift Pump Pressure (LPP) goes up to 17 psi, then drops to 3-5 psi. THE TEST... If I clamp off the return line, and the LP is operating correctly and the problem is in the Overflow Valve the LPP should stay at about 17 psi. If I clamp off the return line, and the Overflow Valve is operating correctly and the problem is in Lift Pump's internal Bypass then the LPP should do as it's doing now, climb to 17, then drop to 3-5 when the Internal bypass opens and sticks. I'll have to try this later as its 0230 here...

Sorry, Newbie here. Unfortunately, as a farmer, I have very limited play money, I can't afford a $4-600 programmer, however I was recently able to swing a Diablo Sport Power-Puck. Everything I've read suggested that it is the best bang for the buck. As advertised, it made a definite improvement, but there is still a definite turbo lag. I know, that's the nature of the beast. I was wondering what effect a boost fooler and/or Boost elbow would have combined with the power puck. Does the Puck already do boost fooling, or would it help or hinder. Also where would the fooler go, between the MAPP sensor and the Puck, or between the Puck and the stock harness? Any help would be appreciated.

I just recently installed a power puck on my 2001 Ram...WOW!! what a difference! Frankly its all I need, or can afford. I have however been looking at a lot of posts about smoke switches. There seem to be two different wiring diagrams, One simply jumpers (through a SPST switch) the +5v. to the signal wire, the other seems to say that you need to bypass the fueler box (Edge, Quadzilla...). Does the Power puck qualify as a fueler box, or is more of a glorified boost fooler, and does it need to be bypassed? I've also seen some posts suggesting you wire a 10 ohm, 10 watt, resistor into the jumper wire/switch. has anyone considered installing a rheostat in place of the resistor, thus giving the ability to tune the amount of boost shown? I appreciate any input, thanks.Dan

I went with Moog. The cheapest price I found was at Amazon.com, but it was hard to determine which ones I needed from their website. Go to an autoparts website to find the right ones then write down the part # to find them on Amazon. Also, If you have a 2001 model with a Dana 60 front axel, don't even bother starting the job before you get the right balljoint puller. All 4 of my joints were a bi###, to get off, even with the right puller.