Engine/Transmission (1998.5 - 2002) Installed Fuel Pressure Gauge: Now I'm Really Confused

[DocStressor]

After 52K on my transfer pump using just an idiot light to monitor fuel pressure, I installed a Westach gauge. The first thing I noticed is that the pressure would rise to 9 psi when I turned the key and would drop to 0 as soon as the pump shut off. Once the engine was started, the pressure bounced around between 0 and 9 psi until the engine warmed up a bit. Then it would register 9 psi at idle and 6 psi at WOT. On a 300 mile trip this weekend, I realized that the pressure would often drop to 0. Typically when I was drifting down a long grade.



So my questions are:



1) Is this normal? (probably not)



2) Is there an easy way to determine if I have a problem with the pump or the gauge?



Thanks in advance for your help.

Doc

 

[darkhorse]

The numbers are a little low but not uncommon. The one thing that strikes me as strange is the dropping to zero while desending the long grade. You should see a normal idle pressure then. The VP44 will funtion normally down to 5psi under heavy load.

 

[Ereynolds72]

Wow Doc! You have written this almost as if you were reading my mind. I installed my Westach FP gauge yesterday. I used the hose available from Genos so installation was simple. I purged the air too. When I started it I was getting about 9. 5 psi at idle. I went for a spin and it hovered about 6 psi at cruising (45-55mph) and when I got on it the pressure needle actually dropped to zero and 1 psi until I stopped accellerating where it returned back to about 6psi. Fom what I've read so far, these are not normal. I was prompted to start monitoring the fuel pressure when I felt "dead pedal" on a drive back to Indiana a few weeks ago. I was in traffic and kind half way coasting when it happened.



I checked the codes by turning the key on/off/on/off/on and te 0216 code appeared so I took it to the dealer. They checked it out and said they cleared the code (which tripped 50 starts ago) and could not get it to trip the code again or duplicate. They also told me all the pressures were normal and that "they" would not approve the repair under warranty.



Other than the "dead pedal" the truck drives and sounds great so I'm left here with my fingers crossed. I plan to go ahead and get a cummins lift pump and put it on myself but what really ticks me off is the VP44 could go any time and I'll most likely be left holding the bag myself.

 

[PC12Driver]

My last pump was doing something similar. After running with light throttle for a while or coasting to a stop, my fuel pressure would drop to about 4psi. Most of the time I could put a load on the engine and pull the pressure back up, but sometimes I needed to shut down and restart (like Windows) to get the pressure back.



I'm thinking that the pump had worn to the point that high resistance (low fuel demand, high psi's) will cause the pump to stall out (cavitate). And when I increased the flow with the heavy throttle, the fluid would "stick" back to the pump vanes and start pumping again. At least that's how it worked in my mind...



Anyway, replaced the pump and all is better. That was after about 40k miles on the pump.

 

[CSnyder]

I also had this exact same scenario last week but I have had my guage in for quite some time. I called the Dodge dealer and they told me to bring it in for a warranty replacement of the lift pump. They knew what the problem was without diagnosing it and when I got back in town they pulled me in right away and changed out my lift pump with the last of the remaining block mount style pumps. He promised me that later this year when that one fails they will put the tank pump in and I will install a pusher to help the low pressures the in tank pump has. Hope this helps, Chris

 

[johncameron]

My 2nd and 3rd stock pumps died the exact same way as you described. That's why I put a fass on last month.



JC

 

[DocStressor]

Thanks folks. So the consensus seems to be that the pump is going south. I guess I'll just replace the pump and see if the pressure readings stabilize. 52K seems to be longer than most pumps hold up anyway.



Does anyone have any thoughts on the in-tank replacement kits vs the standard Carters? My engine is bone stock. Do you think that the low fuel pressure reported for the tank pumps would still be a problem?

 

[Thomas]

... Does anyone have any thoughts on the in-tank replacement kits vs the standard Carters?...

A failed in-tank pump will probably be harder to change alongside the highway than the OEM pump. On the other hand, maybe it won't need to changed again.

 

[PC12Driver]

... On the other hand, maybe it won't need to be changed again.

Good one! :-laf

 

[jkalchik]

I put a full set of Westach gauges (fuel pressure, oil pressure, combo boost/EGT) on in February. Got anywhere from 0 to 6 psi. When I changed the lift pump, I'm now getting 16+ PSI, occasionally down as far as 12 psi WOT.



Change your LP.

 

[DocStressor]

I was just quoted over $900. 00 for the in-tank retrofit pump setup. Does that sound in line with other dealers or are they trying to gouge me?



In any case, I'm just going to replace the existing lift pump for now.

 

[AKAMAC]

Doc, I just replaced a new LP with my "old" LP that was replaced by another LP. You are in a crap-shoot with the replacement units. My OEM unit I replaced at 83k is still functioning at 10 PSI idle, 6 WOT. I'll post more after I talk to seller. Mike

 

[kkmckinney]

Buy a BD auxiliary lift pump. When your Cummins lift goes out you Westach fuel pressure gauge will tell you when the needle moves and is not pegged at 15psi. I replaced my Cummins lift pump and now the needle is again pegged at 15psi. The Cummins lift pump costs $140 and can be installed in one hour.

KEN

 

[Steve Campbell]

I assume everyone here has checked the "cleanliness" of their fuel filters. (I probably should not have said that!)



I have had the fuel tanks out of three different 24 valvers to clean the "crud" that was blocking the fuel pickup (intermittently) and causing the same sorts of fuel pressure variations that have been described here. On my own truck, I "defeated" the fuel pickup blues by removing the "screen" (more like a membrane material) from the in tank fuel pickup assembly, and mounting a "prefilter" on the frame up stream of my frame mounted lift pump. That was two years ago, and I have not had to change the fuel filter on the engine since (I did change the "pre" three or four times in that stretch).

 

[Ereynolds72]

As I mentioned above, I was getting about 9. 5psi at idle and as little as 0-1psi at WOT. I bought a cummins replacement pump yesterday and put it on last night. FP jumped right up to 15psi +. (only have a 15psi gauge)



That was the first lift pump at 92,500 miles. I'm glad i got the FP gauge... I have TDR to thank for that.

 

[.44 mag]

I just got a tank mounted replacement pump put in under warranty along with a new VP44. I installed an Autometer 0-15 gauge to read pressures. My pressure at idle is a steady 12psi. As I drive with light throttle about 1800-2200rpm pressure ranges between 8-10psi. Wide open throtttle pulls the pressure down to about 5-6psi. I'm tapped in to the port on the VP44 with the flex hose from Geno's.



I never had a gauge on the old lift pump. Do those numbers sound in range??





Thanks!

 

[BigMike]

Mine did exactly the same thing after I installed a guage. Wasn't the guage that was haywire. It was telling me my lift pump was shot. Replaced it at 80k miles. Runs at 15psi at idle and never less than 9psi while running. Cruises at 11-12psi. Now have 115k miles on my truck. Not sure why a person wouldn't put a guage on. Otherwise, you're driving blind and won't know you have a problem until the VP44 dies. I understand that's about a $2000 fix.

 

[DocStressor]

Put a lift pump in yesterday and I now have the same fuel pressure readings that BigMike reported above!

I am a now a happy camper. I've noticed an increase in smoothness and engine power. I just saved my VP44!



Thanks much to everyone who replied.



Two points:



1) Nobody should run on of these trucks without a fuel pressure gauge.



2) Believe the gauge!