After watching the last two pumps go out even faster than the first three I'm convinced that moving the pump near the tank made the problem (which noone can accurately diagnose) even worse. I believe the problem is electrical and that the longer run of power cable with the relocation kit has compounded the problem and is killing LPs faster. I've had a couple of our heavy equipement mechanics ride with me to watch what the pressure does when the pump goes bad and they agree.

If the problem was mechanical (bad impeller, clog, etc.) why when the pressure suddenly drops can I cycle the key off and on instantaniously (without even taking my foot off the clutch and basically keeping the truck running) and the pump "resets" and goes back to normal pressure? The problem has to be improper voltage going to the pump. Does anyone know what voltage the pump should see? If it's 12V I believe what I will do is use a relay to give the pump 12V straight from the battery and see if that improves things.

 

I'll check mine with my meter this afternoon when I get home and post.

 

I dropped the tank today. I found a little trash in the tank and a couple spots of water floating around on the bottom but nothing I wasn't expecting. I did do some inspecting of the pickup system and think I found at least part of the problem. The pickup sucks fuel through two layers of a very fine screen seperated by a spring ultimately connecting to a small rubber diaphram. The diaphram on mine seemed very difficult to move if not stuck. What I did was cut out the upper layer of screen containing the diapram out removing the restriction. I'm going to install an in-line, servicable, filter on the fram just before the pump. I also found a dryrotted cap covering a port on the pickup assembly as well as a rollover valve with no hose at all connected. I fixed all that and cleaned the tank out and filled the tank back up. I've only been on a short test drive but so far things seem fixed. The pump seems louder as if it's spinning free now. The pressure is around 12 psi still and it pulls down to around 6 psi at WOT but this pumps is definitely worn. The one side affect I am noticing so far is that it takes about 3-4 seconds for the fuel pressure to bleed off according to the gauge where before it dropped instatly when I shut the truck off. Any ideas here? Hopefully my lift pump woes are almost over. I still plan on checking the voltage and installing a relay if I think its needed.

 

Sorry for being late Wes,
I got 11.17 volts on the starter bump and 12.82 volts at first idle this morning. My wires are soldered to the original wires.

 

Might want to check the Amps...this is what really kills the motors. High resistance in the lines will cause amps to jump causing brush ware. Voltage around 11V shouldn't be that big of a deal (Other than your alt is not working correctly!!!!). If you got a good connection, the amperage will actually drop with voltage. (At least it does on our test bench when i turn down the voltage) NOW i dont know what the ideal amperage the stock LP should be seeing. BUT this is why we went to a relay harness for the FASS to help with premature brush ware.

 

Thanks for the info. The 11.17 volt reading was starter bump, engine not running.

 

Replace the stock fuel module thats in your tank now.Its restrictive and it tends to erate the fuel.Mopar has a redesigned fuel module with a pump in the tank.Its good for about 8to 12psi by itself.If you gang it up with a second lift pump you get 25psi or more at idle you probably wont be able to pull it down below 20 psi at WOT.

 

I don't know a lot about fuel pressure except what I've read here on TDR; heck I don't even have an FP guage on my truck yet.... but I have read that if you have TOO MUCH pressure you can have problems starting.

Read This topic

FWIW

 

where can you buy for 380.00 ??

 

At the time he posted that, you could find the HPFP at that cost. BUT due to metal costs going though the roof, we had to do a price increase April 1st. I got a brake down of MSRP prices on my site. Most dealers should be around the prices on our site.

 

To anybody that is having lift pump problems, I say get a FASS System. I got one installed on my truck thursday and I love it. Can't pull it below 15 psi WOT. Check that you are getting the proper voltage to the pump, and install a FASS. All of your lift pump problems will go away and you will be doing your injection pump a favor. The way I see it, I would rather spend $600 on a FASS than spend $1200 on a VP44.

 

Wes, I hope this will fix your problem, it did for me.

I was having the exact same problem. I changed lift pumps, replaced the tank fuel module, etc., but kept having the same problem. After talking with a guru diesel tech, he told me to replace the check valve at the VP ... that's the banjo that's on the return line, part number 3941156 ($25). I've been running it for a week and have not had one problem, in fact, my fuel pressure is better than it's ever been ... and more consistent too!

I sincerely hope this helps cause I know what a headache this causes. I'm betting this is the cause of a lot of suspected LP failures/replacements.

 

This is a little bit of a reach, but on a trip 3 years ago, I had exactly the same symptoms on my '02. I started getting fluctuating fuel pressure readings in Georgia. Replaced the lift pump on warranty in Alabama, then it quit again in Carlsbad, NM. Replaced on warranty in El Paso, TX and it quit on me almost in my driveway in Palm Springs. Local dealer's mechanic found a wire broken inside the insulation right at the plug where it goes into the pump. Broken ends were touching.....I was getting fluctuating readings on the fuel pressure gauge......when the wires lost contact, I stopped. He wired in a new plug and I haven't had a problem since - about 40 or 50,000 miles later. It's worth a look.

Lar.

 

So far my problem seems to be fixed. Granted I've only put about 600 miles on it since dropping the tank but so far so good. A pump I was convinced was beyond on its last leg has been operating flawlessly since I dropped the tank and gutted the pick-up screen.

After seeing the design of the intake in the tank itself I'm convinced that's the reason 90% of the LPs that go bad do so. Now I see why Dodges fix was an in-tank pump, so they could replace the pick-up at the same time. I can't believe it's suggested so rarely. I could be wrong but it makes sense to me. I've told all my friends with 24-valves the next time thier LP acts up to drop the tank and fix the problem for good.

 

I dropped the tank and replaced the entire module with the updated all-nylon module. It has a larger pick-up, but had the same style pick-up screen ... this did not help at all! I needed to replace the module, since the original was rusted out. If you've done away with the screen, I hope you've added an inline filter.

As for the info. I got from the diesel guru: he told me that the system should see around 14 psi at the VP (if you're lucky!), no less than 10. The check valve is to regulate the pressure and will rarely allow you to see higher pressures. So it would make sense that if you're throwing higher pressures at it that the check valve would be constantly open and weakening the spring, JMO.