Engine/Transmission (1998.5 - 2002) FASS DDRP Failure?

[Shelby Griggs]

After many OEM lift pumps I replaced the LP with a DDRP in December, already had the Vulcan big line kit and the pump on the frame rail.



Been working fairly good, but I would see intermittent spikes below 10 PSI occasionally, yesterday pulling a decent grade in the mountains I got a low pressure indication and was even pulling a vacuum (negative pressure). I have a digital SPA gauge that I hope is reporting pressure correctly. I geared down and backed off the throttle, but the pressure stayed low. Once I got to the top of the grade and started on the downhill side, the pressure came up some and just as I was getting ready to stop the truck, the pressure came back full to 14+ PSI and stayed there the next 30 miles or so until I got home.



I have seen 4 or 5 OEM pumps fail in the same manner. Very disappointing!



Like I mentioned, ALL of the lines forward of the fuel tank have been replaced with the Vulcan big line kit, the pump is on the frame, etc. Other than the fuel pickup and the OEM filter ALL components of the fuel system have been replaced. The truck is stock and I was only loaded about 8500 yesterday, not towing, but it sure acted like I was demanding more fuel from the DDRP than it could provide???? Fuel tank was 2/3 to 3/4 full, shouldn't have been sucking air. I didn't notice any loss of power or any other performance issue, just no fuel pressure indicated.



I am not sure what to do next, replace the DDRP (only has a couple of thousand miles on it), add a draw straw or maybe hope this was a one time anomaly?



SHG

 

[ILIANBG]

Mine was doing the same thing, until I dropped the tank, and cleaned up the mess in there. The problem with mine was the bottom of the stock assembly in the tank-the fine mesh screen, which was awful looking (all clogged up). Once I had it removed, everything cleaned up, draw straw installed, it worked perfectly, not even one issue.
So, this was my experience, it does not have to be your case exactly, but sure is worth checking. I do not think it is the pump.
Ilian

 

[LowFly]

After many OEM lift pumps I replaced the LP with a DDRP in December, already had the Vulcan big line kit and the pump on the frame rail.



Been working fairly good, but I would see intermittent spikes below 10 PSI occasionally, yesterday pulling a decent grade in the mountains I got a low pressure indication and was even pulling a vacuum (negative pressure). I have a digital SPA gauge that I hope is reporting pressure correctly. I geared down and backed off the throttle, but the pressure stayed low. Once I got to the top of the grade and started on the downhill side, the pressure came up some and just as I was getting ready to stop the truck, the pressure came back full to 14+ PSI and stayed there the next 30 miles or so until I got home.



I have seen 4 or 5 OEM pumps fail in the same manner. Very disappointing!



Like I mentioned, ALL of the lines forward of the fuel tank have been replaced with the Vulcan big line kit, the pump is on the frame, etc. Other than the fuel pickup and the OEM filter ALL components of the fuel system have been replaced. The truck is stock and I was only loaded about 8500 yesterday, not towing, but it sure acted like I was demanding more fuel from the DDRP than it could provide???? Fuel tank was 2/3 to 3/4 full, shouldn't have been sucking air. I didn't notice any loss of power or any other performance issue, just no fuel pressure indicated.



I am not sure what to do next, replace the DDRP (only has a couple of thousand miles on it), add a draw straw or maybe hope this was a one time anomaly?



SHG

OK..... few things... ... DDRP's put in place of lift pumps that have had line issues are doomed the same fate. Dare i even say that some good stock Carter pumps are replaced just because they have a bum rap? Rather than feed this "If you got low pressure replace the pump" mantra... . I might like to explore as to maybe why you are seeing low pressure issues with multiple pump’s.



First off we need to make sure that your gauge is reading correctly... especally if you have seen other pumps die like this with this gauge. I want to make 100% sure we have a good measuring tool to use here.



On the inlet of our pump in the banjo, there should be a 144um wire mesh screen. Once you get a base line pressure reading under load and such, pull the screen and see what it does with out it. Might be clogged or dirty. Clean when you got out. Or might consider installing a NAPA 3270 inline between the tank and the pump.



ALSO see what it does at idle with just flooring the throttle to red line. See if the pressure drops down a good amt. If it does, pull the quick disconnect off at the inlet and hose clamp a line to the feed line to the DDRP. Then get a small container of fuel and run the truck off of it. Repeat test and see how it does.



We have seen several issues with stock sending units cause restriction probs and cause the DDRP to drop in pressure. I want to cover all our bases before we condemn the pump.



We have seen where a line kit from the tank (With suciton tube kit) to the DDRP have solved several pressure isssues... . and i would almost bet would save a few stockers as well... ...

 

[Shelby Griggs]

Dan,



Thanks for the tips. I have talked to Eric at Vulcan and am going to visit their shop soon, possibly tomorrow to check some of the very things you mention, they are about a 3 hour drive from me and it is time to get some independent verification of the problem. I do know that most, if NOT ALL of the OEM Carter pumps were dead, those make enough noise, especially when mounted under the cab that the lack of pressure could audibly confirm the problem to be the pump because they quit making noise! I can't hear the DDRP because it is too quite, so I am not getting that audio feedback. One of the OEM pumps was replaced by a Cummins technician who did verify that my diagnosis was correct, this AFTER I changed the FP sensor in a parking lot because I too couldn't believe a less than 12 month old Carter pump was toast already.



The problem seems to be intermittent too, making troubleshooting a bit time consuming, last week (after this initial post) I went on a 60 mile RT, the out leg I could get the pressure to drop at will be standing on the throttle, the return leg not at all. I am wondering if the pressure drop is only occurring in the first 30 miles of operation or so? Come to think of it, in January I took a trip where it was about 19°F when I left the house, real low pressure until about an hour into the trip when everything seemed to go to normal. I have been running commercial B5 for most fill ups when home, since the pump is less than a mile away a the CFN card lock, but I wouldn't think B5 would kill the pump.



At this time neither the local Dodge dealer nor Vulcan think it is in the tank pickup, however that and the OEM filter housing are the ONLY components that haven't been replaced.



Hopefully my visit to Vulcan will find the problem.



SHG

 

[LowFly]

... ... something we ran into today... ... pull that screen that is in the banjo bolt and see if there is debris in there. Clean and reinstall. We had one that had 4 perfect circles in the screen where crap clogged it up. Issue was the same as you were seeing.....

 

[EForbes]

Hello, i put my DDRP on a few weeks ago, and i too noticed that when i first start truck and drive about 70 miles each way to work, the pressure is not consistent for about 10 miles, then it seems that i cant get it to go below 10 psi no matter what. I have vulcan big line from filter to vp pump. I have changed the fuel filter, but its always the same, during the first 10 miles of running each day, it struggles to stay above 10psi, and any throttle causes it to drop to five psi, but after that it pops up and is consistant no matter how long i drive. The other day driving down the altamont pass, it even reached 18 psi. So i have the same question, is there something in my tank floating around, or does the pump need to warm up?
Mine is mounted in stock location, with screen in banjo bolt on inlet.
Thanks for any help provided.

 

[Shelby Griggs]

Update. I visited Vulcan yesterday, we added a temporary mechanical FP gauge, the pump seems to be working, never see less than about 9 PSI at the filter inlet, my permanent electronic gauge is mounted at the VP44 inlet.



The electronic gauge just seems way more sensitive than the mechanical, can trip the the low pressure LED when set at 2 PSI ALL the time. Most of the time the two gauges read with 1-2 PSI in level cruise at highway speeds.



I did notice this morning for the first hour or so that the mechanical gauge was steadily reading lower than this afternoon, around 9 PSI cold and 12-13 PSI warm, it does seem that there is some correlation between temperature and the DDRP output pressure.



Dan, I have a question on that screen, if you don't have any banjos at the input, is that still something I should put in the line? I put that screen in, BUT it seems to me the fuel can just flow through the center AND it is just kind of floating in the line. I have AN fittings with a straight shot into the bump inlet with 3/8" hose. I can pull that screen out and look, it just wasn't clear when I installed how that was supposed to work, even if I had the banjo still in the system.



While there does seem to be some variation with temperature with my installation, I believe the real problem with my setup is in the electronic FP system, so am starting with a new sensor which should be here on Tuesday and then go from there, but I am pretty convinced after driving over two hundred miles with the mechanical gauge that the DDRP itself isn't dropping to zero PSI.



SHG

 

[LowFly]

Hello, i put my DDRP on a few weeks ago, and i too noticed that when i first start truck and drive about 70 miles each way to work, the pressure is not consistent for about 10 miles, then it seems that i cant get it to go below 10 psi no matter what. I have vulcan big line from filter to vp pump. I have changed the fuel filter, but its always the same, during the first 10 miles of running each day, it struggles to stay above 10psi, and any throttle causes it to drop to five psi, but after that it pops up and is consistant no matter how long i drive. The other day driving down the altamont pass, it even reached 18 psi. So i have the same question, is there something in my tank floating around, or does the pump need to warm up?

Mine is mounted in stock location, with screen in banjo bolt on inlet.

Thanks for any help provided.

YOu might pull that inline screen out and clean it and see if that makes any differance. I cant say if you have any debris in your tank or not..... i can say its not an uncommon issue we have seen.

Update. I visited Vulcan yesterday, we added a temporary mechanical FP gauge, the pump seems to be working, never see less than about 9 PSI at the filter inlet, my permanent electronic gauge is mounted at the VP44 inlet.



The electronic gauge just seems way more sensitive than the mechanical, can trip the the low pressure LED when set at 2 PSI ALL the time. Most of the time the two gauges read with 1-2 PSI in level cruise at highway speeds.



I did notice this morning for the first hour or so that the mechanical gauge was steadily reading lower than this afternoon, around 9 PSI cold and 12-13 PSI warm, it does seem that there is some correlation between temperature and the DDRP output pressure.



Dan, I have a question on that screen, if you don't have any banjos at the input, is that still something I should put in the line? I put that screen in, BUT it seems to me the fuel can just flow through the center AND it is just kind of floating in the line. I have AN fittings with a straight shot into the bump inlet with 3/8" hose. I can pull that screen out and look, it just wasn't clear when I installed how that was supposed to work, even if I had the banjo still in the system.



While there does seem to be some variation with temperature with my installation, I believe the real problem with my setup is in the electronic FP system, so am starting with a new sensor which should be here on Tuesday and then go from there, but I am pretty convinced after driving over two hundred miles with the mechanical gauge that the DDRP itself isn't dropping to zero PSI.



SHG

Vulcan has an inline strainer you can run or just go to NAPA and get a 3270 inline strainer. Works with 3/8"s line... . make sure its on the inlet side of our pump... .

 

[KLauber]

How important is it to have any kind of pre-filtration for any Fass pump? I am having the same problem, and changing the filters doesnt fix it either.



Will

 

[DEWright]

Same issue here that you and Griggs are experiencing. I have basically the same set up that you have, new 3/8 lines from the tank to IP. Pressure periodically drops below 10 psi at wot. I am thinking that I have a problem in the tank too. Electric gauge checked out with mechanical and same pressure readings. The only thing left is the tank issue. Did yo have any problems cleaning out the sock or screen that was in the tank? Thanks.

 

[DEWright]

lowfly, how low can you fly? I am having the same problems as these guys are. I have new 3/8 all the way from the tank to the pump to the filter and from there to the IP. Pressure at idle is 16-17, running it drops to 12, then on WOT, it drops to 6psi. What the hell? I have your ddrp on the frame near the tank where it was recommended being put by your distributors. I am leaning towards a tank issue also. I know that my gauge is correct, already checked it with a mechanical and they are both on the same plane. Pump does not have the screen in it because I did not use any of the banjo bolts to plumb the pump. Any other suggestions? Thanks.

 

[KLauber]

Where is it?

... ... something we ran into today... ... pull that screen that is in the banjo bolt and see if there is debris in there. Clean and reinstall. We had one that had 4 perfect circles in the screen where crap clogged it up. Issue was the same as you were seeing.....

Exactly where is this banjo bolt, so it can be checked?



Ken

 

[DEWright]

I didn't use banjo bolts on mine. I used the straight fittings and the screen doesn't work for that set up. Have you cleaned out your fuel tank? I think that this is going to be my next step. If you did, was the screen at the bottom of the tank module dirty? Thanks.

 

[CEdwards]

I just ran across this thread and would like to say that I also have the same intermittent fuel pressure problem and I have replaced every single component from draw straw I to vp-44. Dropping the tank for the draw straw was the last thing I did and I didn't see any problems. That was a little disappointing because didn't have any options left. Never had any problems other than low mileage since my rebuilt vp-44 until one day I got low fuel pressure. It changes from day to day with 3 different lift pumps, currently running ddrp which did the same as every other pump. I have had this problem for about 5 months now and yesterday I got the dead pedal and 0216. I'm actually happy it finally happened and my new vp-44 from blue chip with a new computer will be here in two days. If I put this on and still have fuel problems I am going to sell this truck and never ever buy another diesel of any brand. I get worked up just thinking about all the crap I have had to modify and fix and deal with on all 3 dodges I have owned. I don't know if changing injector pumps can fix irradic fuel supply pressure, but it better cause thats all I got left.

 

[DEWright]

Since my post, I have gotten all of my issues fixed. First of all, I pulled the tank and took all that old screening material, "that was clogged up", out of the tank module and pretty much put it all back in without any screen. I then put a napa in line fuel filter between the tank and the fass ddrp. I fixed the fuel pressure issues with the ddrp by getting fass to send me another spring that regulates the pressure in the pump. It allows more constant pressure. It idles at 22 and as you shove the coal to it, it drops below 20 but never lower than around 15. Some say this is too much, others say no. With all of this done, I have not had any other fuel pressure problems. You can check the pump by pulling out the original spring and stretching it just a little. Your pressure should come up, but you will still need to replace the spring with a new one from fass. They have just what you need. I read a thread that was written by a bosch employee that rebuilt vp 44's and his comment was, he has never seen a pump go bad with too much pressure, but he has rebuilt many that had too low a pressure. So far, mine has done good and as mentioned running about 22 psi on idle which drops down below 20 with acceleration. I hope this works for you as I learned from asking questions and making phone calls. My truck has 205K miles and runs like a fine tuned singer sewing machine.

 

[DEWright]

To all using the fass ddrp. Change the spring out in the pump that controls the pressure flow and your pump will do just fine. Call fass and tell them what you are experiencing and they will send you another spring and that will take care of the low pressure problems. Also get rid of all the trash in your tank and pull the screen out of the module that goes in the tank. Put an inline napa or equivalent in line fuel filter between your tank and the ddrp and you should be good to go. I changed all the lines out and relocated my ddrp near the fuel tank for convenience and I also changed all the fuel lines out running all the way to the vp 44. My pressure gauge attaches at the schraeder valve at the pump. Very good pressure! 22 psi at idle. This should fix your problems. good luck to you all!

 

[CEdwards]

Made 2 changes. Just got my new blue chip pump with new computer in yesterday. While it was down I replace the entire return line and the short rubber hose between filter and vp-44 supply line. Now fuel pressure is rock steady on 14 to 15 psi. The only odd thing is now when I first start the truck the pressure rises very slowly, it didn't do that before. Anyway at least it is finally running properly and I'm very happy with the result.