Engine/Transmission (1998.5 - 2002) Replaced lift pump, but now loosing pressure

[SReiger]

I have a 2000 ctd with 204,000 miles. I've replaced the lift pump and injection pump once already. I noticed my fuel pressure started becoming erratic, it would jump from 12psi going down the road to 5 or 6psi. So I got a new lift pump and put it on right away. Worked great went for test drive and couldn't get it to go below 9 psi no matter where the edge was set or how hard I pushed it. Two days later I had a job about 200 miles away. I have a fairly heavy service body on it and I hooked up a trailer that weighed at the most 3000lbs. On the way up it was great, at 70 mph it held right at 11-12 psi. On the return home, I had a hard time keeping it at 5 psi with an empty trailer! If I accelerated hard or pulled a hill I could easily drop it to 1psi. I had to baby it home to keep it in the 5 psi range. What happened??? Bad injection pump? Bad new lift pump??? What should I look for? I really can't afford another injection pump. Thank you for your help!!!!!

 

[JLandry]

Greetings,



Double check the fuel pressure using a separate mechanical test gauge hooked up to the inlet at the VP44. You can buy a test gauge from Geno's Garage here:



VULCAN PERFORMANCE - FUEL PRESSURE TEST KIT ('98. 5-'02)-Dodge Cummins Diesel Truck Accessories – Geno’s Garage



or on eBay.



I've had a couple of good low fuel pressure scares while which turned out to be nothing more than faulty pressure readings.



Good luck,



John L.

 

[DavidC]

Fuel Filter?



Dave

 

[Missouri Mule]

Overflow valve?

 

[Sticks]

OEM lift pump design is crap?

Either add in the Mopar in-tank update in addition to the block mounted pump, or go completely aftermarket (Fass, Air Dog, Rasp... ).

 

[SReiger]

Just changed the fuel filter, overflow valve seems rare, but I'm going to have it checked out. It's an airtex pump, should I had another inline to it, if this works?? I've got 60 hp injectors and the edge 5 step box. Usually run in level 1, unless I need to pass someone on the 2 lane road. Thanks for the advice everyone. Seems I was getting around a 100,000 miles from the oem pump. Will FASS go 300K? or ? How much better are they for the money?

 

[SReiger]

One other thing I noticed was that it was starting harder once and a while on that return trip also. I had to crank a bit longer before it fired off. Almost acted like my 06 CTD. Usually I barely touch the key on the 00 and it's running. Maybe this will help? Thanks again everybody!

 

[Missouri Mule]

Don't the 24 valves have a rubber fuel somewhere in the fuel return side, if it started to get airline cracks it could be sucking air.



Since you have fuel pressure guage when you find that rubber return line take a pliers and squeeze it, if the pressure goes up it is your overflow valve, if doesn'g go up or goes up slowly it is your lift pump.

 

[WestTN]

It sounds like you have some contamination in your fuel tank that graually is drawn back on the pickup screen.

 

[SReiger]

Well here's what we've found out. Tested pressure before and after filter, changed lift pumps, tested for restrictions to the tank etc. It turned out to be a bad new airtex lift pump. Going to replace it again this week. I hope this one lasts longer than 200 miles! Thinking of adding another inline pump down on the frame. Does someone make a kit for that? Do you just splice the existing pump wires are does someone make an adapter? Thanks for the help.

 

[CEdwards]

I experienced the exact same thing. Noticed my pressure suddenly running 5 psi after 2 years with an airtex that always stayed at 15psi or above. Pulled in to oreillys on a sunday morning (only thing open) and tried changing filter first. Would not prime, never had that problem before. Pulled hose off pump and was only getting a trickle. Went inside and got another airtex for $160. Installed and tested, gushes diesel. Go for a test drive and it's just like new. An hour later it takes a spell of 5 psi for a while but then goes away. Next day normal pressure. Next day low pressure. No rhyme or reason. It can run high for a while and then run low for a while. It is very frustrating. I feel like I just wasted $160 and I probably need to waste some more money on an aftermarket. Will an aftermarket pump be a permanent solution???

 

[CEdwards]

I experienced the exact same thing. Noticed my pressure suddenly running 5 psi after 2 years with an airtex that always stayed at 15psi or above. Pulled in to oreillys on a sunday morning (only thing open) and tried changing filter first. Would not prime, never had that problem before. Pulled hose off pump and was only getting a trickle. Went inside and got another airtex for $160. Installed and tested, gushes diesel. Go for a test drive and it's just like new. An hour later it takes a spell of 5 psi for a while but then goes away. Next day normal pressure. Next day low pressure. No rhyme or reason. It can run high for a while and then run low for a while. It is very frustrating. I feel like I just wasted $160 and I probably need to waste some more money on an aftermarket. Will an aftermarket pump be a permanent solution???

Or is there anything else I should be looking for? I already replaced rubber line. Something in the tank? Erratic leak in suction line? I'm getting frustrated. The only way I can rule out everything but the pump is to replace everything but the pump.

 

[JLandry]

Or is there anything else I should be looking for? I already replaced rubber line. Something in the tank? Erratic leak in suction line? I'm getting frustrated.

That's what I would be looking at next... possibly something intermittently restricting the fuel pickup inside the tank.

The simplest thing to do might be to bite the bullet and buy a new version of the Vulcan Performance Draw Straw I, drop the tank, and install it in the fuel tank module. That would positively eliminate any fuel restrictions or leaks up to the lift pump. While I haven't installed a Draw Staw myself (yet), I understand it can be done in such a way as to almost completely eliminate any concern of not being able to get all of the fuel out of the tank before sucking in air. Essentially it means eliminating the mesh screen at the bottom of the fuel module then making sure you cut the draw tube square so it goes all the way to the bottom of the tank, then you make two or three notches the end of the draw tube. This causes it to draw fuel right off the very bottom of the tank. There are some good how-to web pages and videos if you search Google.

While you're going through the effort of dropping the tank, you might as well also relocate the lift pump to the frame rail just ahead of the tank. Not only does the lift pump work better there, it's literally a 10 minute job to replace. Vulcan Performance also sells a complete relocation kit.

Good luck,

John L.

 

[Sticks]

A broken standpipe in the tank is not unheard of.

Personally I am partial to the pickup screen in the tank, it keeps the floaters from moving upstream, and you would be surprised what ends up in your tank.

The new style in-tank liftpump/fuel sending unit is (or was) cheaper than the non pump version. Might be worth upgrading to that.

 

[CEdwards]

Had only 5 psi on the 24 mile drive home from work today. Was thinking about what to do next as I was babying it down the road. I know it's not the back flow valve because if I i bump the starter it will get past 20psi. If I start it, it runs at eight. That kind of tells me that the back flow valve and the pump can put out the proper pressure but not the volume. If I have time tommorow I think I will run a rubber line from the pump to my tank on the back of the bed and drive it for a day or two and see what happens. I did this once on my 12 valve and just stuck the hose in the filler tube and drove on. This will eliminate all possibilities other than the pump. I don't know why I didn't think of that yesterday. Sometimes when you get frustrated you have to just think on it for a while and you can usually figure it out. will report back when I find the problem.

 

[CEdwards]

Ran a fuel line from my tank on the back of the bed to my fuel pump. Then I drove 20 miles with the highest fuel pressure I've ever had. 22psi @ idle, 18psi going 70mph down the highway. That shows I definetly have a problem in the suction and the factory design is crap. If anyone tries this don't forget the return line. My factory tank was at 1/4 so I just let the overflow fill it up. Before I drove the 20 miles it was overflowing out the filler cap and I had to switch it back to the regular fuel line to drive home. This also shows just how much excess fuel the lift pump is capable of moving even against 18 to 20 psi. It makes me realize that the factory lines are a minimum at best for a stock truck. It is really under engineered. By the way the hose I ran was 3/8 about 15 feet long, far longer than the normal distance between pump and tank. There should be more restriction in that I would think. Will be upgrading the whole system now.

 

[JLandry]

Personally I am partial to the pickup screen in the tank, it keeps the floaters from moving upstream, and you would be surprised what ends up in your tank.

When using a Draw Straw, any concern from debries in the tank is easily eliminated by installing a pre-filter between the tank and the lift pump. The plastic mesh screen in the tank is essentially just that... a pre-filter.

Here's a nice cleanable inexpensive pre-filter with a stainless steel mesh screen suitable for stock flow rates:

Pre-filter

John L.

 

[JLandry]

Will be upgrading the whole system now.

Glad you isolated the problem.



You can find all the parts you need for redoing the fuel system here:



Vulcan Diesel Performance



Good luck,



John

 

[CEdwards]

Have still been fighting erratic fuel pressure even after installing ddrp. Eventually it got to where it would actually run on a vacuum. So this definetly proves why people need to have fuel pressure gauges installed. A dodge diesel will run no problem with no fuel pump running. Got the 0230 code and started doing some research on here. Got it narrowed down to ECM. I found a post by Jlandry showing how to wire a relay to get the supply voltage out of the ECM. At this time I have it wired through a toggle switch, which I wouldn't recommend because someone might forget to turn it off or on. I have one that lights up when it is on and it is mounted next to my gauge. As I read all the many many posts on here about people having erratic pressure I wonder if the ECM was just giving erratic voltage. Looking back now I don't think there was anything wrong with the last two pumps I bought. Each time I would turn the key off and restart I could get a different pressure. Lately I would have to cycle the key on and off 4 or 5 times. The only way to test would be to hook up a voltmeter permanetly and drive around monitoring it for days. Mine wouldn't always act up so I never really caught on to what was happening until it finally went to 0 volts. All I know is 2 airtex and one ddrp were all giving erratic pressures but not now with their own circuit. This is with 100% all new components in the fuel system, completely aftermarket from draw straw to filter and replaced overflow valve. All along it was electrical. At least I got some good experience and learned a lot about the fuel system. By the way I also kept an airtex mounted and ready to go so I have 2 fuel systems that I can control from the cab so I will feel pretty confident on the next trip. Hope this helps somebody figure theirs out.

 

[CEdwards]

https://www.turbodieselregister.com...-2002/201927-erratic-fuel-pressure-p0230.html Here is a good thread that helped me out and shows how to wire a relay and some other trouble shooting related to my problem.