Engine/Transmission (1998.5 - 2002) Still Have Low FP With New Lift Pump. What's Next?

[trqmnstr]

I replaced my lift pump about 10 months ago. Pressures were 15 idle and 12 WOT with the new pump. They gradually lessened until I was at 12 idle and 7 WOT. I replaced the lift pump again 2 months ago. The new pump gave me 13 idle and 10 WOT. Now, I am at 12 and 7 again. I'm getting the pump warrantied tomorrow so we'll see if it's the pump or something else. If the numbers are the same, what is the next step? Clogged pickup? I need some sound advice. Thanks Clay

 

[rweis]

Try powering your lp through a relay so it gets FULL battery power. LP wiring triggers the relay, battery powers the lp.



Bob Weis

 

[nps]

Put a pusher on it. Mine had slid to 9psi idle, 7psi cruise and 5psi WOT. Put a Carter 4600 by the tank without replacing the LP and pressure is now 14/12/9 and rock steady. Less than a $100 solution and reliable given others experiences.

 

[SnoKing]

Pull the LP relay and put some dielectric gease on the contacts. SNOKING

 

[trqmnstr]

I would like to add a pusher but I'd rather fix the problem instead of putting a patch on it. Once fixed, then I'll add the pusher. I had good FP with the stock setup so I know it's possible. I've read about clogged pickup tubes. Possibility?

 

[GarrettPetersen]

Ive seen where the fuel heater causes a major restriction. it was removed and the pressure went from 0 at WOT to 15 steady. the setup was the FASS 95 setup

 

[Gunhill]

Trqmnster,

I understand your frustration. About 3 weeks ago I installed a new lp after constantly getting 7-8 psi out of the old pump at idle. The 1st day or so with the new lp my pressure was right at 15 psi, after that it dropped to about 10 psi when idling on most days. If I had been driving on a rough country road or filled up I noticed my pressure would drop to 7-8 psi at idle for a day or so. At about 2K rpm it will drop about 2-3 psi. I have a mechanical gauge so no wire connections to worry about. I figured I had sediment in my tank as I also noticed when I changed filters my pressure would be 14 psi for a few miles or so before dropping back to 10 psi and I know the filters don't get dirty that quick. I only buy fuel at truckstops that I trust and I check the nozzle for dirt in case the last guy happened to drop it etc.

My theory was anytime I opened up the fuel system it would allow a bit of a backflush to the tank... maybe this isn't true if there are check valves etc... I don't know. I dropped my tank over the weekend and I couldn't believe the sludge and sand etc in my pre-filter that's on the fuel module set-up. I also un-hooked the line at the lp and blew an air through it to blow out any sediment in the line. 17 psi with a stock pump for 2 days. I'm now about 14-15 psi after running it for 4 days. Granted that's not much to stand on but looks promising. With all of the new lp's going in and guys have poor pressures way to soon I'm wondering if they have similar amounts of sludge and sediment in their pre-filters. The pre-filter does a heck of a job as the fuel in the tank itself was clean. The downside of the deal was that I scratched the pre-filter when cleaning it and tore it. I don't know if that will create issues or not in the future with sediment. I'd almost bet my right arm that Dodge won't sell the pre-filter separate!



I've got an 02, HO with 130K on it. I don't know if your set-up would be similiar or not but figure it would be.



brad

 

[JoshPeters]

Gunhill,



Go aftermarket. They sell those little screens.



At least in all the gas jobbers I've replaced... they have.



Josh

 

[easleyj1]

I also fought the problems you are seeing. My pressures were about 13 idle, 9 cruise at 2000rpm and about 5 wot. I did the pusher pump with the 4600 Carter and so far I have 22 idle, 17. 5 cruise and 15 wot! I am very pleased with this. I have had 4 LPs on my truck and found that new they were prone to have very different pressure readings. I can't remember which pump it was but the best idle pressure it ever achieved was 12 psi.



Jonny

 

[Gunhill]

Josh,

Any part numbers handy for those screens to get me started?



thanks

brad

 

[rivercat]

be sure and check your gauge connections/ isolator mine had leaked out its antifreeze and after filling it back up and tighening the leaky connection my normal readings came back.

 

[JasonCzerak]

i'm at about 55,000 miles. I'm planning on a FASS this month.



With this young of a truck, ya thing It would be worth my while to drop the tank and get at the prefilters and all that and clean the tank?



No Fure Pressure guages yet tho.

 

[JoshPeters]

Josh,

Any part numbers handy for those screens to get me started?



thanks

brad

Not on hand. I'll try to call the parts stores tomorrow.



Josh

 

[trqmnstr]

Gunhill, I think I may drop the tank and see what I can find. I have 175k miles so I know it's time. Also, my fuel gauge quit working. What does it take to fix that?

 

[Gunhill]

It doesn't take much to drop the tank... just have a transmission jack or maybe jack stands etc to set the tank on until you can get it all unhooked. With 2 or 3 gallons left in mine it wasn't heavy just awkward to handle. Probably not a bad idea to blow or wash the dirt off the top before you start disconnecting hoses. You might want to invest in a 15mm deep socket otherwise you'll have to unbolt the carrier bearing... if you have one... and tie it out of the way to get a wrench on it... I couldn't use a normal box-end wrench. I had to use an offset wrench to get into the 'channel-iron'. My fuel gauge was working when I dropped my tank but I'm thinking the part you replace is on the side of the fuel module. Somebody has a line drawing in their readers rigs section. Below I've attached a couple of links that may help too.



https://www.turbodieselregister.com/forums/showthread.php?t=112551 If I'm not mistaken the red and blue wires on one of the pictures runs to the fuel gauge sensor.



https://www.turbodieselregister.com/user_gallery/displayalbum.php?&userid=13345&albumid=933



May not be a bad idea to have some extra hose clamps handy as well. DC clamps seem to be a one use item or at least a real pain to re-tighten. Hope this helps.



Josh, If you get time to call the parts stores great... if not, no worries I can call just as easy myself. Thanks

 

[trqmnstr]

I think I'm going to drop the tank tomorrow. Question: Can I slightly lower the tank and reach on top to disconnect the fuel lines?

 

[trqmnstr]

I just dropped the tank. The piece that floats on top of the fuel had come off and started to break down. That's why my gauge quit working and the debris was clogging the pre filter. That's my best guess. I also tore the pre filter screen when removing it so I'm on the hunt for one, too. Gunhill, any luck finding one? Also, is the little float a factory piece?

 

[rweis]

What kind of material was the float? Could it be replaced with a brass float?



More "stuff" that can get into the fuel system



Bob Weis

 

[trqmnstr]

I'm not sure of the material. It's a porous floation material surrounded by a hard casing. That's all I know.

 

[Gunhill]

Trqmnster,

I've not made myself go to the parts store yet... the plan is for tomorrow morning. Hopefully you have had luck locating these parts in the past couple of days.



brad