Engine/Transmission (1998.5 - 2002) Lift pump change

[jandr]

Can I get everyones input on when to change the lift pump. Plus a few comments on things I've read and heard.

My truck now has 103,000 mi on it. My existing pump was put on about 45,000. When I first put on my fuel pressure guage at about 80,000 mi. it ran around 9-10lbs at 70mph or so and 12 to 13 at idle. . Now its down to 7-8lbs. at 70 and 10 to 11 at idle. Dodge did what they called a flow test on the pump at 97,000 mi when they installed my new VP44 and they said it was good. Mechanics have told me that more than 13lbs into the injector pump is hard on them as well as to low of pressure. I read somewhere that the low side should not be below 4 or 5. Any thoughts or exact knowledge? I figured when it goes down 1 or 2 more I'll change it. I carry one under the seat but would rather do it in the driveway than beside the road!

 

[rweis]

Use to be below 10 psi idle, then ... . the DC rules changed, but not mine.



Bob Weis

 

[Mundgyver]

The VP-44 has an internal relief valve set at 14 psi. Anything higher than that gets routed back to the fuel tank. I put on a FASS unit. My truck runs allot smoother now than it did. The installation of the FASS reduced engin vibration and increased my fuel mileage. I get 22. 78 on cross country trips now.

 

[HEYBOSS]

Mundgyver, how did the FASS increased fuel mileage?

 

[Mundgyver]

The secret is in its ability to seperate air out of the fuel so all that the VP sees is fuel with no air bubbles. The engine run smoother with less vibration and less clacking in the valve train.

 

[clw1100]

Lift pump problem

I was looking at the Fass system. I posted in another topic. I think my lift pump may be going out. Last night after my drive home (about 40 miles) I wanted to "bump" my starter to just to listen to the pump. I "bumped" and NO pump noise. I had my son "bump" the starter while I was holding the pump (to fill for vibration or anything). The pump sounded and felt like it was pumping ONLY the 1-2 seconds the starter was cranking and then it would stop immediately when the starter was released. Did the "bump" test this morning and the pump made the normal 20-30 pumping noise.



My question - does the ECM turn off the pump voltage if the engine is fully warm ( after 40 mile drive home. ) ?? Is my pump dying?? Please inform.



PS - Piers just called to tell me that warranty on the Fass system is 60 days. He was still trying to get more info though.



Thanks.

 

[HEYBOSS]

No ecm does not turn off voltage when engine is warm, It could be your pump on it's way out. Usually electric motors (like the pump) when worn out can stop working hot and when cold work fine, seen this many times on gasoline engine cars, the fuel pump quits working when vehicle is driven for a while, let it sit and starts again.



Do you have a pressure gauge? To me that's a must on these trucks and I've replaced my LP three times before it completely clunked out on me, once on a 3000 mile camping trip I seen the pressure down to 5psi, it gave me plenty of warning time to be able to find another pump and replace it before I took out the VP and got stuck.

 

[Mundgyver]

Someone can chime in here if I am wrong, but I was under the impression that the lift pump, in my case my FASS system shuts off once supply pressure is reached within the VP. I say this because in the mornings or after a long parking interval you will hear the pump wind up and then stop. The pump pressurized the feed line to a pressure seen within the inlet of the VP. Once that pressure has been reached the VP sends a signal to the ECM which in turn controls the LP circuit to shut down untill the pressure drops.



I say this because the FASS system plug right into the LP harness and this is how it acts. There is no pressure switch within the FASS unit that would act as a cut out. So its information to stop pumping has to come from the ECM which is looking at the VP pressure.



Is there anybody out there that knows if this is not correct??

 

[cam4g63]

The VP doesn't send a signal to the PCM to shut down the LP, in fact there are no pressure sensors anywhere in the system. If my reading of the FSM is correct, the LP receives a short duration power signal at half the normal voltage to prime up the VP44 with just enough fuel to start. Once the engine starts, the LP receives the normal 12 volt continuous power as controlled by the PCM. I am not familiar with the FASS, does it use the power source from the LP connector? or does it get triggered by the LP electrical source and the FASS pump itself get it's power from the battery through a relay?



I'm considering the FASS, because right now that 14psi return valve and line in my truck flows ZERO fuel!! :{

 

[Mundgyver]

I am not familiar with the FASS, does it use the power source from the LP connector? or does it get triggered by the LP electrical source and the FASS pump itself get it's power from the battery through a relay?

The FASS system comes with a harness that plugs right into the LP connector at the LP. Works very nice. Harness has a fuse in it wich il located near the FASS. The fuse is in a weather proof module.

 

[Cliffman]

okay, I give up. What the f?ck is a FASS

 

[Mundgyver]

http://www.piersdiesel.com/FASS.htm



Here is what a FASS system is. I believe that this is the ultimate replacement for the Lift Pump. I'm getting 22. 78 mpg and less vibration during accelration. Too bad these pumps are used as a stock pump for the trucks.

 

[DLBurns]

The Fix

Originally posted by Cliffman

okay, I give up. What the f?ck is a FASS

Hey Cliff... . This sounds like the ticket to eliminating the LP problems we all are having. I'm gonna have Blair install one when he does my Tranfer Flow OEM tank replacement! My LP is still kicking... just don't want to take a chance on it ***&^ing the bed on me along ways from home!

 

[clw1100]

Relay use on FASS

Doug at Smokindiesel modifies the FASS harness on the system he sells. He puts in a relay to draw power from the battery and uses the signal from the ECM to actuate the system. He also labels the harness real neat and all.



They also offer a "higher" flow model that basically runs 1/2" tubing (instead of 3/8" on the standard kit) from the fuel tank to the VP. Looks like a dang hose pipe snaking up thru my truck frame. BUT it FLOWS alot of juice.



clw1100

 

[Cliffman]

BUFF, Not if I get mine first :-laf :-laf :-laf

 

[Ray Torresdal]

How?

Does the FASS system have a vent to release the "entrapped" air? I'm still not sure I understand how this is supposed to work.



Ray

 

[Mundgyver]

First filter 100 um seperates out the water. The fuel flows from the very top of the filter out. The second filter 10 um has a dip tube the protrudes to the bottom of the filter. All fuel must pass through the bottom end of the filter. All air goes out the top through a secondary outlet that is parallel to the dip tube and is pumped back to the tank.

 

[Rockcrusher]

Sounds like the FASS is the way to go. Anyone have picture of how its installed? Cost?

 

[Mundgyver]

I'm waiting for my digital camera to arrive so I can post pictures. Cost is in the $500 range and I understand that they now make one with a 1/2 inch ID supply line besides the 3/8 inch ID supply line. Thats getting pretty big.

 

[DLBurns]

Ha Ha

Originally posted by Cliffman

BUFF, Not if I get mine first :-laf :-laf :-laf

I live to close to him not to be first in line!!

Looks as though I may need to get my tent out and pitch it on his new lawn!