Engine/Transmission (1998.5 - 2002) Fuel filter canister won't re-fill.

[Joe Gerber]

Don't want to beat a dead horse, and I have gone back and read some old threads, but still have a problem/question.



I changed the fuel filter (Removed old filter, emptied canister and wiped clean, installed new filter and re-installed canister. ) and tried to re-fill the canister by cracking the test ports on the top of the canister and then bumping the ignition to get the lift pump to run. I cycled the lift pump 8 times, but no fuel showed up at the test ports. I took the canister off again, and there wasn't any fuel in it. I have changed the filter myself six times in the past and haven't had a problem



I called a Cummins shop and talked to a tech. I asked if he thought the lift pump was bad. He said that if I could hear the lift pump running, it should pump fuel. I'm not sure I believe him, and would like some other opinions. The lift pump sounds normal to me.



Also, this is the original lift pump. The truck has 112K on it. I don't have a fuel pressure gauge (shame on me). The fuel tank only had about 8 gallons in it when I started. The Cummins tech suggested adding some, which I did. Now have about 24 gallons in stock tank, but lift pump still won't pump.



What do you guys think? Am I missing something, or do I need to replace the lift pump?

 

[Gary - K7GLD]

Replace the lift pump...

 

[klaybus]

What Gary said... ...



Clay

 

[Huff N Puff]

What Klaybus and Gary said

But after you do check the voltage and ground at the fuel pump connector,the reason for this, is a poor power supply can ruin your new pump. Cummins has the engine computer actully powering up the pump. Any problems in the pump such as debris getting into the pump,because it is on the non filtered side,can spike the amps which can hurt the driver in the computer. This is a possible reason for so many pump failures. To fix this problem I suggest you use the power circuit from the pump actuate a relay,which turns on your pump. Merv

 

[LStanphill]

Lift Pump.

Huff : Could this cheesy power supply issue cook my fass motor? Guess I better put it on a relay, Huh?

 

[Ncostello]

Its not the motor you should be worried about LStanphill. Its the computer delivering the power. High amp draw because of something physically bogging the motor will hurt the computer driver. After such an episode the motor will basically go back to normal but the electrical components of the computer may not.



By going to relay power... the relay will pretty much draw constant low amperage from its computer derived power source. The computer power only need switch on the relay. Then the relay connects the battery direct to the pump. Any spikes in current draw will go directly back to the battery. Thus your computer is isolated from the high current draw via the relay.



FASS, Preporator or stock... it all applies.



Personally I have no problem driving my Carter OEM pump relocated with extended stock wiring. But anything else like a pusher pump or a big motor on a FASS should get relays for sure.

 

[Huff N Puff]

For LStanphill

Your FASS should already be powered by a relay if you wire it properly. Merv

 

[Joe Gerber]

Thanks for the input. I'll put on a new pump.



What fails in the pumps? I was confused by the Cummins mechanic telling me that if the pump motor is running, the pump will move fuel.



Merv and Ncostello, it sounds like there should be 12 volts at the pump. Thanks for telling me. I'll check it.

 

[elamb]

When my lift pump went out, it would run, but the gauge stayed on 0.



Eric

 

[CDenton]

Mine did the same thing, changed filter went to prime,the pump would run but no fuel to filter. lift pump was OUT.

 

[Gary - K7GLD]

"What fails in the pumps? I was confused by the Cummins mechanic telling me that if the pump motor is running, the pump will move fuel. "



The inlet filter can be clogged



the floating rotor vanes can be gummed up and not functioning properly



The plastic/nylon shaft coupling between the motor and pump rotor can be broken



The internal bypass spring can be broken, allowing greatly reduced or NO flow pressure...



That should do for a start...

 

[rweis]

1. The inlet filter can be clogged -- That can be cleaned (I think pre filtered fuel would prevent this)



2. the floating rotor vanes can be gummed up and not functioning properly -- That can be cleaned (I think pre filtered and lubricated fuel would prevent this)



3. The plastic/nylon shaft coupling between the motor and pump rotor can be broken -- That would be a problem



4. The internal bypass spring can be broken, allowing greatly reduced or NO flow pressure... -- Don't let the flippen thing function in the first place! ie a Mallory 4307M prevents this



Let's see, that leaves #3 and that would definitely be a problem. As I recall reading threads you can not take the pump apart without destroying it right? Looks like it could be time to check the DTT folks about the KO Engineering RASP.



Bob Weis

 

[Joe Gerber]

Thanks for the info. And thanks for making the TDR so useful and enjoyable.



Joe

 

[kscheffler]

Current Lift Pump Part Number

What is the current lift pump part number for the Gen 2's? Thanks

 

[truckstom]

Re: Current Lift Pump Part Number

Originally posted by kscheffler

What is the current lift pump part number for the Gen 2's? Thanks

3990082

and

3990105

 

[Joe Gerber]

Before putting in the new lift pump, I checked the voltage going to the pump.



After bumping the ignition, the voltage was 12. 4. I was surprised when the voltage only dropped to 9. 0 after about 20 seconds. I expected it to drop to 0. 0. Is this normal? The voltage at the batteries was 12. 8.



By the way, the new pump filled the fuel filter canister very fast, and the truck started after about 5 seconds of cranking.



Joe

 

[Gary - K7GLD]

Joe, if you're inclined to do so, sure would be interesting if you would take off the bottom plate of the pump for a look-see inside to see if you can determine what the exact failure was - the pump vanes simply float in their slots, and if you manually turn the pump rotor, you should get some motor armature resistance - actually, you CAN simply pull the rotor out of the cavity to see if the plasic connector is still intact. The inlet screen is also clearly visible, and an allen wrench can be used to reach in to see if the bypass valve ball is seated and has spring pressure... Since the pump motor was working, there pretty much has to be a problem in the pump itself...



I've personally never bothered to check for the exact voltage drop on my LP after the initial key-on bit, but yours is probably normal...

 

[RPainter]

replacement pump

how hard is it to replace the fule pump? Just changed mine and she won't fill by itself so asume she is dead. Also, is it a cummins part or a dodge part? Where can I get a good price on a pump without getting reamed from dodge? Thanks

Randy

 

[Gary - K7GLD]

Usually a better price at a Cummins shop - not real hard to swap out, other than the dern loctite they use on the mounting bolts...

 

[Joe Gerber]

Gary,



I opened up the pump. The inside looked very clean to me. A slight varnish type discoloration on parts of the impleller blades. The blades move easily inside the slots. The screen was perfectly clean. I could see the by-pass ball. It was pushed all the way towards the motor and I could see what looked like a spring keeping it there. I tried pushing it farther towards the motor to make sure is was seated. It didn't move. When I shook the pump, the ball didn't come unseated, or at least it didn't rattle. The plastic coupling appeared to be fine. The motor shaft turned easily, and I could feel the armature resistance. There were 12 'pauses' in one revelution of the shaft.



I connected the pump to 12 volts on the bench, and ran it. The pump rotor was on the motor shaft, but no impellers. I pushed against the rotor with my thumb trying to put the motor under load and couldn't slow the motor down.



The only thing that seemed wrong to me was the motor rpm. I expected it to turn faster. My guess is that it turns approx. 700 rpm. I could be way off though.



Joe