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 Cummins lift pump issues ??
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valleybusman
Top Member

USA
798 Posts

Posted - 06/29/2017 :  11:02:22 AM  Show Profile  Send valleybusman an AOL message  Reply with Quote
I have a 03 TC 2000 . We have had issues with the service engine light . So I figured since we are down I would dig into it . I pulled the filters and the primary had a bunch of gunk . Pulled the secondary and I cleaned the housing out . Went to prime the system and can't get the secondary to fill up . Tried 20 times by bumping the engine . Got maybe an inch of diesel . No more then that after trying 10 times to bump the engine . I can hear the pump running after bumping the engine and leaving the key on . Then I looked down in the filter housing and see some shiny stuff . I want to know if I am on the right track that it is the lift pump ? Also I can not find the engine serial number to order another one . On a tag inside the bus it says 46181500 is the engine and L051891 is body . Can someone validtae my findings here ? Thank you

krmvcs
Advanced Member

362 Posts

Posted - 06/29/2017 :  11:12:54 AM  Show Profile  Reply with Quote
Sounds likely that youve got a bad lift pump. And if any of that metal gets to the injection pump its a goner too. Just for fun you could run power to the pump and let it run into a container and examine how much fuel you get from it. And also see if its adding a bit of sparkle to the fuel.

-Ken-
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RonF
Top Member

867 Posts

Posted - 06/29/2017 :  11:19:00 AM  Show Profile  Reply with Quote
Sounds like you are on the right track.

Here is the cumming lift pump number for a serial number close to yours. I can't add anymore to my insite.
3990105
Napa numbers, 2299001, HFP 923, DTP 300, or B0100E.


Insite also says you may need to manual bleed the system if you have had the lines off.

US Army retired CMBT
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BigPapa
Advanced Member

215 Posts

Posted - 06/29/2017 :  12:01:48 PM  Show Profile  Visit BigPapa's Homepage  Reply with Quote
Your ESN is 46181504. Your lift pump number is 5362273.
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1stLtDan
Active Member

USA
13 Posts

Posted - 02/16/2018 :  08:40:22 AM  Show Profile  Reply with Quote
NEWS FLASH - updated lift pump number from old number 4943048 is :
5362273

Main point is to start with the newest lift pump if you spend money to replace a suspected weak lift pump.

Clean fuel filter, clean fuel, new air filter should all be verified. Scan the computer and address any concerns on sensors. Crank and cam sensor can be weak and not set codes. Cam sensor is up behind the VP44 injection pump where the old 12 valve timing pin was located. The crank sensor is below the electric lift pump on the side of the engine above the oil pan railing.

Here is the shortest version of my understanding of the VP44 5.9 Cummins , 24 valve engine.

The small lift pump is mounted on the left side, drivers side just behind on slightly below the fuel filter assembly. Have someone turn the ignition key to the on position. Place your hand upon the lift pump. Have them crank engine then immediately stop cranking with the key placed in run position. You should feel the lift pump vibrating strongly. At this point you know the computer is calling for the electric lift pump. If you have a pressure gauge you need to place it between the fuel filter and the VP44 Injection pump. Now if your electric lift pump is not reading a minimum of 10 to 15 psi it is weak, or there's restriction at the fuel filter or fuel return line check valve may be open all the time. It is at the rear of the cylinder head in the fuel line junctions. You could also be loosing prime in fuel line between pump and fuel tank. Take the fuel cap of the tank, use a shop rag and an air blower and wrap rag around your air blower. Gently trigger your blower on and off for short periods of time while someone cranks the engine through a few cycles of cranking for 30 seconds then rest starter for 15 seconds and try it again. If it starts and runs you'll at least know your VP44 has not seized up yet. If it doesn't start after this, use a little ether in spurts, not constant. You do not need allot of ether. If it won't start now here is another thing to check. Loosen three fuel injector lines and have someone crank engine over several times. If you have fuel coming through one line the VP44 is stuck on that cylinder, if nothing is coming it's stuck between cylinders which can happen. If it's coming through all three lines remove air filter and see if it is stopped up or has been water logged and sucked into the engine.

Here is something I like to do to verify electrical at the lift pump. Use your volt meter and connect straight pin to the back side of the lift pump connector plug. Place pin out clips to the positive and negative points. Plug the connector back in. Place meter up by windshield where you can easily see it while trying to crank your engine.

You should be reading battery voltage. Anything less - you have a wiring issue with resistance or possible wire breaking in the harness frl. Computer to the lift pump. The computer grounds the circuit for the lift pump to run based upon seeing a signal from the crank sensor. If no power at all is coming from the computer - replace the crank sensor at the side of the block just below the lift pump area.

So you see there's several things to consider and I haven't covered them all.

It's rare to have a computer issue. The old lift pumps has deficiencies. The new number quoted above, you should Google or Bing it. It is supposed to have a new design feature that does not restrict fuel flow should it also fails to operate in the future. I just put this one on an engine.

Start out with a new fuel filter. Make sure the tube you slide the fuel filter down inside the filter housing is NOT loose. Pour clean filtered fuel into the filter housing so you start out with fuel already there. This way your lift pump is not starting out dry with no fuel to keep it lubed.

At my fuel gauge after tapping the starter through a couple cycles the electric lift pump built up to above 15 to 16 psi.

Now what I did was wire in a light for my dash which I pigtailed of the positive side of the lift pump connector. I used an old Carpenter amber dash warning light and grounded one side to the dash metal. Any low output light should work. Use you imagination. Just don't use real bright ones or you'll have to cover it with some black tape.

I placed it up above the ignition key area. What this does to help is this. You have no way of knowing if your lift pump is on. This light tells you when you are definitely getting voltage to the pump. Now, when you first turn your key on so the intake heater actives you should see this newly installed light flicker. If not, tap the starter. Now it should either flicker once or several times then stay lighted up for approximately 20 to 25 seconds then the computer will cycle it off. You'll need to turn the key back off for a few seconds. Then you can cycle key back on to verify the flash from the computer. Then crank engine. If it starts the light should stay on the entire time until you shut the engine off. If engine fails to start. Key cycling the key and bumping the starter several times until your lift pump had built up fuel pressure. If there is nothing wrong with the VP44 pump and you have fuel coming through all loose injection lines start tightening the injector lines if they are still loose. Crank engine once more and it should start.

Remember me saying to verify the air filter. I have seen a few air filters get sacked in to the engine which is rare. If basic maintenance is completed upon your fleet of buses then your filters are changed upon a scheduled time frame. You may have to remove your valve cover, crank engine and make sure all valves are moving. So you see you keep getting deeper and deeper into mechanical issues once you have ruled out that the fuel system should now be operating as designed.

I hope this article has helped someone.
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