lift pump dissected pics

[icarus33]

With the latest rev. of pump, getting 14+ psi @ idle, 13 psi@ cruise, and 8 psi @ WOT.



Here's a pic of the pump head and impeller. The vanes are not spring loaded and require centrifugal force from rotation to draw the vanes out to the pump casing. Notice the motor shaft sits offset for the impeller.



There's also an inlet screen, a kind of boulder catcher. I can easily see where a bad load of fuel could have contaminants that would jam up the blades.



Do I dare suggest that we may need a filter before the lift pump too...



ic

 

[icarus33]

Here's the backside of the impeller. Note the ceramic shaft coupling in the center where the motor shaft contacts. This mechanical "fuse" I would suspect is what comes apart during a complete failure where there is no pressure. The motor would be left spinning.



ic

 

[icarus33]

Motor shaft offset in housing.

 

[icarus33]

All the guts. The round disc is the cap for the pump.



ic

 

[work2muchplay2little]

Nice autopsy . Was this pump on its way out?

 

[icarus33]

The old pumps pressure was in the ballpark of other low readings. 11 @ idle, 10 @ cruise, and 4 psi @ WOT.



Injector pump supply was a concern. Since my engine was also an April '98 build, there's no telling if my VP44 pump was one that may have missed a deburring process that has been talked about. I would figure it would have died by now though.



ic

 

[David Oxland]

Some one commented that the vanes were driven out by centrifugal force only; can you tell if the is a connection from the backside, meaning the center edge of the vanes to the pressure side of the pump? This would mean that when the pump is loaded and making pressure more load is applied to the vanes or vice versa if it runs dry that the vanes tend to unload a bit?

 

[chuck3]

Thanks

Thanks for shareing the pictures with us ic. good job.

 

[Doc Tinker]

Good post, icarus33



Doc

 

[JEMOORE]

Thanks IC

Thanks IC, this is what everyone who has a lift-pump failure should do. I tend to agree, I think we need the filter, although I think it would put more load on the lift-pump. Leaving on 3800 mile round-trip tomorrow (KY-Mt. Rushmore-Thunder Bay-Sault St. Marie-KY) You bet I have a spare lift-pump, hope I don't need it!

 

[JPhillips]

Lift Pump Failure

I was at the local dealership the other day and got to see a lift pump that had failed and been taken apart. The only reason for this pumps failure was the check ball on the inlet side of the pump had came out of its socket. The pump motor still ran fine, but it was just by-passing the fuel internally. You can barley see this check ball in one of the pic's posted above. My friend that works at the dealership said that he has seen more than one of them with that same problem. Seems like there are several reasons for these darn things failing. I have a re-placement ordered due to the fact that mine is weak. I hope I can keep it for a spare though. Chris

 

[icarus33]

David,



As far as any "hydraulic" assistance applied to the vanes, there is none. No channelling of pressurized fuel to assist in placing force on those vanes against the pump bowl.



I ran this thing briefly with the cover off using a battery in the garage. This thing really spins and makes a heck of a racket, similar to a slot car. After cleaning it up and leaving some lube inside, it'll do for a spare in a pinch.







ic

 

[David Oxland]

Icarus,

Did you come to a conclusion about the trouble; a stuck vane or bypassing regulating valve? The thing actually looks in pretty fine shape. I wondered if that pressed in relief valve could be refitted?

 

[icarus33]

Nothing was obviously wrong for the low WOT pressures. I suspect there were low readings even when new. I saw a post where someone had good pressure at one time and then the idle pressure dropped 2-3psi and WOT was about half later on.



The actual tolerances of the pump would seem to be a large factor in maintaining pressure. As the components wear, pressure drops. I wish it was known what the changes have been with all the Carter pump revisions.



ic

 

[RustyTRanch]

nice pics

We use hydraulic vane pumps on all our eqiupment and the pumps fail now and then. Most of the time the cause is dirt that gets in the oil and scares the surfaces of the pump which hangs up vanes. we rebuild the pumps.

Someone talk about a pre lift pump filter it might be a thought if the pump is the part that fails.

later

mike

 

[TowPro]

Which Rev pump is doing these numbers? I just got a C version this spring on my 1998, its got about 6k miles on it so I have not checked it yet.

Originally posted by icarus33

With the latest rev. of pump, getting 14+ psi @ idle, 13 psi@ cruise, and 8 psi @ WOT.



ic

 

[icarus33]

The Cummins part # is 3990105 for the lift pump @ $139. 08 and the harness is # 4025182 @ $7. 13.



ic