Community Forums

dons2346 · 12-13-2016, 09:00 PM

Just to play the devil's advocate here.

The current lift pump runs for 30-40 seconds and then shuts off. With the Fass pump, I assume that power is supplied to it full time so what happens if and when something happens and there is no power to the Fass?

Woke up in the middle of the night with this possible problem and have been working on a fix such as some kind of indicator light to indicate power/pressure failure.

What say the experts?

jleamo1 · 12-14-2016, 06:43 AM

Quote:

Originally Posted by dons2346

Just to play the devil's advocate here.

The current lift pump runs for 30-40 seconds and then shuts off. With the Fass pump, I assume that power is supplied to it full time so what happens if and when something happens and there is no power to the Fass?

Woke up in the middle of the night with this possible problem and have been working on a fix such as some kind of indicator light to indicate power/pressure failure.

What say the experts?

Don, I took it to extreme and installed a fuel pressure gauge on the dash, my pump runs all the time. I am monitoring the fuel pressure after the last filter.

Old Scout · 12-14-2016, 07:21 AM

A couple years ago my lift pump was leaking so I was looking at replacement. I was told by my Cummins tech that the lift pump cycles during start up but runs continuously while the engine is running. However, they also diagnosed my leaking pump as a rear engine seal leak?????? Anyway, tightened the three bolts on the pump and it hasn't leaked since.
Sorry, I didn't read all 4 pages of this thread--but am curious, does the FASS pump go in line after the fuel filter--assume pump pulls fuel thru the filter from the tank vs pushing it thru--correct? Also, is there a good source for fuel pressure gauge?

TR4 · 12-14-2016, 10:13 AM

Quote:

Originally Posted by Old Scout

A couple years ago my lift pump was leaking so I was looking at replacement. I was told by my Cummins tech that the lift pump cycles during start up but runs continuously while the engine is running. However, they also diagnosed my leaking pump as a rear engine seal leak?????? Anyway, tightened the three bolts on the pump and it hasn't leaked since.
Sorry, I didn't read all 4 pages of this thread--but am curious, does the FASS pump go in line after the fuel filter--assume pump pulls fuel thru the filter from the tank vs pushing it thru--correct? Also, is there a good source for fuel pressure gauge?

From all the reading I've done, the lift pump only runs for approximately 30 seconds prior to starting. This is to prime the lines to the CAPS. Once you crank the motor, the gear pump in the CAPS starts pulling fuel through the lines to build pressure, then enters the accumulator to build the high pressure for injection. The gear pump does all the work.

Fuel flow....fuel tank > primary fuel filter > lift pump > secondary fuel filter > CAPS.

I installed this...ISSPRO EV2 Series Gauges at DieselManor between secondary fuel filter and CAPS.

If you have a leaking lift pump, you're are probably pulling air into the system. As Smitty has posted, these CAPS pump need fuel to lubricate and cool. Starve them and you'll shorten their life.

Bill

**CountryFit** · 12-14-2016, 10:21 AM

Quote:

Originally Posted by Old Scout

A couple years ago my lift pump was leaking so I was looking at replacement. I was told by my Cummins tech that the lift pump cycles during start up but runs continuously while the engine is running.

just to echo on this... initially i thought the same thing - the lift pump stops after xxx seconds. but a year ago i found it being different - while engine was running, the leak was still going (i believed the lift pump was running). of course after replacing the gasket, that was cured.

TR4 · 12-14-2016, 10:54 AM

Quote:

Originally Posted by CountryFit

just to echo on this... initially i thought the same thing - the lift pump stops after xxx seconds. but a year ago i found it being different - while engine was running, the leak was still going (i believed the lift pump was running). of course after replacing the gasket, that was cured.

This is interesting. I've spoken to three Cummins mechanics. They've all said the lift pump only runs to prime and no longer runs after the motor is running. I've also read this.....maybe I'm wrong. I don't know if these mechanics are all not familiar with these pumps and just wanted to give an answer.

Maybe we can get some of the experts on the forum to clarify this, I don't want to be giving out false information.

Bill

Roy1 · 12-14-2016, 12:18 PM

Trust me my lift pump only runs for less then thirty seconds then it goes silent. When you turn on your ignition key you can hear it running then it shuts off. Roy 2002 allure

Old Scout · 12-14-2016, 05:33 PM

Roy1--I don't have the answer but think your explanation is not conclusive. Agree, the lift pump will only run for 20-30 seconds, IF you don't start the engine. Are you sure it shuts off once your engine is running???

If this is in fact true and the lift pump only runs prior to starting engine, then the longer term damage to the CAPS would be caused by air leaking into the system [not fuel leaking out] and the resulting fuel starvation?????? Seems if fuel starvation is the issue, you would start to see something wrong with regard to engine performance or a "check engine" warning--yes/no?

Roy1 · 12-14-2016, 11:26 PM

I am by no means any kind of an expert on this subject but your last paragraph would describe what most folks that know more then I do have been saying is the on going problem along with lack of proper caps lubrication. Also consider the guys that have added a fuel gage at the fuel filters and found the gage shows positive pressure during the first 30 seconds then a negative pressure while the engine is running. This is what I would expect to be the case with the lift pump off and the injunction pump sucking fuel from the tank. Possibly your fuel delivery is set up differently ?

jleamo1 · 12-15-2016, 07:39 AM

There are two different designs, both called CAPS.
1, ISB and ISC (lower HP engine on the ISC) runs all the time, Bosch VP44 Injection pump. The VP44 while it can draw fuel it doesn't have a fuel pump internally like the big brother in the photo below does.
1, ISC (higher HP), ISL, ISM lift pump is only a primer, Cummins designed Fuel injection pump, not a Bosch pump. looks like this;

jleamo1 · 12-15-2016, 07:42 AM

I know someone is going to ask me where the HP cut off is, I have no idea. When I spoke to Cummins they only can identify specifics by engine serial number not by what cam with what HP/Torque ratings. I would have had to speak to an expert and as we all know those people are usually replaced by cheaper labor reading from a screen that have no idea what they are looking at

jleamo1 · 12-15-2016, 07:53 AM

Quote:

Originally Posted by Old Scout

A couple years ago my lift pump was leaking so I was looking at replacement. I was told by my Cummins tech that the lift pump cycles during start up but runs continuously while the engine is running. However, they also diagnosed my leaking pump as a rear engine seal leak?????? Anyway, tightened the three bolts on the pump and it hasn't leaked since.
Sorry, I didn't read all 4 pages of this thread--but am curious, does the FASS pump go in line after the fuel filter--assume pump pulls fuel thru the filter from the tank vs pushing it thru--correct? Also, is there a good source for fuel pressure gauge?

In most applications they are installed as a direct replacement in the existing spot, this is the system above with the VP44 Bosch pump application. If you installed the FASS pump on the other design where it shuts off you will most likely starve the Fuel injection pump as the FASS pumps do not have an internal bypass like the factory lift/primer pump. TR4, Smitty and Myself, our coaches were altered, our pumps now run all the time and were relocated so there is always a feed of fuel to the Fuel injection pump, the end goal is reliability.
When I spoke to Cummins they were surprised that their CAPS pump was capable of pulling fuel that distance through two filters, I was also told it was not designed to do so, it was engineered to do it on a truck where the distance was maybe 6'. I had 51' of fuel line and two filters that poor pump had to suck fuel through. Needless to say it did it, but as soon as a filter became slightly blocked it would buck and carry on.

Old Scout · 12-15-2016, 07:54 AM

Good input on pump types. So it is probably safe to say the lift pump on my ISL400, build in 2001, is a priming pump only? Apologize for being late to the conversation but if I understand correctly, a "leaking" lift pump may allow air into the injector pump once the engine is running. If the lift-pump is leaking, it needs to be fixed, eg, tighten the three manifold bolts, replace gasket, or replace pump. Guess the question is: if mine is a priming pump only on my ISL400, is the Fass pump model discussed above, still the right application for my engine config?

jleamo1 · 12-15-2016, 08:48 AM

Quote:

Originally Posted by Old Scout

Good input on pump types. So it is probably safe to say the lift pump on my ISL400, build in 2001, is a priming pump only? Apologize for being late to the conversation but if I understand correctly, a "leaking" lift pump may allow air into the injector pump once the engine is running. If the lift-pump is leaking, it needs to be fixed, eg, tighten the three manifold bolts, replace gasket, or replace pump. Guess the question is: if mine is a priming pump only on my ISL400, is the Fass pump model discussed above, still the right application for my engine config?

My coach has an ISL400, built in 2001 (engine). The pump listed above is the one I installed. You have a primer pump only, same as me if you have CAPS. Being a 2003 do you have CAPS or Common Rail? I know somewhere along those years is when the switch was made.