DickandLois

Cummins ISL And ISC Engines With CAPS Fuel Injector

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Beginning in 1998, Cummins introduced the ISC based off the earlier mechanical 8.3 C-series engine. The original ISC engine featured a Cummins Accumulator Pump System (CAPS).

This CAPS pump was a computer controlled injection pump,with individual fuel lines to each injector.

In 2003 the HPCR system was introduced.

Cummins Accumulator Pump System (CAPS) fuel injection pump for Cummins 6 cylinder C series engines where used in heavy duty on-road, agricultural applications and many Motor-home applications.

Cummins ISC 8.3 300 Hp Warm engine rough Idle

Some time ago Cummins issued a service bulletin to change the wiring from the old connector and lead that goes to the fuel pressure sensor to a new connector and lead - an upgrade kit was issued for this which included a new connector, three crimp connectors and an instruction sheet.

A lot of time the connectors which are supposed to be sealed upon crimping, fail and the ECM sees the fuel pressure vary during idle hence rough idle and sometimes no starts.

The solution is twofold, one is to clean and inspect every connector (including the big one near the lift pump) and degrease/grease them with the right dielectric grease made for Packard connectors (a lot of techs fail to get that part).

The second is if the upgrade was done, have the tech properly splice (re-solder) the connection and use the correct method to seal the splice.

Also, check the Transient Suppressor. A bad one can damage the injector pump, and if you change the injector pump with out replacing the suppressor; will void the warranty.

Not always the problem, but worth a try!

Replacing the injectors will not solve a bad injector pump problem.

One brand new injector bad?

As the engine warmed up the O-ring on the injector expanded out of spec. and was failing.
To be sure that was the problem, moved the injector to different cylinders to see if the problem followed and it did, but the injector pump proved to be defective also! A relatively new injector pump about 6 months old and exchanged under warranty.

Internal seal-diaphragm can fail and fuel will pass into the oil, making oil! Not good!

Fuel Pressure Specs ISC Series (Minimum)

Low Fuel flow / Pressure can damage the internal electronics. The excess fuel is used to cool the circuits and then returned to the fuel tank.

HPCR CAPS

Lift Pump 5 psi Cranking 5 psi Minimum

Gear Pump 10 psi Cranking 10 psi Cranking

70 psi @ rated speed

Rich.

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Jack,

No! Your year engine is equipped with a HPCR(High Pressure Common Rail)system that is controlled by the ECM. The electrical coils in the injectors are pulsed from the ECM.

Rich.

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jleamont   

Did Cummins correct any of this on line prior to releasing later engines? I have a 2001 ISL400 I just replaced the lift pump and all suction fuel lines, I am familliar with the connector you spoke of (big round twist connect with multi pins) under lift pump. Usually the first one-two years out on a new product are the problem units and as time goes on service bulletins get corrected on the production line as redesigned parts become available.

Does the message above have a serial number range, production date range?

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jleamont,

Good question!

In all the reading I have done, I have not seen any information listing the years or serial numbers relative to the problem.

Makes me think that there are remaining issues, because the C and L series engines up to 2003 still suffer problems in the same areas.

Rich.

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Beginning in 1998, Cummins introduced the ISC based off the earlier mechanical 8.3 C-series engine. The original ISC engine featured a Cummins Accumulator Pump System (CAPS).

This CAPS pump was a computer controlled injection pump,with individual fuel lines to each injector.

In 2003 the HPCR system was introduced.

Cummins Accumulator Pump System (CAPS) fuel injection pump for Cummins 6 cylinder C series engines where used in heavy duty on-road, agricultural applications and many Motor-home applications.

Cummins ISC 8.3 300 Hp Warm engine rough Idle

Some time ago Cummins issued a service bulletin to change the wiring from the old connector and lead that goes to the fuel pressure sensor to a new connector and lead - an upgrade kit was issued for this which included a new connector, three crimp connectors and an instruction sheet.

A lot of time the connectors which are supposed to be sealed upon crimping, fail and the ECM sees the fuel pressure vary during idle hence rough idle and sometimes no starts.

The solution is twofold, one is to clean and inspect every connector (including the big one near the lift pump) and degrease/grease them with the right dielectric grease made for Packard connectors (a lot of techs fail to get that part).

The second is if the upgrade was done, have the tech properly splice (re-solder) the connection and use the correct method to seal the splice.

Also, check the Transient Suppressor. A bad one can damage the injector pump, and if you change the injector pump with out replacing the suppressor; will void the warranty.

Not always the problem, but worth a try!

Replacing the injectors will not solve a bad injector pump problem.

One brand new injector bad?

As the engine warmed up the O-ring on the injector expanded out of spec. and was failing.

To be sure that was the problem, moved the injector to different cylinders to see if the problem followed and it did, but the injector pump proved to be defective also! A relatively new injector pump about 6 months old and exchanged under warranty.

Internal seal-diaphragm can fail and fuel will pass into the oil, making oil! Not good!

Fuel Pressure Specs ISC Series (Minimum)

Low Fuel flow / Pressure can damage the internal electronics. The excess fuel is used to cool the circuits and then returned to the fuel tank.

HPCR CAPS

Lift Pump 5 psi Cranking 5 psi Minimum

Gear Pump 10 psi Cranking 10 psi Cranking

70 psi @ rated speed

Rich.

I just went to school again, I think ?

Has anyone run into this and if so that would explain the low power issues posted by Chuck in his thread No acceleration from dead stop and it might also cause the ISL and ISC engines with the CAPS fuel injector system to shut down after a few seconds posted by jleamont. Although he replaced the fuel supply and return lines and that appears to have solved the problem.

Cummins ISL, Runs For 30 Sec Then Stalls

Leads me to think that not only do you need to consider the lift pump, but also the injector pump on the ISC and ISL engines built from 1998 to 2003 and the 2003 ISB engine.

NOTE!

The lift pumps on these engines only run for a minute or so at start up, then they go into bypass and a gear pump on the injection pump sucks the fuel needed.

Rich.

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Might my problem be caused by the same issues?

My problem:

Had a problem last fall in my motorhome on parkway at 65mph.  After few miles, engine started cutting out.  When I let off accelerator engine would run okay until next demand like climbing or any heavy acceleration.  Got worse and worse over the next 200+ miles until barely maintaining 55 on flat.  (Injection believed to have been upgraded to HPCR in 2006.)

Shop installed Cummins remanufactured fuel pump on my ISC-8? (R460-AA2-001 SERIAL 45772889). Problem seemed resolved but didn’t put more than 25 miles on coach (running fine).  Unit sat for 3 months in storage in cold, one day subzero.  Would not start.  Waited ‘til spring for warmer day.  Mobile technician found no flow to fuel pump - replaced both fuel filters and got good flow but was airbound.  Purged air and engine would run fine at 1500 rpm about 4-5 mins then shut off like key turned off.  This keeps repeating – purge air, engine runs fine few mins then shuts down.

Any help appreciated.

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jleamont   

winbarrows, I had the a similar problem with my coach just after we purchased it. I also replaced the fuel pump on the engine first (was told to upgrade it by Cummins) and mine would run for 30 seconds and stall, with the primary fuel filter half full. Mine turned out to be the fuel lines deteriorated between the tank and the primary filter, I was pulling air up the line. What year, make model is your coach? 

If you remove the fuel line between the tank and the primary filter, put a fuel can under the coach and run a hose into it (pulling fuel from the jug rather than the coach fuel tank). Prime the filter and run the engine, if it doesn't stall now you have isolated the line between the tank (or a problem with the fuel pick up in the tank) as the problem. I made the mistake of not priming the filter when I did my test and it still stalled, prefill your filter with clean fuel first.

Can you see if you have rubber fuel lines or plastic tubing?

link;

 

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jleamont   

winnbarrows,

One thing I just remembered, when I would turn on my ignition, I could hear the pump buzzing in the rear, which was new, before I had not noticed that. That was the sign it was starving for fuel, unfortunately I heard it and ignored it, we had only had owned the coach for a month at this point, I just thought I didn't notice it before, since I had a problem I was more sensitive.

The dealer wanted $4000.00 to replace them, it took me 3 hours and cost me $600.00 in materials. Plus the tow to the Cummins dealer was an additional $1000.00

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jleamont   

Well, my CAPS pump is dying or that's what it feels like anyway. After 100 miles the coach began to buck violently when pulling away from a stop intermittently, only seems to happen on occasion under a heavier load, no engine fault codes yet but is suspect they will happen on the return trip home. we got to the CG but I am wondering how the trip home will go. When it's not bucking it runs as it always has. More to come.

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Joe, 

Had same problem with my 400 ISL. Turned out to be filters. Changed out both and added both conditioner and biocide. Seem to solve the issue. I will add conditioner ever second or third fill up more, often when at staions we aren't familiar with.

Herman 

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jleamont   

Herman, what the heck I'll give that a shot. I carry doubles of each. Strangely it didn't lack power just bucked, spit and kicked and I took off.

Thanks

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Joe, 

I could track my bad fuel to a staions where I filled up about 10 miles from home. Parked coach and didn't run the coach for about 3 or 4 weeks. Next time out I had the same issue as you described.That was when I changed the filters and added the chemicals. 

Haven't stopped there since nor had a problem since. 

Good luck with yours.

Herman 

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1 hour ago, jleamont said:

Both changed, tomorrow will tell. 

 

Do you have a gage so you can check the lift pump pressure?  I know you changed it but it would eliminate one possibility.

Bill

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jleamont   

Herman, thanks tomorrow will be the test.

Bill, no gauge here, sitting at a campground in Bethany Beach Delaware. The lift pump sounds fine key on engine off and once it starts the CAPS pump takes over and the lift pump shuts off. 

When I pulled the primary filter there was what looked like lawn grass (just two little pieces) next to the O ring. Which had me scratching my head. Both filters have maybe 2500 miles on them but as you both know it only takes one tank top off of garbage fuel to create a problem. I did run it low on the last trip, could be some crud in the tank that got pulled into the filters. Love to know where lawn clippings came from. 

I really do not feel like tossing a $3500 pump in this coach. I will post tomorrow on how it acted.

thanks guys!

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Joe, Do Not forget that there could be a bad fuel line. I did not read the entirety of your posts, so maybe you have replaced them or a bad section. Old rubber lines do get soft and mushy on the Inside. A blade of grass-One has to wounder if someone was mowing the grass next to the tanker and some clippings got blown into the drop lines. 

Rich.   

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jleamont   

Rich, I replaced all of the fuel lines in July of 2014 when the line failed between the tank and the primary filter, I pulled a Rambo and replaced all rubber lines at that time and the lift pump. Something that dawned on me last night, up in the NE we have winter blends of diesel, those blends will strip and clean the inside of the fuel tank resulting in more junk headed to the filters. I hadn't given it much though before but this coach would have had a few tanks of it in the end of last season and the beginning of this season. It causes problems at work with filters only lasting a short time since I don't actually fill this in winter it is still in the tanks from October through March and there will be residual into April and May.

these lines were the reason I thought the pump went bad from it starving for fuel so often two years ago, that couldn't have been good for it.

good thing my filters are right out in the open.

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Joe,

Yes, lucky your filter are right out in the open. When you have "Junk in the Trunk":o is may take more then one change out. Did you see anything other then the grass clipping you saw in or on the top of the filter? If you still have your old filters why don't you cut them open and just see what may have been filtered out. I would be like the curious cat,:unsure: I would have to look.

Let us know.

Herman 

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jleamont   

Got home 2hrs ago no issues at all. I cut the primary filter open and it had the same crud we get in tractors at work, it looks like cold bacon grease sludge, common up here but only in the winter. But the trip home didn't end without something acting up. My ABS light was flickering like a strobe light and flashed out a 17, 19 and 6 code, or that was what it looked like anyway.

Rich, do you have a code list for these?

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jleamont   

Bill, my lift pump is producing a little over 7 psi (mechanical gauge) . I have no way to test flow but i can tell you it's like a garden hose :o

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6 minutes ago, jleamont said:

Bill, my lift pump is producing a little over 7 psi (mechanical gauge) . I have no way to test flow but i can tell you it's like a garden hose :o

Joe, Rich hear. The pressure is within specifications for the lift pump. That tends to lead my thoughts to a bad fuel line, that in limiting fuel flow when the CAPS pump tries to increase the required flow rate.

Test - You can use a short section of fuel line running from the lift pump to a small can of Diesel. If things work normally - I would sure expect a bad fuel line !!!!!

Rich. 

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jleamont   

I will say I have never had a fuel filter as the end result for a bucking compliant. They were always lack of power, must be something with the CAPS design.

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