Cummins ISC 350 Loss of Power

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Cummins ISC 350 Loss of Power

November 24, 2019, 10:07:41 am

I've traveled to Tampa, FL and toward the end of the first day I experienced a loss of power. The engine runs fine, no black smoke, runs smooth, just no power. I changed the fuel filters and added a biocide to the tank, thinking maybe I had bad fuel. No change, and the filters were pretty clean, no algae. The scenario is this: if starting out from stop the engine runs as normal, after gaining speed to about 40 MPH the engine load % drops to 45% (per VmSpec). The engine will not increase past this output, turbo output stays around 9 or 10 PSI output. Other than no power engine runs great. If I back off the accelerator completely and coast for a few seconds and then try to accelerate, the engine runs fine and outputs as normal, anywhere from 80-100% output. It will only maintain that for a few seconds and then steadily drop back to 45% and stay there. I limped along the second day but really need a solution. VmSpec error of "fuel delivery pressure" and "controller #2". Any ideas? Also, I changed the coach batteries last week, would that have a part in any of this, maybe need to reset something on the engine computer? If not a simple fix anyone have any experience with repair shops in or near Tampa? I'm at Lazy Days RV. Thanks for reading.

Re: Cummins ISC 350 Loss of Power

Reply #1 – November 24, 2019, 10:18:09 am

Check the lift pump. They fail frequently.

Pierce

Re: Cummins ISC 350 Loss of Power

Reply #2 – November 24, 2019, 10:28:01 am

Don (Don & Tys) has been fighting fuel delivery/reduced power/check engine light problems with his coach for some time. I believe he has the same engine as yours? If he doesn't see this thread and jump in, you might PM him. He is a sharp guy and always ready to help others.

Cummins ISC CAPS intermittent stop engine light (long!)

Re: Cummins ISC 350 Loss of Power

Reply #3 – November 24, 2019, 10:40:11 am

Use a pressure gauge will tell you if have enough pressure. You could have a bad fuel line that closes up when you are using
a lot of fuel and when you ease off it opens up. A vacuum gauge put in front of the lift pump will tell you if that is your problem.

Re: Cummins ISC 350 Loss of Power

Reply #4 – November 24, 2019, 10:46:02 am

I have a pressure gauge installed on the discharge side of the secondary filter. Our Detroit's lift pump is before the secondary filter. If you have Roger's software, you can monitor while driving in real time. Saves a lot of $$ in shop time.

Pierce

Re: Cummins ISC 350 Loss of Power

Reply #5 – November 24, 2019, 11:04:57 am

I changed out the lift pump 3 years ago before any issues as just did not want the leaking seal on them because of low sulphur fuel. So, not sure if mine was getting ready to fail. I do not seem to have any air in fuel problem with old lines.
Don was at ours when he was having those problems and it finally seems to have been fixed by adding the Hass fuel pump inline and maybe even the new larger capacity fuel cooler, but he will chime in to add comments.
JohnH

Re: Cummins ISC 350 Loss of Power

Reply #6 – November 24, 2019, 11:09:55 am

Thanks for the replies, I was planning on replacing the fuel lines in January.

Re: Cummins ISC 350 Loss of Power

Reply #7 – November 24, 2019, 11:11:18 am

If the fuel lines are good (as in replaced), the gear pump part of the CAPS assembly may be getting weak and or there might be an air leak on the suction side. There is a short rubber hose with crimped fittings that goes from the engine mounted secondary filter. It is an OEM Cummins part. Impossible to tell without looking whether or not it is cracked because of the braided covering. The part is a "Fuel Supply Hose Part# 3944988"
You can go to the Cummins QuickServe online website and register your engine number for free and get illustrated parts break down pictures as well as the part numbers that go with your engine number. The part is around $60 from Cummins a few bucks cheaper on eBay. I am not saying that this will solve your problem, but this hose will be overlooked when the fuel lines have been changed out.
Cummins Fuel Filter Flex Hose 3944988 NOS | eBay
My symptoms were a bit different. You can read about it in Chuck's link. Ultimately, it is design issue in my mind, which I wrote about in the referenced thread. Putting in a full time HD FASS lift pump is what ultimately solved my problem.
Don

Re: Cummins ISC 350 Loss of Power

Reply #8 – November 24, 2019, 07:35:49 pm

Thank you all for your help. I think I will try to have someone run diagnostics and pressures since i'm 1000 miles from home. Does anyone know of a good service center in Tampa?

Re: Cummins ISC 350 Loss of Power

Reply #9 – November 24, 2019, 07:50:35 pm

Quote from: Gegabyte – November 24, 2019, 07:35:49 pm

Thank you all for your help. I think I will try to have someone run diagnostics and pressures since i'm 1000 miles from home. Does anyone know of a good service center in Tampa?

I have no personal knowledge but this recommendation for Tampa service was posted a while back:
RV Service in the Tampa Bay area?
Good Luck, Dave A

Re: Cummins ISC 350 Loss of Power

Reply #10 – November 24, 2019, 10:00:56 pm

Paul Yasbeck is a Foretravel mechanic expert who is 1-1/2 hour away from Tampa in Leesberg, FL. ...If you can make it there.

Re: Cummins ISC 350 Loss of Power

Reply #11 – November 25, 2019, 07:51:27 pm

I have had good luck with Cummins Coach Care facilities in finding and fixing my issues with my ISC350. I am not a tech but I can tell you that Cummins found a problem and fixed it - the accumulator section of my CAPS fuel pump. The other issue was fuel pressure solenoid and another part giving my ECM bad signals. Cummins built the engine and they know and understand them.
Not all Cummins facilities are Coach Care and some don't want to work on motorhomes.

Here is list of Coach Care facilities for Florida- looks like you are in luck with one in Tampa.

Florida
Jacksonvile, FL*
755 Picketville Rd. Jacksonville, FL 32220
904-378-1902
Ocala, FL**
321 S.W. 52nd Ave. Ocala, FL 34474
352-861-1122
Orlando, FL**
4820 N. Orange Blossom Trail Orlando, FL 32810
407-298-2080
Tampa, FL**
5910 E. Hillsboro Ave. Tampa, FL 33610
813-626-1101

If you are not a member of the Cummins Power Club join when you go to Coach Care- 10% off parts and labor for just a dues of $19.00- pays for itself first visit.

Best of luck getting back on the road............

Re: Cummins ISC 350 Loss of Power

Reply #12 – November 30, 2019, 09:37:51 am

Thanks everyone for your help, just to give an update. I did take the coach to the Tampa Cummins Coach Care facility here in Tampa, Paul Yasbeck said he was unable to work on the Cummins engine and suggested I take it there, very nice man by the way, he did try to troubleshoot on the phone. They changed the lift pump but that did not fix the problem. I have changed the lift pump and both fuel filters so far. They now say the CAP pump is bad and needs replaced. I asked about changing just the part that failed and they said that they have done that in the past only to have other parts fail shortly after and the customer incurring double the labor charge. They won't know until they remove the pump which part failed. The new pump should arrive Tuesday. So, in a holding pattern. I can't believe a pump costs this much! They also said I had a small leak at the charge air cooler, but not the significant reason for the loss of power. I'm getting 8-10 psi boost at 45% load and about double that when the engine does output as it should.

Re: Cummins ISC 350 Loss of Power

Reply #13 – November 30, 2019, 10:28:17 am

Bummer. Was hoping that it was not bad. Good bunch of posts here: bad years for cummins caps pump - Google Search Some owners have converted the engines to the Bosch P pump. It's also expensive for the new kit but used pumps can be found and they will outlast several engines.

Betting Cummins wants more than $8K before you drive away if they install a new pump. The rebuilt CAPS pumps have a bad reputation so you might read the posts about it. Poor pressure from the lift pump could cause CAPS failures.

Sorry to hear about the expensive problem.

Pierce

Re: Cummins ISC 350 Loss of Power

Reply #14 – November 30, 2019, 10:50:28 am

Mine was 5600.00 5 years ago, parts and labor.

Re: Cummins ISC 350 Loss of Power

Reply #15 – November 30, 2019, 01:16:17 pm

Spotted this: CAPS Cummins Injection Pump | Fuel Pump | Thoroughbred Diesel

Might be worth a call.
jk

Re: Cummins ISC 350 Loss of Power

Reply #16 – November 30, 2019, 02:29:21 pm

Quote from: kimosabe99 – November 30, 2019, 01:16:17 pm

Spotted this: CAPS Cummins Injection Pump | Fuel Pump | Thoroughbred Diesel
Might be worth a call.
jk

It's a remanufactured pump but has a one year warranty. It appears that all CAPS pumps advertised online are rebuilt/remanufactured.

P

Re: Cummins ISC 350 Loss of Power

Reply #17 – November 30, 2019, 03:12:14 pm

I have seen a handful of new old stock caps pumps on eBay, but none of the part numbers showed as being appropriate for our engine build number. I don't know what differences there are, butter foretavel ISC was the top rated horse power version and there were many others as low as 250 horse power or less, Sso that might explain it so that might explain it.
Don

Quote from: Pierce & Gaylie Stewart – November 30, 2019, 02:29:21 pm

It's a remanufactured pump but has a one year warranty. It appears that all CAPS pumps advertised online are rebuilt/remanufactured.

P

Re: Cummins ISC 350 Loss of Power

Reply #18 – December 01, 2019, 03:30:06 pm

I was quoted $6,000 in Arizona for the whole CAPS pump- fyi. Sorry you are having such an issue, but hopefully this will get it fixed once and for all.

Hope you get on the road soon.......................

Re: Cummins ISC 350 Loss of Power

Reply #19 – December 01, 2019, 03:57:15 pm

Thanks everyone. They quoted $6,200 plus the lift pump. I will let you know how it goes.

Re: Cummins ISC 350 Loss of Power

Reply #20 – December 01, 2019, 05:01:35 pm

New pump or remanufactured? Warrranty?

P

Re: Cummins ISC 350 Loss of Power

Reply #21 – December 01, 2019, 05:43:28 pm

New pump, 1 year warranty.

Re: Cummins ISC 350 Loss of Power

Reply #22 – December 02, 2019, 01:17:19 pm

I was told the pump had a 1 year/100,000 mile warranty. Once you get fixed up and lighten the load in your wallet time to hammer down and get your miles worth out of the repairs. That is a reasonable price since mine was quoted about 2 years ago.

Re: Cummins ISC 350 Loss of Power

Reply #23 – August 16, 2024, 11:35:12 am

It sounds like you're dealing with a frustrating issue, especially when you're on the road and relying on your vehicle's performance. Based on your description, it seems like the problem could be related to a few different areas, but here's a breakdown of potential causes and some steps you might take:

Potential Causes:
Fuel Delivery Issue: Given the "fuel delivery pressure" error, it seems like the engine isn't getting the fuel it needs at higher speeds or under load. Since you've already changed the fuel filters and added a biocide, the next step might be to check the fuel pump or fuel pressure regulator. There could be a restriction or a problem with the fuel pump that's causing the engine to limit power output.

Turbocharger Issue: The turbo output staying around 9 or 10 PSI is lower than expected when under load. This might suggest that the turbo isn't fully spooling up or that there's an issue with the boost control system. This could be related to the fuel delivery issue or might indicate a problem with the turbocharger itself or the sensors controlling it.

Electronic Control Module (ECM): The "controller #2" error could point to an issue with the ECM or a related sensor. Since you recently changed the coach batteries, it's possible that a reset or recalibration is needed. Sometimes, disconnecting the batteries for a few minutes and then reconnecting them can reset the ECM and resolve such issues.

Air Intake System: Although you didn't mention any issues with the air intake, it's worth checking to make sure there aren't any restrictions or blockages that could be limiting the engine's power output.

Next Steps:
Reset the ECM: Given that you changed the coach batteries recently, it might be worth trying a hard reset of the ECM. Disconnect the vehicle batteries for about 10-15 minutes, then reconnect them and see if the problem persists.

Check for Diagnostic Trouble Codes (DTCs): If you haven't already, use a diagnostic tool to check for any additional error codes that might give more insight into what's going on.

Visit a Cummins Service Center: Since you're near Tampa, you might consider taking the vehicle to a Cummins service center or a shop that specializes in Cummins engines. They can run more detailed diagnostics and check for any issues specific to the fuel system, turbo, or ECM.

Finding a Repair Shop:
Lazy Days RV is a well-known facility, but if you need a specialized Cummins service center, you might want to visit Cummins Sales and Service in Tampa. They have the tools and expertise to diagnose and repair issues with Cummins engines, including the Cummins ISC, and can likely get you back on the road with confidence.

Hopefully, this helps you narrow down the issue and find a solution quickly. Safe travels, and best of luck with the repairs!

Re: Cummins ISC 350 Loss of Power

Reply #24 – August 16, 2024, 12:54:22 pm

Note that Reply #23 (above) was added to a 5 year old thread.

The information in @advancediesel's post is certainly valuable and worth reading, especially if a Forum member was to encounter similar symptoms.

The OP's loss of power situation was apparently fixed by installing a new CAPS pump. I say apparently because the OP never came back and actually verified that the problem was totally resolved to their satisfaction.

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