Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > POWER TRAIN GARAGE FORUMS > Cummins Engines
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-19-2021, 04:52 PM   #1
Junior Member
 
Join Date: Jul 2021
Posts: 3
Bad running Cummins 8.3 caps

I have a 1999 American Dream Motor home with an 8.3 Cummins ISC caps Engine 133000 miles on it

And it is turning in to an American Nightmare.
Maybe somebody familiar with this Engine has some ideas.
Any help is appreciated.


Engine is loping/hunting on idle, black smoke runs bad and has weird noise coming from muffler. Had a few mechanics advise me what to do, but it not helps much. Did a lot of work and replace parts, but it is still doing it.

Here is what I did so far.

Replaced fuel filters, replaced fuel hoses from tank to filters. Drained the fuel tank replaced with fresh diesel, checked air filter, replaced Injectors. Installed Fass lift pump. Replaced high pressure pump with Cummins rebuilt, That made it smoke less, had Injectors that I replaced rechecked, removed timing gear cover checked timing marks, removed and checked Muffler and exhaust brake. Checked Turbo, spins freely, no oil leaks. Waste gate closed, Replaced Cam sensor and speed sensor. Replace map sensor, pressurized intake from turbo, no excessive leaks. Checked Valve adjustments numerous times does not change, checked compression 400/420.checked exhaust manifold no visible cracks



Check engine was on before I replaced the hp pump, but now no more check engine light.

One mechanic suspected that it was a slapping piston, but with good compression and no blow by, it seems unlikely to me.
Below is a link to the Video.

goldsky is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 07-19-2021, 05:00 PM   #2
Senior Member
 
Monaco Owners Club
Join Date: Jun 2010
Location: Willard .Missouri
Posts: 119
May have over look in the post has th the air to air system. Been checkFor leaks
oh no is offline   Reply With Quote
Old 07-19-2021, 05:03 PM   #3
Senior Member
 
mackwrench's Avatar
 
American Coach Owners Club
Join Date: Apr 2016
Location: North Florida
Posts: 2,027
Definitely sounds like it's missing.
I think fuel related. The fuel pressure gauge needle is jumping "in time" with engine miss. You replaced injectors and them rechecked them, how are you getting them checked?

Can you access top of engine with it running and crack each injection line one at a time to narrow down what cylinder is missing....


It seems to crank and start right up, so I'd not think it's pulling air into fuel system somewhere, but you can take a piece of clear hose and put inline before the lift pump and see if any air bubbles....
__________________
1999 American Eagle
ASE med/heavy certified technician
ASE advanced diesel certified
mackwrench is offline   Reply With Quote
Old 07-19-2021, 05:10 PM   #4
Senior Member
 
mackwrench's Avatar
 
American Coach Owners Club
Join Date: Apr 2016
Location: North Florida
Posts: 2,027
What is idle speed? If you use the high idle button on dash and raise it a bit does the fuel pressure gauge needle smooth out?

Also, I didn't see where you had air intake/filter checked....air intake no restrictions, filter ain't collapsed?

I'm just WAG ing....lol

EDIT- seen you checked filter, take off intake piping AFTER CAC and start it up....?
__________________
1999 American Eagle
ASE med/heavy certified technician
ASE advanced diesel certified
mackwrench is offline   Reply With Quote
Old 07-19-2021, 07:00 PM   #5
Senior Member
 
mackwrench's Avatar
 
American Coach Owners Club
Join Date: Apr 2016
Location: North Florida
Posts: 2,027
Have you got a scan tool, or basic code reader that'll give you live data? Talking to a buddy of mine tells me the throttle position sensor could be issue...older coach version used a single reference sensor that could be sending erratic voltage to ecm...

A live data reader should let you see TPS voltage in and out, or minimum percentage of throttle at idle/wot
__________________
1999 American Eagle
ASE med/heavy certified technician
ASE advanced diesel certified
mackwrench is offline   Reply With Quote
Old 07-20-2021, 11:38 AM   #6
Senior Member
 
Join Date: Jul 2018
Posts: 158
Bad running Cummins 8.3 caps

Iím also assuming you havenít had INSITE Hooked up to the Ecm to check data. Personally if I didnít have live data to check I would start by unplugging sensors one by one and see what happens. It will run with pretty much all of them unplugged and go to a default value for that sensor. Many of the sensors are on common returns to the Ecm and really strange things can happen. I would also check for a plugged fuel return line.
randomledder is offline   Reply With Quote
Old 07-20-2021, 12:46 PM   #7
Senior Member
 
mackwrench's Avatar
 
American Coach Owners Club
Join Date: Apr 2016
Location: North Florida
Posts: 2,027
Quote:
Originally Posted by randomledder View Post
Iím also assuming you havenít had INSITE Hooked up to the Ecm to check data. Personally if I didnít have live data to check I would start by unplugging sensors one by one and see what happens. It will run with pretty much all of them unplugged and go to a default value for that sensor. Many of the sensors are on common returns to the Ecm and really strange things can happen. I would also check for a plugged fuel return line.
This.

Even most of the basic of code reader will supply live data. I've got this one from Amazon, I keep in coach.
Comes with J1708 connection and HD/OBD. It ain't no insite or anything fancy, but will get all the live data, read/clear codes.

Hopefully OP will update here and not just one post and done!Click image for larger version

Name:	Screenshot_20210720-144350.jpg
Views:	6
Size:	48.5 KB
ID:	336646
__________________
1999 American Eagle
ASE med/heavy certified technician
ASE advanced diesel certified
mackwrench is offline   Reply With Quote
Old 07-20-2021, 08:01 PM   #8
TR4
Senior Member
 
TR4's Avatar
 
Join Date: May 2016
Location: San Francisco Bay Area, California
Posts: 806
I had an engine, not diesel, that broke a lifter. The lifter took out the cam. Had normal compression but missed. A dial indicator on valves will eliminate this as a possibility.

Bill
__________________
2003 Country Coach Intrigue 36'
Cummins ISL 400
TR4 is offline   Reply With Quote
Old 07-22-2021, 12:29 AM   #9
Junior Member
 
Join Date: Jul 2021
Posts: 3
Update American Dream

Here is an update from the American Dream Motor home. First, I would like to thank all who replied.
The Injectors I had rechecked at the place I got the HP pump.
I cracked the injectors lines one by one, and they all acted the same.
Then I placed a clear hose between the hose from the tank to the fass lift pump. Turned on the ignition, engine not running and no air in clear hose.
However, the clear hose wanted to collapse, and the fuel gauge was jumping like in the video.
Then I took a container with Diesel behind the Motor home, put a hose from the container to the fass pump and the return line from the fass pump back in the container turned on ignition and had a steady fuel gauge.
Start engine still runs bad.
Took the injector line loose from cyl 6 placed a clear hose on it and placed it in a bucket started the Engine ran it for about 30 sec and had a constant flow of air bubbles.
I don't think that should do that. I don't know where it could suck the air in, but I will check the fuel filter and housing that mounts on the engine and the hose from the filter to HP Pump.


I also ran the engine without air filter and no difference.
I do have one of those obd checkers from Amazon, but it never gave me a code even when the Protect Engine light was on before.
It may take a few days before I get back to it, but I will post any results.
goldsky is offline   Reply With Quote
Old 07-22-2021, 08:51 AM   #10
Senior Member
 
Ljwt330's Avatar
 
Join Date: Jan 2018
Location: Capistrano Beach, California
Posts: 3,709
Quote:
Originally Posted by goldsky View Post
Here is an update from the American Dream Motor home. First, I would like to thank all who replied.
The Injectors I had rechecked at the place I got the HP pump.
I cracked the injectors lines one by one, and they all acted the same.
Then I placed a clear hose between the hose from the tank to the fass lift pump. Turned on the ignition, engine not running and no air in clear hose.
However, the clear hose wanted to collapse, and the fuel gauge was jumping like in the video.
Then I took a container with Diesel behind the Motor home, put a hose from the container to the fass pump and the return line from the fass pump back in the container turned on ignition and had a steady fuel gauge.
Start engine still runs bad.
Took the injector line loose from cyl 6 placed a clear hose on it and placed it in a bucket started the Engine ran it for about 30 sec and had a constant flow of air bubbles.
I don't think that should do that. I don't know where it could suck the air in, but I will check the fuel filter and housing that mounts on the engine and the hose from the filter to HP Pump.


I also ran the engine without air filter and no difference.
I do have one of those obd checkers from Amazon, but it never gave me a code even when the Protect Engine light was on before.
It may take a few days before I get back to it, but I will post any results.

My thoughts.


Note bold.


When the line into the lift pump wanted to collapse, that indicates a blockage from the tank, IMO. That same line, when placed into a container of diesel, along with the return line, showed a good, solid flow. The only change between the two flow characteristics through the FASS pump was the source of the diesel--the tank.


Such a clog would cause cavitation within the lift pump, producing bubbles which you witnessed at the injector rail. You might try removing the fuel cap and see if there is an improvement. It's possible that somehow the venting of the tank has been compromised. If there is no change, it seems something is blocking free flow of fuel out of the tank port.
__________________
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.
Ljwt330 is offline   Reply With Quote
Old 07-22-2021, 10:43 AM   #11
Senior Member
 
Join Date: Oct 2020
Posts: 404
Quote:
Originally Posted by Ljwt330 View Post
Such a clog would cause cavitation within the lift pump, producing bubbles which you witnessed at the injector rail. You might try removing the fuel cap and see if there is an improvement. It's possible that somehow the venting of the tank has been compromised. If there is no change, it seems something is blocking free flow of fuel out of the tank port.
To piggyback on this -- you could take your gas cap off and blow compressed air through the line towards the tank. Not sure if there is a check valve there but would be possible to dislodge anything that might be hung up at the pick-up point?
__________________
2000 Monaco Diplomat 38D
Fffrank is offline   Reply With Quote
Old 07-22-2021, 10:50 AM   #12
Senior Member
 
Join Date: Oct 2014
Posts: 2,920
Actually sounds like two separate issues:


Restriction on the suction side allowing hose to collapse (tank to lift pump or aftermarket pump if installed).


Air leak into fuel system. Yes, filters are the first place to check.


Restriction WILL make any air leak much worse as the lines and primary filter located before the fuel pump are under higher vacuum.


Both need to be addressed or CAPS failure is just around the corner.
__________________
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
wolfe10 is offline   Reply With Quote
Old 07-22-2021, 12:47 PM   #13
Senior Member
 
mackwrench's Avatar
 
American Coach Owners Club
Join Date: Apr 2016
Location: North Florida
Posts: 2,027
I'm with wolf, could be the pickup line from tank is yuked up....

The fact that fuel pressure gauge needle smooth out is a red flag.


Was OEM lift pump bypass when you installed FASS pump?

The code reader you have able to see live data?


BTW..... I'm digging the old Econoline pickup in your other video!
__________________
1999 American Eagle
ASE med/heavy certified technician
ASE advanced diesel certified
mackwrench is offline   Reply With Quote
Old 07-25-2021, 10:07 AM   #14
Junior Member
 
BTux's Avatar
 
Monaco Owners Club
Join Date: Apr 2012
Posts: 13
Just a thought... I was out 3K with similar issues. Cummins mechanic finally found a faulty ground wire to the ECM on the negative post of the cranking batteries. In the ringlet crimp area, under a wing nut instead of a normal fastener. Installed a much better connection to the ground wire, tightened all posts to a specific torque value and I am good. If ... the ECM does not have good clean power source, all kinds of things show up... I averaged 6 MPG before repair... Average now is 8.5 MPG... Crazy??? But true.
BTux is offline   Reply With Quote
Reply

Tags
cummins



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Good SAM...Bad Sam Bad Bad Bad! STLNLUV iRV2.com General Discussion 43 12-17-2018 07:49 AM
CAPS Fuel Pump Bad 1999 Cummins 8.3L ISC pinacocacola Cummins Engines 4 04-20-2016 09:26 PM
Bad, bad, bad - bad vibrations.... Doc Vegas Ford Motorhome Chassis Forum 21 11-30-2014 05:56 PM
Vectra/Cummins coolant reservoir caps RKL2 Winnebago Industries Owner's Forum 4 04-12-2008 08:07 AM


All times are GMT -6. The time now is 03:30 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.