I am having a big problem with the lack of power from my C8.3. There are several things I have noticed.
When pulling away from a stop light I may have to travel a block to a block and half before it will go fast enough to shift into 2nd.
When going up some hills between NAC and I-20 it would lose power and get down to 30 mph.
When I did make it to I-20 it was still doing this, get to 50 mph going downhill but going uphill down to 30.
Then all of a sudden after a hard down shift it took off and ran like it should holding 65 up and down hill but that only lasted about 25 miles.
Sometime it felt like it was chugging while slowing down with it floored, other times it felt like that throttle was just not opening the throttle body and I was trying to drive 30 mph but I was standing one .
My volt meter was showing 12.2 volts but when I compared it today to my amp meter it showed the gauge being a little over 1 volt low.
It does have new filters, fuel lines and 50 gallons of fresh fuel. As you can see from the picture the bowl does not have any sediment in it.
I had it floored most of the time and my leg is still sore from Friday.
(https://photos.smugmug.com/Foretravel/Forums-post/i-x6M5w7B/0/5ace2107/L/20180121_143203-L.jpg)
Fuel delivery woes have been experienced by many of us. Some have created a detailed attack to address this problem. Sounds like you have considered filters. Is the Fuel Shutoff Valve behaving? That is, is it opening fully? Is the Lift Pump working? Lots to consider. You will have a much better understanding of the fuel system by the time you fix this. Good luck.
Some things to check: the fuel shutoff valve on the engine may not be all the way open, It's pulled open by a solenoid when the key is turned to start and then held open with the key in run. If you turn the key to run and pull it up it should latch and hold. More than likely though you may have a leak in the fuel supply line allowing air to get into the fuel line. The filter in the picture looks damaged, maybe an air leak there?? I have had the same thing happen to me in the past and I never was able to determine the cause. Always happened when going up and down moderate hills. Has me wondering if maybe the turbo exhaust gate was sticking open as without any boost the engine does not have much power. I would pull over and check things, find nothing wrong and the problem would magically disappear. If it ever happens again, I intend to look at the rod that opens the waste gate before I shut off the engine, as it may only stick open when hot.
Also turn on the key and have some one step on the accelerator and verify that the throttle is pulled all the way open. And make sure that nothing is under the pedal.
Thanks Lewis I will look at these items and check them out.
Thanks Jerry I will look the fuel shutoff vavle and see if it is operating correctly. I had this problem when I bought the coach in Houston and drove it straight to FOT and while they were fixing the bulkhead I had them replace the fuel lines and the filters. I will give them a call today and ask them what happened to that filter.
I had wondered if it might be something with the turbo, I will have to go look that one up to see about the operation of the dump valve. The throttle is a possibility that is why I asked in my other thread about the leak down as the step cover does not have the power to open and close on its own without a tug on it.
You definitely have
something that is causing low power output. You'll just have to slowly work through the possibilities.
I
hope that volt meter reading you mentioned (12.2) was when parked with the engine off. You should be seeing around 14 volts on your dash volt meter with the engine running. Low voltage while running can cause all kinds of strange problems. 12.2 is pretty low even when parked. A fully charged battery bank should be around 12.6 volts at rest.
Having a "sore leg" after your first drive in the coach is not unheard of. I suffered the same soreness. If you have only driven cars and pickup trucks all your life (like me), jumping into a diesel motorhome is a whole different deal. The position of the throttle pedal puts your leg and foot at a strange angle, and it takes a lot more force to hold the pedal down. I quickly discovered the "magic" solution: cruise control! Now I automatically get the cruise control engaged asap.
Do you know what kind of throttle system is fitted on your coach? You might have a "air throttle", or you might have a electronic throttle. This will make a big difference in how we diagnose your low power problem.
Diesel engines only need two things to run: air and fuel. Some "fuel" items to check have already been mentioned. You should also verify that the engine is getting sufficient air. Is the air filter fresh?
The C8.3 is a wonderful engine, and provides more than adequate power, when running correctly. Keep at it - we'll figure out the answer!
Thanks Chuck, with the gauge showing 12.2 but the batteries at rest were at 13.3 I then checked a light in the bathroom and it was 13.1, this how I determined that my gauge is off a bit.
The sore leg was from my 200 mile trip home jamming the pedal on the floor most of the way home. :o
The throttle system is an air system.
The sensor on the air cleaner shows it OK but I will pull it out and give it a visual.
The strange part was that for a bit it ran great so I have to believe it is something interminet?
This not likely...but i lost turbo air, some, due to a leak of air. Normal hill climb quite impactedbut not notice other you noting.
On mine i was new to it, called MOT and they said sounded like lost some boost. first to check is clamp that hold air line on turbo...and it was a bit loose. Tightened and solved.
I doubt very much this related to your situation and others have given you ideas better.
Did you say this behavior was also when first bought it, before you hadit in the shop? If it is not the fuel shut valve, and this not a new after the shop visit, were they told to look into these symptoms? Reason to think on these is that the cause may be simply related to work they did, thus easier to narrow the cause.....which could be what...fuel line, filters? But I know you already thought thru that.
Let us know what you find, always am learning.
Change BOTH fuel filters-- always the first thing when experiencing loss of power with a diesel engine.
And, the dash voltmeter is for the chassis batteries.
Bathroom and other locations are connected to the HOUSE batteries.
Common to have some voltage loss between chassis batteries and dash gauge, but a full volt is a lot. Check connections for tightness and corrosion.
Having the Bendix air throttle/cruise control introduces a whole 'nother set of variables. You will need to familiarize yourself with that system, so you can check to see if your low power problem is originating there. The two threads below will be a good primer.
Be sure to follow all the included links to other info resources.
air throttle problem (http://www.foreforums.com/index.php?topic=32628)
Accelerator pedal air leak ??? (http://www.foreforums.com/index.php?topic=26936).
Yes I had them change both of them plus the one on the Gen.
I have checked the terminals for tight and there is no corrosion. Can I unplug the voltmeter on the dash and use my tester in the plugs?
Thanks
Thank for the links Chuck I will mine through them ^.^d
Looking at the picture, looks like the primary fuel filter is partly crushed.
If it is enough to slightly deform the gasket area, you could have a vacuum leak sucking air into the fuel system.
Was the coach power OK before the service work?
The fresh fuel could be the culprit. Like Brett posted, change both filters. How did the primary filter get the big dent? Check engine battery voltage at the batteries with digital voltmeter. You could compare voltage between battery and ignition solenoid and check security of wires/connection at the solenoid while you are there. Does it crank and start normally? Other possibilities are lift pump but I'm betting filters.
Pierce
I sent NAC a picture of it to see what they say about it being crushed like that.
No it was poor when I left Houston
What I asked early on....if it doing this before service, suppose you told shop, so what did they say was cause? Fuel lines???
Thanks Pierce, Not sure how the filter got bent, I sent FOT a email with the picture and asked what happened as they just installed all three filters before I picked up the coach so they had 0 miles on then when I left.
The coach starts up fine, turn on the key, wait for the gauges to do their thing and give it a twist and it fires right up and idles smooth.
Dear Super..,,let's talk low fuel level. If after yuh added 50 not enough added to start generator makes me wonder if sucked some trash up into a filter? Just amateur question I am asking!
Thanks Mike, that is why it took the picture of the filter with the sediment bowl, you have see the plastic plug all the way to the bottom. I think the fuel my be a little dark but I am not sure if the bowl is clear or if it is tinted?
Hesitate to respond as many know how fijters with better than me, but for you and me.....maybe small stuff not sediment plugs up filter medium?
Your throttle being air is interesting. My build is 5081 and they had moved to the King system. When you next lift the bed look at the forward passenger side of the compartment. If there is a silver box with a cable to the throttle you have a King system which for want of a better term is a hybrid. Mechanical and electrical.
If it is this system, go to the forward drivers side and open the compartment and look to your left. You will see two switches. Clean the terminals. With these not making proper contact you will be limited to 1/3 power.
Good startup/smooth idle but then lack of power is almost always a sign of poor fuel delivery. Usually related to filter issues. Many times, the coach will start fine and at low throttle loading, run fine. Nice and smooth on the slightly downhill parts, but soon after starting up an incline, it will lose power. Air in the system usually makes starting hard.
If you have an electronic engine, one of the computer or tablet readers/apps may show fuel pressure. Our DDEC does than but I'm not that familiar with Cummins electronics.
No shop should install a filter with a huge dent like yours has. Not many ways a road gator could do that.
Pierce
Did I miss something about the generator not starting?
To answer the other part of your question Mike, I had less that 1/4 tank when I got to FOT and then after I left there I added the 50 gallons, Gen starts and runs fine now.
Good info George, here is a picture of the throttle cable, can you tell from this?
(https://photos.smugmug.com/Foretravel/Forums-post/i-rH59j2g/0/bb9d7471/L/20180120_140024-L.jpg)
From this picture yes it is now take a look forward.
OK, thanks George, I will do that this afternoon.
I posted on this a few months ago but can't find the link. I replaced both switches and the relay. Napa carries the parts. No further problems. You may have the manual as an addendum in your main manual. They were sold to Cruise King and are great customer service folk.
Is this it?
Intermittent power 97 270 KC2600 not fuel (http://www.foreforums.com/index.php?topic=32410.0)
You are so good! Yup that's it. Thank you.
SO, Super8, if you actually have the King throttle system, you can forget about reading the Bendix material. No need to clutter up your brain with unnecessary data. 8)
Huh??? what day is this, where am I "LOL"
Thanks ^.^d
Thanks George, OK, now where might I find that 20/30 amp relay in the last picture?
Did you just clean the two switches or replace them?
One of the head scratchers I have with the plethora of paperwork I have is a lot of it was not removed when a different item was installed! :headwall:
Mike,
You have Bendix air throttle and King Control Cruise. That is the best/most reliable set up.
Napa has those as well but they are common. I replaced the brake switches. CAUTION you need to bleed the air first. It is my understanding they don't fail often but I preferred replacement. They are in the heavy equipment stock. Search the Forum under brake switch for their part number.
Foretravel had problems with the King Control, sometime in 1995 -1998 they came up with a kit to change the electronic throttle to an air throttle, it came with a new foot pedal, air cylinder and new throttle cable and brackets, this eliminated the king control as the throttle, but it retained it for the cruise control, if you think you have the air throttle check the foot pedal for three air lines, this will help diagnose your problem.
We had a similar problem in Colorado about two years ago. We didn't think that the filters were clogged but replaced them anyway. That did not help so we took it to a truck shop. It took them a long time to figure out what was wrong. The primary (water separator) filter mount has entrance and exit canals for the fuel to flow into and out of the filter. The exit canal is open but the entrance canal has about a dozen or so small holes designed to keep debris out. Most of these holes were blocked with what appeared to be rubber bits. The mechanic replaced the mount with another one which solved the problem and we were able to complete our trip. We had MOT check the fuel line but they couldn't see anything wrong with it. I'm guessing we got some hose debris from a fuel pump.
Thanks for the info Rob.
Well FOT is going to send me a new filter and the tech said that the King System needed to be replaced with the air system.
I will have the switches tomorrow so I will get them in and see what happens first. Are their any tools besides end wrenches and nut drivers needed to replace these?
If you need help diagnosing the King Control, Steve is excellent. Have not contacted him in a couple of years, but try this contact information:
King Control. Steve Boler. 22250 Glyview Trail, Faribault MN 55021, 507-334-0250 try 952 944-9644 FIRST. Steve@cruisecontrolking.com. Semi Truck, Bus, RV, Service Vehicle Cruise Control Installation (http://www.cruisecontrolking.com)
And, agree the combination of air throttle and King Control cruise is an excellent way to go. But, to get it going, after fuel filters, or at least replace the damaged primary and cut it open to see if it is contaminated), you might troubleshoot the King unit with Steve.
Thanks for the contact info Brett.
I had asked FOT to keep the old filters for be but that didn't pan out but I will cut this one up and see if I see anything after 239 miles and over 5 hours driving time.
Others have mentioned the fuel solenoid. It is located on right side forward of injector pump as looking in from rear. Pull up on plunger fully, cable tie it in up position. If this fixes the low power, just drive that way until you can get it fixed. Tie it up before starting and cut the tie to let it fall down to stop engine, as ignition key will not stop engine if fuel solenoid is tied up. I fuel shutoff solenoid does not lift, engine will not start. If solenoid pull up just a little, engine will start and you will have low fuel flow causing low power.
When I purchased mine the drive home was a nightmare. It would go for about 5-10 miles then loose power to where my unit would only do 20 for a while and die. it would start back up and do the same thing 100 miles later I found some extra filters in the roof compartment changed them and made it home. It has done this a few more times and I have changed the three filters about five times I need to drain the fuel tank but just waiting to get under 50 gallons.
First thing I would do now is cut the filter open and see if it actually plugged up and go from there.
My history with fuel delivery problems for 8.3 Cummins in 1996 Foretravel.
Owned this motorhome for 17 years. Performed all maintenance and most repairs. No trust of professional shops and unwilling to work to their schedule.
Six years ago, a series of intermittent "partial power" incidents occurred. Caused by the fuel shutoff valve (FSV) binding when opening. This condition restricted fuel for high power. Usually had enough power to roll out; not to accelerate (swiftly). Among these occurrences, I pissed off Dallas drivers while on an elevated single-lane overpass going 10mph. When home, this intermittent-reduced-fuel condition was corrected by removing this electrically-operated (normally ON/OFF; not partially open/OFF) valve. Cleaned the valve and its moving parts. Repaired a keeper ring internal to the valve that caused binding. Re-installed; monitored future operation. (FT forum offered a temporary fix for this condition. Secure this valve open with wire or a wire-tie. Remove restraint for shutdown.)
For two years, I chased a small fuel leak. (Only happened when engine operating.) Leak finally enlarged enough to locate source—a crack in the Lift Pump. $40 Lift/Transfer pump 3917998 replaced in May 2016. (Note: I heard a "clunk" when inserting this new pump, holding this part in-place, as a helper inserted the attaching bolts.) No fuel leakage, or oil from crankcase, detected.
Then fuel delivery problems again. Often, starting led to unexplained shutdown at idle. In cruise, intermittent fuel starvation. (Transmission would downshift from 6 to 5 and then 5 to 4, attempting to maintain set speed. Usually corrected itself before progressing to shutdown. But not always.) Did I install an "under-sized" lift pump? Shutdown became the normal result whenever power loss reared its occasionally unsafe or usually embarrassing head.
Changed Primary and Secondary filters, although Secondary was almost new. This did not help. Generator, driven by a small 3-cylinder diesel engine, ran well as it drew fuel from same tank as big engine. (Generator fuel lines had been replaced several years ago.) So, I dismissed "poor fuel" as cause. However, my 21-year old, 24-foot, fuel line from Tank to Primary Filter could be compromised with air leaks or blockage. As well as the 4-foot line from Primary Filter to Lift Pump. Or objects swirling in the fuel tank, randomly sucked over the tank outlet. Or ....
During a Spring trip, removed FSV and temporarily replaced with wire-tie to hold full open for that day's drive. (Wire-tie removed and fuel lever on HiPressure Pump hand-moved to Off position to shutdown for remainder of 3-week trip visiting ancient Indians in NM-CO-AZ.) Replaced fuel return-check valve in Cortez CO (Cortez Diesel). New one broke while I installed it. Re-installed old one. After "bleeding system" of air, the engine would not continue running using manual pump on Lift Pump to prime for start. (Wife and I became proficient at "bleeding the system" after filter changes and return-check-valve swap.) Repeated (six times) the electric "air purge" using Primary Filter setup. Engine remained operating after start. Electric-Priming became procedure for restart when it quit—to get home.
- 10 June 2016: Replaced Fuel Return Check Valve 3924726 (Arkvalleydiesel, $21).
- 16 June: As advertised, ordered a $403 new FSV 4089574 from Arkvalleydiesel. (This was the original Cummins part.) They sent a Synchro Start 3935649 instead! (Previous online purchase $65, China-made, 3935649 did not hold open—after "starter circuit" of solenoid released when ignition key position changed. Only the "ignition circuit" solenoid portion was powered. Ignition switch? Failing relay in hold-circuit? Perhaps wiring was different on this revised model of FSV?) Barry's photo on Foretravel website has this numbered part as a replacement for original FSV. Cummins Technical Service Bulletin contains testing and installation details for this Synchro Start FSV: minimum pull-in voltage 8.3, min hold-in voltage 4.4, energized rod length 2.93 inches. Returned over-priced Arkvalley unit for credit. Much "fiddling" (I appreciate that this might be a professional term.) with my previously purchased 3935649 FSV unit to discover correct adjustment for open and closed conditions.
- 22 June: a (now) bookmarked forum thread includes other additions, considerations, and changes to the fuel delivery system. Some useful, such as: installing a fuel pressure gauge at HP, and the adjustable Tork Return Valve on the HP.
- 29 June: slowly died on way back from a Taos fueling run. Twice! Of course, once while at center of Taos with no way to get off the road. Installed Tork-Tec Adjustable Return Valve. Set for normal pressure. No leaks.
- 02 July: Vowed to re-tighten ALL connections removing possible AIR leaks in fuel system. New washers at banjo connections. Tightened filters; line junctions. Re-cleaned Primary pre-filter and replaced O-rings.
Next step should be a fuel pressure reading. Local diesel shop said, "Have no fittings." And shrugged with a smile. While visiting brother in Kansas, an Olathe truck repair shop technician said he had a gauge and fittings when I phoned. But, did not after I backed in to his slot. Before departing my brother's place, all fuel components had been changed, including the fuel lines. Still had starting problems, and power loss episodes, on way home to NM.
- In December 2017, used CorrosionX on all "drive-by-wire" throttle connections. Sensor at pedal, and all electrical junctions on the engine firewall. This improved throttle response. Test run was okay with wind from behind on level 13-mile jaunt to weigh scales. (... new carpet installed.) On return, into the wind: slow acceleration, with coolant temperature of 170F. (180 was normal before fuel woes.) Reduced coolant temp, even when climbing hills, indicated to me that excess fuel never gets to the cylinders. I still had a fuel-delivery problem.
- Finally, in January 2018, I installed an electronic fuel pressure gage in the dash, $130. (Wires had been laid under new carpet. From snubber+sensor installed on engine, to the former electric clock hole in dash.) Inserted gauge, connected ignition circuits, and 12vdc instead of headlight-switch-ON. This provided continuous dimmed presentation of green lit dial and red needle plus the digital PSI number. Operation now showed that priming, before start, produced 17psi, which reduced to 0 (@30 seconds later) as fuel pressure was spent during start and idle. No one ever said my engine would ran at 0 psi! Nevertheless, this suggested the lift pump was not functional. Removed AC compressor+mounting bracket to expose Tork-Tec adjustable HP return valve. Increased priming pump pressure to 20 psi. (With no lift pump working, I reasoned.) Installed two new air brake valves that switched the cruise control off. These air-electric valves had been reported by Foretravel Forum as being a possible problem for cruise operation.
- 20 January, I ordered a new lift pump, $93. And a stud bolt kit, $22, for relaxed, single-worker installation of lift pump. A week later, I installed the new pump without a clunk. Operation now has continuous idle pressure of 20psi. Parked, no load, mid-range throttle has 23psi. Have I solved my fuel delivery trouble? (A snow packed, descending, twisty road from my house prevents a highway test—for now.) May need to adjust fuel-return-valve pressure for proper Cruise and Climb performance (temp and up-shifting). So, strap AC compressor out of way; leave wrenches for Tork-Tec adjustment on floor near Pax seat.
REVIEW/LEARNED:
1. During installation of second lift pump, piston shaft to engine cam broken-off on previously installed lift pump. (Arm strength created a problem. Mis-directed thinking pushed this to a pointless parts pursuit....)
2. Now, my motorhome has a renewed fuel delivery system from tank to HP. These new components irregularly kept my engine going without an operating lift pump. However, this type of operation did not supply excess fuel to the HP—to help cool the HP as excess fuel went through the HP to be returned to the tank. I hope two years of operation with this lack of excess fuel will not shorten the life of the HP.
3. In-dash fuel pressure gauge allows constant monitoring of fuel delivery. From now on, diminished running fuel pressure should indicate fuel filter changes needed.
4. If priming, or air removal is required, this should be accomplished using the tiny electric pump on the Primary Filter System. Ignition ON and activated with "Purge" button on control panel by poking a slim rod through louvers of engine door. And not the raised bed, heart-attack-inducing-bending-over-extended-left-arm action of repetitively pressing the lift pump plunger.
Thanks for the write up Lewis. I will print this out and take it with me Saturday along with some wire and 50' of rope.
I did change the switches in the front left compartment and it will rev to 3000 rpm now but did not get a chance to road test it yet but I will find out Saturday. :o
Hello Lewis, thank you for useful post. Have you had any issue with cracked fuel lines?
I was told improper adjustment of fuel shutoff valve can not only create non start or running issues, but that it can also cause premature failure if set wrong.
Noticed your tag!
I remember in 1991 while attending a writer conference in Aspen, that I listened to a Russian do the closing speech and using many Um's and Ah's. He had been declared the American Poet Laureate that year. I appreciated that English was most likely his second or seventh language ... but shit, after a hundred of these interruptions, I had begun counting out loud, I got up and left. I wondered at the time, why wasn't Bob nominated as the Poet Laureate for US instead of a Russky? Well, finally, years later, Bob was. "... no success like failure... "
Missed something somewhere,no clue who Bob is!!!!!
Another thing to check in that area is the throttle return springs,should be 2,covered extensively on previous posts.Haven't had
to change my fuel solenoid yet but when I do it would be easy to measure travel and just set the new one for same amount after bench testing.
Thanks John both springs are in place and seem to be providing enough pressure.
Final report:
After replacing the switches in the left front compartment last week I went for a drive today, all is good now ^.^d
Don't forget about the AIR INTAKE! Check out my similar problem, where I serviced the fuel system several times and finally discovered a well packed bird nest in the air intake BEFORE the air filter. It was located in the tube between the air intake grille and the air filter intake. The bird nest was 9 inches thick and had gradually choked off the intake, until it exhibited the same performance problem you have mentioned.
Thanks thisldu, I did take it on about a 10 mile run and the 2 switches seemed to fix the problem but I will go ahead and check the air intake just to make sure.