BAC Forum
General Boards => Technical Support => Topic started by: Mike Nunn on July 28, 2015, 04:48:13 PM
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We were coming home from a short trip when the check engine light came on and we lost power. The silver leaf said it was fuel pressure delivery fault. We are at a freight liner repair shop now. They thought it was the fuel filters so changed them but that was not the problem. Now they think it might be the low pressure fuel sensor but they can't locate it. Does anyone know where the sensor is located or have any other ideas? 2007 Beaver Contessa 400hp Cat engine. Your help is really appreciated. Mike Nunn.
Ok they found the sensor and that isn't the problem they are checking the check valves
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Mike can help you but you say 400 hp. Cat engine. Is it a C-9 400hp or is it a C-12 400 hp.
This makes a real difference in helping you with your problem. Sounds like they are starting
to throw parts at a unfound problem. Did they connect up Cat ET yet and get any more info?
Dave Atherton Retired Cat Mechanic.
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It is a c9 they have all the software and have the computer hooked up. It shows no problem except low fuel pressure
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Mike back again, C-9 list of Causes low fuel pressure
1. Fuel Tank Vent / Cap
2. Fuel filter Primary and Secondary
3. Fuel priming pump GP.
4. Fuel supply / Return lines
5. Fuel Pressure Regulator on rear of engine
Dave Atherton Retired Cat Mechanic.
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Thanks Dave, they have changed both filters fuel in filters was perfectly clean and it made no difference. They unhooked the sensor and put gauge on fuel line and the pressure is actually low.they are putting on a new check value in the return line now so we will see, there did seem to be some issues with it. It was worn enough that you could see the port was not round at all and there was an o ring completely missing, so we are hoping.
If this is not the problem I will mention your other suggestions. I really appreciate your help. Mike
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The repair shop just called and said the coach is ready, the check value seemed to fix it. I will take it for a test run tomorrow before I get too excited though. Dave thanks again for your help .
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Mike, how many miles on the coach? I'm curious how the check valve got so worn that it actually slipped an O ring.
Joel
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Joel, maybe I can answer your question on the fuel regulator on rear of engine head. This little
check valve has a very small hole to pass fuel from back of engine head to maintain back pressure
of fuel in the cylinder head at base of this housing there is a check valve with o-ring Very small in
size. What happen this o-ring gets hard and and will not seat plunger or o-ring breaks apart.
If engine is run in a low fuel condition ( air in fuel ) the fuel regulator will hammer with air /fuel
and o-ring will fail. In most cases again low fuel pressure will cause failure. How long will regulator
run before failure is anyone guess. Note. Removing fuel regulator can be serviced with replacement
of o-ring and make sure small hole is not plugged. If you have been reading some of my earlier
Post I have mentioned fuel pressure regulator problems as to the one above.
Dave Atherton.Retired Cat Mechanic
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Joel, the coach has 40,000 miles on it. Not sure if Dave is actually talking about running low on fuel in tank but it has never been below one third and seldom below one half if that was the condition he was talking about. I watched the tech. Take off the value and there was no o ring or pieces of one.
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Mike,what I was talking about not fuel in tank but low fuel pressure, from fuel filter. Your
fuel filter secondary is 2 micron new it has restriction 5 psi. When fuel filter needs to be
changed same fuel filter has a restriction of 10 psi. low fuel pressure to injectors will cause
fuel regulator valve to hammer or chatter. Note: when fuel filter reaches 10 psi engine will
derate. Note: Mike save the faulty fuel pressure regulator and keep it with your motorhome.
All that is needed to repair regulator is 2 small o-rings and make sure the orfice hole is
not plugged and you can see light through office. This may happen again and is easy to
repair yourself on the road. Dave Atherton Retired Cat Mechanic
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Dave, I think I get the gist of it now - low pressure from dirty filters. Mike said the valve was worn, so I'd presume he'd not want to reuse it. Then again I'm not familiar with these engines like you and others, so forgive my ignorance of exactly how the regulator and valve are configured. But you mentioned him keeping the entire regulator, whereas Mike seemed to be talking about only the check valve being replaced.
Joel
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Joel, this fuel pressure regulator ( check valve ) is just a check valve about 3 inches long
hex housing that is threaded on both ends and splits in the center ( thread with o-ring ) to
access to the Check valve. Inside housing check valve has a Allen head socket that holds check
and spring in place. What a person is going to find at check valve is o-ring missing on seat
of plunger and maybe still in housing pieces or has passed on return line back to fuel tank.
This is a very small bore inside of housing assembly and o-ring is about guessing about 3/8
round. On earlier s/n engine the plunger was plastic with o-ring, later engine s/n plunger is
metal. The plunger end is located downstream where the return hose connects. Note: I carry
with me at Beaver seminars this fuel regulator and explain the above can be serviced along
with other parts that can be serviced on the cat HEUI system that will shut engine down along
road. These repairs I mention are not hard to repair and get you going till new part can be
located. Just need some brake cleaner and few tool that most everyone has on board motorhome.
I have passed on troubleshooting fuel system low power and have explained how you can
Locate these fuel regulator if it is bad. This little thing can get very costly if you are on the
road again, but owner can be in control of problem and save lots of money.
Dave Atherton Retired Cat Mechanic
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We picked up the coach today and drove about 50 miles all is good.
Thanks Dave and Joel for the help. it was a 40 dollar part too bad it took a full day to chase it down.mike
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Mike, one thing about your problem it was a minor repair as far as parts go. It seems lately
there has been several motorhome owner that spent big bucks at repair shops and left with
same problem they stopped for in the first place. The end result repair was corrected with
help of the beaver membership and owner doing the repair that was very minor in cost. In
most cases things happen going down the road are very minor in nature but there is not money
enough for repair shops to repair and replace a minor part. The cat electronic engines are built
for the long haul at minor money outlay. Dave Atherton Retired Cat Mechanic
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Mike
We are at the FMCA rally with the Beaver Security FORCE and Dave Atherton has been holding some interesting conversations with many of us that have the Cat engines. He is a wealth of knowledge and we are lucky to have him in our Beaver Club and on our forum.
I believe that with the knowledge Dave is sharing I may be able to reduce my annual contribution to the CAT "stealerships" !!
I have that dressed "ck engine " light on again but I show no active codes on the computer yet Cat wants to install a new turbo. That would be 3 turbos in 3 yrs. No thanks I think Ill just drive with the light on for awhile till we can get to the root of this problem. With no help from Caterpillar I might add!
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All: FWIW - I have an intermittent check engine light. Have had it for a couple of years. Have had it checked out several times to no avail. (ie no codes -no lose of power,etc. I have been told by several mechanics that have tried to trace the source of the light it could be something as simple as aweak light ballast. Good luck. p.s. a small piece of electrical tape helps the light go away :)
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Dan, we did have a fault code that indicated low fuel pressure so at least they knew which direction to start.
Niel, I can get the check engine light to appear by trying to increase the speed of the coach with the cruise control if I press it multiple times. If I want to change the cruise setting now I just turn it off and back on and hit set and I do not get the light. The silver leaf never showed a a fault when this happened. Maybe someone can figure that one out I gave up on it.
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Mike, most Cat event codes require the use of factory passwords to clear the code.
some parameters are protected from unauthorized changes by passwords. Factory
passwords are provided only to Cat Dealers. ( this is where Cat has control and cannot
go around the system. ). If several mechanics apparent not Cat mechanics at Dealership
cannont locate any logged events codes than problem is wiring, bare wire ground interminent.
connector. There are a group of 5 Volt sensors that are all connected to ECM with wiring
And is like a Christmas tree light one light go off the complete string is off. With the sensor
group a mechanic has to address each 5 volt sensor and in this case light may go off.
It is possible a 5 Volt sensor is shorted to ground. I like the above a piece of black tape
would work great. Dave Atherton Retired Cat Mechanic