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Tpflyer · 07-08-2013, 11:02 AM

A few months ago we got a check engine light while driving home in our 2010 Tour42AD. We stopped and called our Freightliner dealer who normally services our chassis. I got the diagnostic code off the computer and it translated to low fuel pressure in the #1 fuel rail. I drained the fuel filter to see if there was any crap in it and it was clean. I decided to limp back to the dealer. We made it back. The light would come on when the throttle was depressed and would go out when feathering the throttle. Th FL dealer changed fuel filters, upgraded the computer software after speaking to a cummins rep. Test drove it and it was still doing the same thing. They did some other test and then test drove it and it was fine. Kept it another day and test drove it and it was again fine. Now fast forward a month to this weekend. Driving out to the race track for the weekend and bang on comes the check engine light. Call them on Friday to set up to bring it in on Sunday. On the way home it was fine for the first 30 miles or so than bang, on comes the check engine light but this time it stayed on no matter what I did with the throttle. Limp home, unload the coach (about 2 hours) then drive to the FL dealer no light at all. Its like it knows it is going to the doctor. Kind of like my cat. Hopefully they will find the problem this time as we are headed out again on Friday.

greystroke · 07-08-2013, 11:15 AM

Sounds like an intermittent sensor or a loose wire somewhere. That is assuming there is no fuel leakage. Sometimes rodents get into wiring. I would inspect the line from the sensor to the computer.

Tpflyer · 07-08-2013, 11:45 AM

Certainly a possibility. I think they need to ascertain whether the fuel pressure is actually low when the system says it is. If it is low then there is a blockage somewhere, maybe a piece of gasket material floating around in the system, or a problem with the pump, or a fuel supply problem. If it is not low when the system says it is then it is either computer, wiring or sensor. Since I am not a Diesel engine mechanic all I can do is speculate. As long as they fix it permanently I will be happy no matter what the cause. Ill post the findings when they get it fixed.

HeapBigEngin · 07-08-2013, 12:37 PM

Trying to understand your concern. When the light comes on, do you see any noticeable performance difference, i.e., loss of power, stumbling, hesitation, etc.? I can't really decipher that from your original post. If no real performance difference, then, as Greystroke mentioned, it sounds like a sensor is reading an "out of range" condition somewhere. Loose connections or poor grounds can do that, of course, especially within a fuel injection system....have learned that lesson a couple too many times!

Please let us know what you find out....it will be helpful to many methinks. Thanks!

Tpflyer · 07-08-2013, 01:13 PM

I guess I should have been more clear in my original post. My understanding is that when the check engine light comes on the computer switches to a lower power setting automatically. My guess is that my horsepower went from 400 to 200. Thats just a guess. I could maintain speed on a level surface but any incline whatsoever and the speed would immediately drop off in some cases I had all I could do to maintain 30 MPH. That was on about a 4% uphill grade.
When I said I limped home, trust me I was limping. We had to disconnect the toad and have the wife drive behind me so we would at least have a chance at making some of the New England hills on the way home.

Tpflyer · 07-10-2013, 12:26 PM

Just got the motorhome back from Freightliner of Hartford. They took it on a long test drive to duplicate the conditions. They got the Check engine light to come on and verified my experience. After some diagnostics they replaced the fuel rail pressure switch. Another long test drive confirmed the repair. We are headed to Atlantic city on Friday so we will see if it is really fixed.