Forum Discussion

TEO's avatar
TEO
Explorer
Aug 26, 2014

CAT loses power

About 6 years ago my CAT 3126 started to lose power intermittently. I changed the fuel filter, but that didn't help. I took it to a CAT dealer and it was diagnosed as dirty oil. I guess the oil pressure operates the injection system or something. At any rate, it worked. The problem resurfaced a few days ago and I again replaced the fuel filter, but it didn't solve the problem. The the RV would slow down and now I got a "check engine" light. Last night I stopped at a Walmart and replaced the oil and filter. This morning the RV ran perfectly, taking hills with no problem. After about 8 hours, the problem returned. Now I'm stumped. I'm with in 15 miles of 3 CAT service depots and will go to one in the morning, but I'm wondering what to expect.

Paul
Class A
  • Passin_Thru's avatar
    Passin_Thru
    Explorer
    Aug 28, 2014
    It sounds like it could be the fuel filter isn't full also. Mine loses power when it's not full and if not bled by loosening the screw on top and pumping like mad it will never run right.
  • TEO's avatar
    TEO
    Explorer
    Aug 27, 2014
    I took the motorhome to Carter Machinery in Salem, SC. The tech attached a computer reader and had the codes in a few seconds. I needed a sensor and a solenoid. Parts and labor $600.00 out the door. There was no wait, no hassle and no problems. The engine runs like new.

    Paul
  • RayChez's avatar
    RayChez
    Explorer
    Aug 26, 2014
    I had a similar problem like that. I changed the fuel filter and the air filter. I got more power now then I ever had. It goes up grades with ease. I think it was the air filter more then the fuel filter that was causing the problem.
  • badboy368's avatar
    badboy368
    Explorer
    Aug 26, 2014
    maybe you could let us know what you find out. its the same engine i have and am curious....:h
  • wolfe10's avatar
    wolfe10
    Explorer
    Aug 26, 2014
    Yes, the Caterpillar HEUI injection uses oil to operate the high pressure injectors.

    First thing I would do is check fuel system PSI at the secondary fuel filter (verifying that there are no leaks on the suction side of the pump and that the lift pump is functioning as it should).

    Also verify that the exhaust brake is not hanging partially closed.

    Sure there are other causes of low power, so if neither of these, have a Caterpillar dealer check for stored codes.
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Aug 26, 2014
    I started getting check engine (goes into limp mode; 1/2 power) with my C-7 a few months ago. Dealer wanted $175 each time to read codes so I bought a Silverleaf system for my laptop; $310. Works great.

    You also get pretty good tech support diagnosing codes from Silver leaf.

    It told me I was getting either high pressure or no signal from the turbo boost sensor. I have it scheduled for a full service next week and the tech said he could test that one and/or replace it if its the cheap one.

    Cross my fingers.
  • Jones1's avatar
    Jones1
    Explorer
    Aug 26, 2014
    Had problem with my 3126 (99') few months ago and it was the water/fuel seperator. I had changed the oil and fuel earlier but didnot changethe seperator. Theengine would turn rpms but would not make any power. Water/seperator solved the problem. You might check this.

About Motorhome Group

38,709 PostsLatest Activity: Mar 12, 2025