[cumapart]

It’s a commenrail system that builds pressure all the time, timing is 100 control ed by injectors, if the gear has been off the fuel pump they have a procedure on Cummins quick serve to time the pump, if buying a new or recon pump they must likely come with the gear already installed and don’t require to be timed as far as I know, however don’t trust what I say read the instructions on quickserve, Just a warning to any1 replacing fuel pump head or replacing barrels and plungers and roller tappers, MAKE SURE to a-line keyway dowel in the cylinders where roller tappers go in, they should be pointing strait up an down and NOT SIDEWAYS or any other direction for that matter, roller tappets have a notch machined on one side, that is made to a-line with the keyways in the cylinders in the fuel pump block, you can feel dowels when fuel pump head and tappets are removed, you will have to reach down in the cylinders, you can turn the dowels, failure to a-line when reassembling will result in dowel breaking off and fuel pump and possibly engine damage, it is a good idea to inspect camshaft as well when checking fuel pump plungers, pins, and tappets, don’t mix up barrels and plunger pins when taking apart, they are a matched set, Cummins recommends to update to newer 2 piston pump if your engine still has the older 3 piston, some 2 piston pumps came with CERAMIC plunger pins and tappets with brash roller pins, if your fuel pump head is still good these parts can be swapped out for the steel plunger pins and updated tappets, and you will have to be very clean when working with the tight tolerances of this system, if you have a gear of the front gear train, make sure to pin crank and use appropriate timing wedge for your engine, GEAR BACKLASH MUST BE SET CORRECTLY by a mechanic who knows what he’s doing, just my 2 cents

Peterbilt did the work, replaced the pump with a new pump. Changed fuel lines. I had the old style pump and they had to upgrade to the new pump style which required changing the fuel lines. It vibrates hard at idle almost feels like it’s doing a regen but it’s not. Engine has tapping noise at low idle and follows the engine into rev up until over 15. Is is your truck stock with mandate intact, or are you running a tune with to much timing or perhaps other bad practices, just asking