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Jeremy
Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 2781
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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I AM WORKING ON A 2006 MACK CV-713 WITH A 427 ASET,

Customer Question

HELLO, I AM WORKING ON A 2006 MACK CV-713 WITH A 427 ASET, IT HAS AN ENGINE MISS ON CYL. #5. SENT ALL THE INJECTORS OUT AND 4 ARE BAD SO I INSTALLED 6 REMACK INJECTORS AND 6 NEW LINES, MISS ON CYL. #5 IS STILL THERE. I DID NOTICE WHEN I CRACK #5 CYL THAT FUEL DOES NOT PULSE LIKE THE OTHER CYLS. DO, IT JUST RUNS HEAVILY OUT FROM THE UNIT PUMP/LINE AREA. IS THE UNIT PUMP STUCK OPEN AND I'M SEEING RAIL PRESSURE? THANKS GREG
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 1 year ago.
My name is ***** ***** I will assist you with your concerns.
Sounds like the pump is stuck open or the harness is bad. These ASET engines are really bad an having bad harnesses because of how they lie so close to that exhaust manifold. The shield can only hold back so much heat. I wouldn't be surprised if you remove the shield, use an air gun to blow all the junk that built up there, and lift the harness it will be sticking to the galley that the harness rests in. If so, expect the possibility of a bad harness.
Now on the pump not pulsing, that very much sounds like a bad pump. I would swap the pump and see if the issue moves. If so, replace the pump. If not, replace the injector harness.
They are not the easiest to do. I usually remove the shock off the back of the cab and jack the cab up and put a block under it, then crawl under the cab on a piece of plywood to get to the 2 bolts that hold the harness in place. I'm a big guy at 6'2" 290 lbs and can just squeeze in there. I found that to be the easiest way to do that harness when they are bad.