Recently purchased a Mack CV713 Granite, everything was fine for months recently having a long cranking time before it takes of and runs. initial cranking the engine will burp then act like it needs to prime, eventually it will start after cranking for an extended time. Changed the fuel pressure regulator on side of the block and thought I had it, started 3 times no issue, but before the end of the day it was back to it. Any help appreciated.
Put jumpers or a booster on it and see if it fires right up, if so put new batteries in it. I had one do this to me and batteries and crank speed seemed fine however when cranking ECM voltage must have been dropping to low to activate the injectors. I replaced the batteries and it cured the problem.