I have had this roll off truck for just a little over a year. When I had it inspected, the man told me I had a plus because it had the fuel pump replaced because it was a slightly different color and had yellow markings at the injector lines and a few other places. I about fell out when he said it usually runs about 3 grand to do a Mack pump because I have always been a Cummins dude. Ever since I got it, it hardly had any real amount of smoke come out like most other Macks I see that do and it has a delayed turbo boost. I had a slight miss when idled up a few rpms so I bought a set of exchange injectors from Mack put in by another shop. At first it seemed like it did a little better then went back to the same thing the next day. I returned it back to the shop and he suggested I take it to a Diesel injection shop as he said there was a pump problem and not injectors or the work he did. At times I can pull up to a traffic light and when I take off, the truck wants to go like crazy and a large cloud of black smoke behind in which I barely have smoke come out at all and after that, it is real sluggish as usual.
If I mash the pedal to the floor and hold it, it will end up dying unless I let off the pedal a schmid and wait for the boost to kick in. Or I can just ease down on the pedal going down the road just to gain a little speed and it will kick in and again if I floor it, it will continue to die. Now it seems like I am losing power real bad when I get to a hill while I have an empty or half loaded Vac Box which are normal after dumping the majority of the load off.
The truck has about 350,000 on it, it is a 1997 RD688 with an E7 350 mechanical and a Fuller 8LL. Top end is about 75 to 77 and about 82 downhill .... I can hit 80 and top a hill at 55 and before I could top it at 65 on the same hill any other time so now I know I am having more of an issue ... Any answers to this ???
NOTE: rubber strap in picture was used as a test to make sure I was getting full throttle