Just a quick one, was doing an engine midlife on a 962k and one of the components to be changed was the high pressure fuel pump. I figured it was just a bolt off - bolt on affair but after checking SIS it said it needed timing pins. Long story short, I eventually got the inj pump pin in place and changed it out. My question is, surely there is no need to time a high pressure pump when it is going to a common rail set up? Bitch of a thing to work on, no room to get at anything
It needs to be timed. The pump does deliver in a series of pulses due to its design, and if you don't time it, the pulses don't coincide with injection and it will affect performance. These pulses are wide enough to accommodate injection timing variations.
Cheers for the reply. Interesting to know. I've fitted an array of high pressure pumps to lots of different makes and never had to time one before. Luckily we had a timing pin squirrelled away to suit the pump here
If it's any consolation, I thought exactly like you the first time I set out to fit one, until a Cat field follow guy put me right.
It would be interesting to find out if the System Operation explanation for the fuel system in SIS clearly explains the way the pump works and the need to time it..?
It makes sense, but I would not have thought of it at first look....
I took a quick look in Systems Operation but did not see the explanation for it.
This same situation is common on Komatsu engines that have the fuel pressure pump going into the common rail, the drive gear is marked for TDC No1 fitment. tctractors
It was covered briefly in a course I did several years ago. From memory the common rail pump is a piston pump (2/3 pistons depending on if the engine is 4/6 cylinders, but I may be wrong on that detail) and yes, as ih100 says, the pumping pulses have to be timed to the injection sequence.
hi ,here is some info on the common rail set up on the 7.1 engine as fitted to the 962K. it uses a rotary style high pressure pump with a single cam ring which supplies 3 plunger strokes per revolution. the C6.4 and C6.6 and the C9.3 engines use an inline high pressure pump with a camshaft and two pumping elements Perkins Cat and Mitsubishi Cat high pressure pump Mark
Thanks for that, nice to know the reasoning behind the instructions
The C.6.6 had Cat's own fuel system, the C.7.1 has a Denso system. I haven't tried it, but apparently they will run with the pump slightly out of phase, and power loss is noticeable.
I know that once timing is slightly out, on the pumps with the speed sensor on the back ( C6.6) the injection is disabled and can be a tricky one to troubleshoot a no start situation.