Bosch and Denso 'VE' type injector pumps

[mark_in_manchester]

Well, after 10 or more years of messing with my diesel bike, it finally occurred to me (I'm slow on the uptake) that I really ought to understand how the much-feared injector pump works. This was brought on by reading a BR book about 'new' diesel trains (1962) and realising that it might not be that hard, plus a fuel leak around the throttle shaft on my Denso (Bosch clone, I now learn) VE3 type pump which I've been avoiding dealing with as I'm scared of the pump.

Here's a link to a great forum post elsewhere, which describes how these pumps work

https://www.dieselbombers.com/1st-gener ... ation.html

and here's another link to a UK outfit who sell spares, have a great 'interactive parts diagram' to help you order things, and who have been very helpful in response to an email I sent asking for a little guidance. They appear to deal with Kubota and Yanmar pumps too, which might be attractive for people on this forum.

https://injectionpumps.co.uk/

cheers
Mark

[mark_in_manchester]

And here's a video of a cut-away VE pump, in operation.

https://injectionpumps.co.uk/videos/

[mark_in_manchester]

OK, getting somewhere.

These pumps incorporate a manual Cold Start Device, which advances timing on a cam by 5deg to clean thing up a bit on tickover when engine is cold. Above tickover, hydraulic pressure in the pump advances the timing anyway on a curve, as required due to higher revs, and the cam is no longer in contact with the piston which manages the stroke timing. So - why not leave the tickover timing advanced all the time? I've tried this on the way to work today, and could feel no difference in pull at low revs, even with a warm engine. I guess there must be a reason, or the complexity of the manual control could have been avoided...