Thread: 300TDi flatspot at 3100rpm

Originally Posted by Tank

I would say that because the fuel rod that is controlled by the diaphragm would only be allowing a set amount of fuel through, when it reached 3100rpm there was not enough fuel to rev higher, as a working diaphragm is pushed down by boost from the turbo the fuel rod moves backward, increasing fuel supply, if it doesn't move the rod will be in it's furthest ahead position and supplying that amount of fuel which was not enough to rev past 3100rpm, hope this helps, Regards Frank.

Hi Frank,

Yeah, I'm very familiar with the workings of the Bosch pump which is why I was curious...

You originally said that the flat spot disappeared if you lifted the throttle & then reapplied. With the tear in the diaphragm, when you re-applied the throttle, I would expect to see it flat spot at exactly the same place again.

Anyway, I think it's one to tuck away in the back of the mind in case I see it again. (I suspect that as these vehicles get older, we're going to see more & more fueling issues like this.)

M

Ahhh... OK.

BTW - When you re-assemble, you might want to give everything a smear of grease as it has now been exposed to the 'moist' air. Over here, it's common for the pin to seize completely as we add a nice mix of salt during winter too!!

M