Injector pump throttle arm shaft adjustment

joebillhill · Post by **joebillhill** » Thu Jun 29, 2017 9:14 am

Hello all,
A while back I had a top seal leak on my injection pump and decided to take a crack at fixing it.
I followed the instructions laid out here on the wiki (https://www.socialtext.net/m/page/delic ... eak_repair) and the pocuk page they took it from (http://www.pocuk.com/forums/viewtopic.p ... eb34bc350f)

It all worked out in the end but in my haste i didn't mark the throttle arm shaft to reinstall it in the right spot.

"Look carefully at the throttle arm shaft and you will see a groove machined across it (if it is obscured by yellow paint scrape it off) get the ruler and draw a line on the throttle arm with the felt tip pen to line up with the machined groove, this is so you can reinstall it on the same spline. (There may well be a witness mark already scribed on the throttle arm anyway). If lined-up wrong it will either not idle or idle way too fast, but no big deal to work-out later. "

My question is: is there a way to get that throttle shaft to factory spec? Or else do i have to adjust it through trial and error? I haven't seen a witness mark on there but maybe I'm not looking hard enough..
The van lays down a lot of exhaust "smoke" at night with it slightly under load so I'm trying to eliminate that
Thanks in advance,
Joe

Post by **Growlerbearnz** » Thu Jun 29, 2017 2:24 pm

You can figure it out by the idle speed, it should idle at 750rpm when the idle speed screw is about midway in its adjustment range. If the screw needs to be at one extreme of its range to get the idle speed right, the arm needs to move one spline.

Smoke under light load might be a few things, but if it goes away at higher boost levels it's probably the boost compensator spring adjustment under the diaphragm. Wind it up (counter clockwise) one turn and see if it helps. That puts more spring pressure on the diaphragm, preventing it from increasing the fuelling until the boost is higher.

joebillhill · Post by **joebillhill** » Mon Jul 03, 2017 10:39 am

Ok good to know. I think my compensator is fine. I get up to 9 psi pretty quick (pedal half depressed or so) and it still blows smoke.
I've discovered that my tachometer is off at lower rpms so I'll have to track down a sensor and then adjust it to the correct idle rpm.

joebillhill · Post by **joebillhill** » Tue Oct 10, 2017 11:09 am

When adjusting the boost compensator is removing the nut above the diaphragm required or is it just rotating that nut and diaphragm in tandem?

Post by **Growlerbearnz** » Tue Oct 10, 2017 1:17 pm

joebillhill wrote:When adjusting the boost compensator is removing the nut above the diaphragm required or is it just rotating that nut and diaphragm in tandem?

No need to remove that nut when rotating the diaphragm, the whole diaphragm/nut/metal plate/control shaft/cone rotate as one unit:

: VEdiaph.JPG (71.02 KiB) Viewed 3720 times

Rotating the diaphragm moves the offset cone towards or away from the control mechanism, changing how much fuel is injected by the same amount at all boost levels. If your engine smokes almost all the time (acceleration, steady cruise, light traffic) rotate the diaphragm to move the cone towards the front of the IP.

Winding the serrated wheel under the spring changes the spring tension, causing more (or less) fuel to be added when the turbo's boosting. It doesn't change the fuelling at idle or under light boost. If you only have smoke when driving hard, wind this up.