Diesel Pump

[deian]

Hi all,

Recently, there's been a lot of talk about tweaking the mechanical Bosch pump.

Could I be cheeky enough to ask someone to take a picture and locate everything thats adjustable on it, and what the effect is of a particular adjustment. I know it's all there in the text of recent threads.

I read these threads with interest and I become lost but keen.

I wanna fiddle too I know jack about these pumps and they seem to be the heart and soul of the diesel engine.

Thanks.

[MikeT]

If you search for my thread "No black smoke" there's a link that started me off learning how these pumps work.

[Peter.N.]

The fuel adjustment screw is on the back end of the pump just above the injector pipe unions, it usually has a seal on it. It screws in to increase the fuel but it is very sensitive, only move it a fraction of a turn at a time.

[davek-uk]

Do a search for "bosch ve pump adjust" on the internet. There’s quite a lot of info here – American and VW. One of the best ones is http://www.dodgeram.org/tech/dsl/more_p ... wer_ve.htm but this doesn't have any good photos. It does give a couple of drawings that are useful. You really do have to get inside the boost part of the pump to understand what to do.

Basically there are four pump adjustments:

• 1. Off boost fuel (the smoke adjustment) screw. On top of the boost "flying saucer" you'll find a brass-ish cap. This pulls off to reveal a hex screw and a 13mm locknut. All it does is press down on the Boost delivery spindle as the screw in screwed in. Good for improving off boost pull. Without any other adjustment screwing this in will give better running. After doing the other adjustments, however, you’ll probably need to screw this out to reduce smoke.
  
  2. Boost full load fuel delivery rate. Inside the "flying saucer" - undo the 4 hex bolts. A pin within the pump pushing against this tapered spindle. The top of the spindle is a diaphragm and the boost air pressure pushed the spindle down giving the adjustment. The diaphragm and spindle will pull out – you may have to turn it slightly to free it (beware that under the diaphragm, on the shaft, is a nylon spacer and a tension spring). The bottom of the spindle is an off-centre cone and the whole diaphragm and spindle shaft can be rotated. The pin pushes in from the front of the pump (left as you look at it –camshaft end) – with the diaphragm and spindle removed look down the hole in the pump. The more travel the pin has the more fuel will be released. Reassemble accordingly.
  
  3. Boost rate. The spring under the Boost full load delivery rate diaphragm determines how easily the boost pressure pushes down the spindle. The spring tension is adjusted by a star-wheel under the diaphragm. Push the diaphragm down to get a feel of how tensioned it is to start with. The star-wheel clicks around and can be adjusted by a flat-bladed screw driver (or by hand with the diaphragm and spindle removed). Turn the star-wheel clockwise to lessen the spring pressure.
  
  4. Max fuel screw (Power adjustment screw). This is external on the rear (outlet end) of the pump. On the later guarded pumps it is apparently under the guard. Although looking at the pictures I’ve seen on the internet it looks to be above the guard. I haven’t done this yet (could you tell?) Screw this in for a greater max fuel flow. As Peter says it is sensitive, so do part turns at a time.

All I can say is I have adjusted 1 to 3 and the pickup is far, far better than it was. Remember to take note of how things were so that you can take a step back if the adjustments don’t go to plan!

Dave

[jgra1]

thanks Dave, very useful

John

[deian]

I second that. Thats spot on Dave, just what I was looking for.

The best part is.. now I know what the pump is called: VE!