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I've been rebuilding pumps for 10 years and this "internal pressure" discussion is IRRELAVENT.  This mod is a performance mod...  not some method to skip a pump rebuild because of a worn feed pump or to fix substandard fuels.  It is intended to squeeze more power out of an IDI diesel with a mechanical injection pump, not to restore or change internal pressures.  Increasing the pressures to achieve this type of advance would blow the seals out of the pump.  Besides, you couldn't increase the internal pressures anywhere near enough to gain the advance that this mod gives you.  If you want better acceleration, mod the advance mechanism.

Funny how the story changed from what is clearly a performance mod to "restoring internal pressures" and compensating for ULSD.  That was not the theme of my original post, but the replies somehow shifted.... hmmmm   Again, the discussion is irrelavent.  


It's real simple...  you can do it, or you can not do it... nuff said!

Wow a fight...
take it easy mate. For a mechanic with such experience why so sensitive ? sure your spring fiddling will increase advance with no increase in int pressure but your performance mod also mentions an improvement in economy. What Andrew suggests will also give an improvement in an ageing pump. Restoring internal pump pressure just up to factory levels can't be a bad thing and shouldn't blow healthy oil seals.  
I put it to you that improvements to economy and performance can also be achieved by those who don't feel confident enough to enter the pump simply by rotating the spaceship diaphragm.
 If anyone is looking for improvements in economy as a priority then reducing break pressures in injectors will work (as long as nozzles are running correctly) This goes against conventional thinking but so did Darwin... This might explain why Lucas pumps can achieve 85+mpg imp on a run whilst injectors only operate at 120 to 130bar.

We can all learn more even when we are as experienced as you obviously are. Shame you haven't posted more  than your 5 sessions or we'd all be up to scratch on your hidden talents.
Having said that you won't be touching one of my pumps as you appear to be well rehearsed in throwing serviceable pumps away. Is your work commission based?... Oops a little low that blow...
 Anyhow keep posting so that the non mechanics here can be helped )

As I said before... the regulator is at a FIXED pressure.  Of course if you destroy the regulator, then yes you can change just about anything.  I still stand on what I said before...  the VE pump is designed to run at a certain internal pressure at any given speed.  At the beginning of that "how to" it specifically says "Pressure in pump MUST be 43.5 Psi at 1000 RPM engine"  which is correct. That's 500 pump RPMs as stated in the calibration manual.  The one thing you really don't want to mess with is the internal pressures.  it causes premature failure of the seals.

You take a small punch and tap the center of the regulator in slightly to increase internal pressure. Do so in very small increments while measuring the internal pressure.

Wow, such an accurate way to change a critical setting!  Yes, it works for a while...  until the pump blows a seal.  How can you expect something you've damaged to work reliably?  Ever think that when you tap in that regulator, you're changing the shape of the piston as well?  so now it's going to get stuck sooner or later, what happens then?  new seals.  why take all that risk?

The spring mod uses VW parts...  VW parts that have been installed in other VW's... undamaged.  Removing the thicker shim only provides for less spring preload so advance happens a little earlier.  The lighter spring was used in the Vanagon as a stock part...  so how will the timing be over advanced?  I've done literally hundreds of pumps and most are using the green spring with thin shims....  and are still running.  Like I said, you can do the mod, or not do the mod...  or go ahead and change something Bosch says is a critical setting... it's your time and money to replace the pump.  As for this forum...  I'm finished here.  feel free to destroy your pumps at will...  I was giving you a safe alternative.

Alas he obviously had hands on experience...
But his words of the apocalypse commeth for all alternative ideas to his own was a no-no  :roll: Smells commission based...

To hijack this thread that is now vacant :shock: ...

Why can't I use vaccuum from the exhauster to run a Cruise Control system? :?:

Here the original  ''BOSCH'' tool to adjust  pressure regulator:

   

And here the description of the BOSCH ESITRONIC software:



The majority of the IDI pump, the pressure are 0 - 100psi, and for a specific DI pump, the pressure can go up until 160psi, and no seal leak.

To adjust the timing curve, it's more easy with the regulator, and it is conceived has this end.

And for the regulator them even, there exist with different pressure curved, (different hardness from spring, different size of bleed port and 2 or 4 bleed port)

TDTech, it is not your knowledge which is in question, it is rather your attitude opposite this.

If I were done has your first lines, you will learn some here than than you learned on this subject lasting 10years.

A forum it is not a place to claim itself to have infused science, one is here to discuss and exchange our experiment.