internal injection pump pressure

[bwv]

Here is a photo of the top of the plunger assembly; the indented part designated by the red arrow -- this is manually pushed down to increase pressure, correct? Can it be tapped while still in the pump? How would one measure the distance from the top of the assembly to the top of the indentation? And could one do any serious damage to the pump as a whole by tapping too far down? I am not about to do this without determining first the internal pressure -- I am just curious.



In this image, just to confirm: the blue arrow points to the core of the assembly, i.e., the part that is pushed/tapped down or up to alter the pressure. The red arrow points to the plunger, that is, the part that moves to allow fuel to the pump inlet. Thanks very much.

[libbybapa]

Here is a photo of the top of the plunger assembly; the indented part designated by the red arrow -- this is manually pushed down to increase pressure, correct?

Yes

Can it be tapped while still in the pump?

yes

How would one measure the distance from the top of the assembly to the top of the indentation?

I wouldn't measure the distance, I would measure the internal pressure.

And could one do any serious damage to the pump as a whole by tapping too far down? I am not about to do this without determining first the internal pressure -- I am just curious.

The only potential issue I can forsee is that if one ran the pump with the pressure set way too high, then perhaps it would cause a seal to leak. If run that way for a considerable time I can also imagine that an overly advanced timing could occur in mid rpm range and cause some poorer fuel economy or even a burned piston if accompanied with excessive fuel. All of that would seem to be in an extreme case. I would adjust with the pressure gauge installed. If I went significantly overpressure I would remove the valve and tap it back the other way.

In this image, just to confirm: the blue arrow points to the core of the assembly, i.e., the part that is pushed/tapped down or up to alter the pressure. The red arrow points to the plunger, that is, the part that moves to allow fuel to the pump inlet. Thanks very much.

Nope, what you are pointing to with blue and red is one piece. The plunger and spring are inside that piece and not visible. The part you tap on is also the spring seat and not visible either.

Andrew

[Fatmobile]

I was thinking this was some kind of adjustable orafice, tap it down, it makes a hole smaller and increase the internal pressure but that's not what it sounds like.
It does kinda look like the center begins to block the upper (blue arrow) holes.
So would the twiggy fuel cause this regulator to deliver a lower pressure if it's controlled by a spring and not an orafice.

[libbybapa]

The lower pressure with a lower viscosity is a matter of more flowing out of the "out" bolt orifice. I believe that a better compensation for lower viscosity fuel would be an adjustment of the "out" banjo orifice size, but unfortunately that's not easily adjustable.

Andrew

[bwv]

Perhaps restrict the line(s) leading from the out banjo orifice with a very small hose clamp or something similar? Or maybe splice into the line a very small and simple inline fuel filter to slow things down a tad. There must be some sort of brass fitting or other related device on the market that would allow one to adjust the flow of a liquid through a line. (A quick google search brought up this: http://www.allstar.fiu.edu/AERO/Hydr16.htm and this: http://personal.inet.fi/yritys/innovanet/misc_parts.htm) We are talking about a fairly small degrees of restriction, correct?

[libbybapa]

Yes it's a small hole. Pull an "out" bolt and look at the orifice. Very small. A variable restrictor can be had at most local hardware stores for cheap (small needle valve). I've been curious about doing that, but have been concerned about diesel rating and whether or not one would get proper adjustability.

Andrew

[Fatmobile]

Perhaps restrict the line(s) leading from the out banjo orifice with a very small hose clamp or something similar?

If you grab the line going back to the tank and restrict it... prepare to be showered with diesel as one of the little lines between the injectors pop off.
You'd have to route them to the low pressure side of the restrictor.

[redprimer]

Just got and am reading the Bosch Diesel-Engine Mangagement Book (3rd Edition). Quoting from page 196 --"In applications where higher internal pump pressures are required for low-speed operation, an overflow valve can be installed in place of the overflow restriction. This spring-loaded ball valve functions as a pressure-control valve" There is a schematic of such a Bosch valve on page 245.

In the above quote "low speed operation" might be analogous to our case of interest here -- high speed operation with low viscosity fuel? Seems plausible but don't know.

It would be interesting to get a part number for such a thing and see if Bosch has an application sheet or any kind of data on flow characteristics.

[libbybapa]

I'm pretty sure I have one of those valves from a Landrover TDI pump. A modified "out" banjo.

Andrew

[redprimer]

Great, see if you can get a part number off it and maybe we can track down some cracking pressure/flow data or (and definitely more fun) maybe we can test it?

[hagar]

If you are reading this -- you are drinking from the " Holy Diesel Grail " ----so we must make sure that the stuff in the goblet --is -CORRECT ? EH ?---This is where Fraulein Bunny Bondo got her endless smileage from.

Picture # 1. --Red arrow point to the "slug" that we drive (push) up and down .----CORRECT.

at hagars the BOSCH VE 107 IP is the "GRAIL" (VW number) and Diesel-engine management --2 nd edition is the ---" BIBLE " .---by BOSCH.

The pictures show a Pressure-control valve ---NOT to be confused with a Pressure-regulator.

The 107A comes with a valve stamped 37. four holes just above red o ring . one hole where blue arrow points. on picture # 2.

hagar.

PS : I shall keep an eye on you guys ---IMHO you are headed for the land of "SMILEAGE".

[Fatmobile]

Just got and am reading the Bosch Diesel-Engine Mangagement Book (3rd Edition). Quoting from page 196 --"In applications where higher internal pump pressures are required for low-speed operation, an overflow valve can be installed in place of the overflow restriction. This spring-loaded ball valve functions as a pressure-control valve"

I've been thinking about this, while tooling down the road in bunny Fatso, and it doesn't seem like this could be a spring loaded pressure regulator. If spring pressure was used to control the pressure the spring would open at a certain pressure and it would stay the same.

The plunger and spring are inside that piece and not visible. The part you tap on is also the spring seat and not visible either.

So if there is a spring maybe it contols the minimum pressure.
It still seems to me like the center taps down and covers holes>

an overflow valve can be installed in place of the overflow restriction

This also sounds to me like there is normally a restriction in the bolt that.
I can see how thinner fuel would effect this regulator if it's hole that allows more fuel through as internal pressure increases..
Thinner fuel would also be more likely to slip past the vanes and reduce the amount of fuel being pumped.
Less fuel being pumped, more fuel flowing through the pressure regulating restrictor hole and "OUT" bolt. I can see how this would lower internal pressure.
I was trying to think of a way to make one of the stock "OUT" bolt extenders that Libbybapa used for his pressure gauge. Before I bought some tapps and dies I made a trip to the dealership to see if they could get them and how much.
Found out that they can get them, they ended up being on backorder but I finally got one and it's not near as long as the stock extender bolts.
The part number changed and the piece is much shorter.
The hex area is about 13/16" or 20mm.
I can probably figure out a way to mount a port on it but if it took 2 of the others to get it up high enough for a TD pump, it might take 3 or 4 of these..... I got it for around $9

[FineFrank]

My setup:
(insert picture here)

I used a pedestal from a n/a diesel and drilled and tapped a standard compression fitting in order to use a mechanical oil pressure gauge.

Andrew,
What part am I looking at? I'm no noob, but I cant figure it out.

Frank

[bwv]

Another view of the pressure control valve:




I also found this on the web. Might of some use to somebody. Caption is:

Pump number 0 460 494 135 (84 Jetta 1.6lTD) VE4/9F2250R134-2

[redprimer]

Just some opinions on the normal inlet/outlet options. Just opinions -- don't really know anything.
The normal flow restriction on the outlet is essentially just a hole. The normal pressure control valve has a spring loaded piston in a bore. As pressure lifts the piston against the spring, the movement of the piston uncovers a port in the wall of the bore. As pressure continues to rise more of the port is uncovered. This port is essentially a "leakage" path from the outlet side of the vane pump to the inlet side. So when the port is uncovered the back leakage reduces the effective rate of fuel delivery to the pump body by the vane pump and so reduces the rate of pressure increase in the pump body as a function of rpm. Essentially if the vane pump delivers fuel to the pump body at a certain rate the pressure in the pump body must increases until it is sufficient to drive fuel out of the output restriction at the same rate.

When you tap down on the plug that acts as the seat for the spring in the pressure control valve you increase the preload on the spring. This means that it takes more pressure to move the piston and if nothing else changes this shifts the control span of the valve to higher pressure.

So say we're at a steady 2500 rpm and assume the pressure control valve is a least partially open (I have no idea what any of these numbers actually are). Well there will be a certain pressure in the pump body and certain timing advance. If you held the rpm constant and reached in and tapped the seat deeper into the pump until the pressure control valve was fully closed (and stayed closed) the backleakage around the vane pump would stop, so the rate of fuel delivered to the pump body would increase, the pressure in the pump body would increase until the flow out through the flow restriction balanced the fuel delivery of the vane pump and because of the higher pressure the timing would advance.

Of course knowing even some of the numbers would be nice.