Mini filters again

[solarman216]

Just got around to doing mine today, it is the Zexell pump, same as on my off road Maverick, except I do not recall the ball and spring, maybe they were removed before I bought it, anyhow clearly the ball and spring are designed to only open at a predefined pressure (note the adjusting washer on the left of the spring) the filter I guess is to stop the orifice becoming blocked but can only be by something from inside the pump as the main filter would not allow such a large particle through, so have removed the filter but retained for now the ball and spring, will test tomorrow but do not expect any change as the filter was clear, this pic is the ball/spring set up

 

[solarman216]

this is the filter and screw used to remove it

 

[solarman216]

and lastly the orifice in the bolt, I did not measure it but guess it is a little under 1mm, so we have two distinct pressures, that of the pressure required to open the ball and then the pressure created by the orifice, having no knowledge of how the governor works on these pumps I can only experiment, Rick

 

[Banshee]

Cracking pics and knowledge there again Rick!!!

 

[rayf3262]

The ECU controls the IP by changing the mark/space ratio of the control solenoid, this in turn controls the hydraulic action on the control sleeve.
In order for this electro/hydraulic action to operate correctly the internal fuel pressure within the IP is regulated to around 70 PSI, this is maintained by the spring and ball bearing.
If the spring becomes weak or dirt prevents a good seal, then the internal case pressure will fall inhibiting full travel of the control sleeve.

 

[solarman216]

The ECU controls the IP by changing the mark/space ratio of the control solenoid, this in turn controls the hydraulic action on the control sleeve.
In order for this electro/hydraulic action to operate correctly the internal fuel pressure within the IP is regulated to around 70 PSI, this is maintained by the spring and ball bearing.
If the spring becomes weak or dirt prevents a good seal, then the internal case pressure will fall inhibiting full travel of the control sleeve.

Exolent Ray, thank you, and if the filter becomes restricted (unlikely I know ) but does this mean the fuel will be increased? Rick

 

[Sweety]

Great stuff Rick:thumb2 this must be on the earlier TD models ?

 

[rayf3262]

Exolent Ray, thank you, and if the filter becomes restricted (unlikely I know ) but does this mean the fuel will be increased? Rick

no increase in fueling is possible by increasing the case pressure. The internal case pressure could conceivably be higher than 70 PSI but this would probably only serve to make the control sleeve move faster.
The ECU has positional feedback from this so will still regulate as per the map.
BUT, if it is too low then it's a different story. Thats one of the reasons why air in the fuel is bad, it causes the IP case pressure to go haywire due in the main to the characteristics of compressing air rather than fuel.

 

[AlexD333]

Amazing knowledge from both of you here :thumb2

 

[kitchenman]

Hi all, the mini filter on my TD is like the one in the workshop,# 10 I think, I guess I have a different pump

 

[solarman216]

Great stuff Rick:thumb2 this must be on the earlier TD models ?

No it is a P reg TDi, Rick

 

[Sweety]

No it is a P reg TDi, Rick

Oh right the Zexell pump set up is so different from the bosch pumps i've had

 

[daniel2609]

have you got a pic of where the mini filter is located? do you need to take anything else off to get to it?

 

[solarman216]

have you got a pic of where the mini filter is located? do you need to take anything else off to get to it?

I did mine by removing the battery, and the rad top up tank, (just push to one side) and the power steering tank, you can then just get to the banjo bolt 17mm,on the rear top of the pump, Zexell, cannot remember the Bosch set up, Rick

 

[AlexD333]

I did mine by removing the battery, and the rad top up tank, (just push to one side) and the power steering tank, you can then just get to the banjo bolt 17mm,on the rear top of the pump, Zexell, cannot remember the Bosch set up, Rick

Seems fairly involved unless you are competent like yourself :thumb2

 

[kitchenman]

The workshop 10 write up makes it clear and easy

 

[panelbeater]

bosh is on top at front and a 17mm long extension is needed to get to it and mini filter is in banjo,i drilled it out on both my t2.

 

[Banshee]

If the spring becomes weak or dirt prevents a good seal, then the internal case pressure will fall inhibiting full travel of the control sleeve.

I presume that this is then what causes the fault code and MIL light

 

[rayf3262]

I presume that this is then what causes the fault code and MIL light

Yes, its likely it would throw an error either related to control sleeve position error or a number 1 injector NLS.

 

[lee 4x4]

I took mine off the other day (Bosch) and got to it without moving anything but is tight getting it back on.