Adjusting 4JG1 Fuel Pump

[iananita]

This question seems to get asked a lot so here is a write up to adjust the VE Bosch fuel pump on a Holden Jackaroo (UBS69) with 4JG1 motor. I do not have a boost gauge or EGT gauge so have not over- fuelled. This is what the boys do when they dyno tune the pump. I had my Rodeo 4JB1 done and it made a big difference, there was plenty of smoke on boost after they did the Rodeo.
Now the Jackaroo was going ok, I have had a 2.5" straight thru exhaust for 12 mths now and been meaning to get around to do this. I have tuned it to smoke only on heavy acceleration(boost)and may need to tweak it more yet.
The fuel screw is at the rear of the pump under a green metal cap. The cap needs to be removed and usually is damaged in the process, you do not need it.

Top view fuel screw.JPG

The red square marks the fuel screw it has a 1/2" (13mm) lock nut that need to be loosened so the fuel screw can be turned clockwise to add fuel (anti clockwise to reduce). You will do this using a blade screw-driver. This only needs small turns at at time ie 90*. Mine needed 360* to get black smoke when heavy acceleration on road test. When you turn this screw the engine's idle speed will increase so you need to slow the idle speed down by adjusting the idle screw at the front of the pump(see picture) I have fitted cruise control to my truck so the Green circle bracket will not be on OME pumps.
The yellow squared studs 10mm will need to be removed to gain access to the boost compensator adjustments.

Top view Idle screw.JPG

The idle screw + lock nut are 10mm and can be adjusted to reduce your engine's idle speed after adjusting the fuel screw. By turning my fuel screw up the revs increase about 1000rpm. The Green arrow is the end of the cruise control cable not on OME pumps.

So take off the boost compensator cover, remove the 4 studs and you will find a black diaphragm. Make sure you mark the position of the diaphragm with a white pen, we are going to rotate this 90* clockwise. Carefully remove the diaphragm. Take care there is a spring(not under tension) and nylon washer under this to reveal the Star wheel which we will also adjust.

Boost Diaphragm refitted resize.JPG

Here is a close up of the top of the diaphragm, it has an alignment mark on the bottom of the diaphragm which I marked white so I could see it once refitted. The mark was originally turned to the bottom of the pump.

Boost Diaphragm Diagram.JPG

This is a side view of the control pin under the diaphragm, notice the different ram angles, by turning the diaphragm we will get more fuel added as the boost increases, I turned mine 90* clockwise to gain the ram marked with the red arrow.

Boost Control Pin.JPG

Before this diaphragm is replaced, you can adjust the the Star wheel which controls the tension on the spring. Turning clockwise reduces the tension so the control pin moves with less boost ie the engine will boost earlier. Mark the wheel, I turned mine 2 full turns.

Star wheel.JPG

Now replace the diaphragm with spring and washer, Turn it 90*.

Boost Diaphragm rotated.JPG

Notice my mark is now facing forward. Replace the cover. Once these internal adjustments are made it is time to adjust the fuel screw, adjust the idle speed then road test. Repeat as many times as needed. Remember if you are going for big boost and fuel up lots there will be an increase in EGTs which will cause problems ie turbo failure, overheating

Good Luck

PS there are plenty of you tube clips on this just search VE Bosch
This article is a great reference http://autospeed.com/cms/A_109345/article.html

[Captcol]

On my pump I do not have the adjustment screw as mine is some form of efi, would this still work?

[mudslinger]

nice write up. does this work for 2.8 pumps as well?

[iananita]

nice write up. does this work for 2.8 pumps as well?

Yes, VE pumps are all similar.

[iananita]

On my pump I do not have the adjustment screw as mine is some form of efi, would this still work?

No, EFI pumps need to be chipped

[jellis]

this is great.
ive had that article saved for months and havent had the balls to attempt it.
but now some one else has il be doing this very soon

[andrewward0377]

thank you this is very helpful, I have a question, at the turbo how can I adjust the boost I was told to turn the stem rod that is fixed to the valve 2 time clock wise is this correct, and how do i do it ?, thanks again

[iananita]

thank you this is very helpful, I have a question, at the turbo how can I adjust the boost I was told to turn the stem rod that is fixed to the valve 2 time clock wise is this correct, and how do i do it ?, thanks again

At the turbo you can fit a boost valve in the rubber hose which controls the waste gate. You will need a boost gauge to do anything here. If you do have a gauge, try putting a ball bearing in the pipe first see what boost it will get, but be careful, you will need to do this on a road test, put the engine under load, back off if it's getting over 16psi.

I have found that boost valves do not work on their own unless you are fueling up your pump to suit. The most boost you can get safely is 16psi, there is also a manifold valve that will open at this pressure. When I had my Rodeo(4JB1) dyno-tuned it was running 12psi, with no boost valve.

[andrewward0377]

thanks for this thread, but I have a question, my engine is a 4jb1 and the cap is different to this shown here and it is not as simple as this one to remove there are some other bolts/screws which I am worried about some kind of bracket that holds the idle speed adjuster in place, if you had the same engine i would appreciate some help here, thanks again

[andrewward0377]

does this work on a 2.8 4jb1 TD

[jellis]

http://www.landroverweb.com/Pdf-files/T ... _Rev_2.pdf

thought this was worth posting