Fourby boost pin and ring

I’ve been fairly happy with my 300 tdi 110 sw, its gone well but black smoked a bit at high revs and pulling away, I’m now using her for work so I came across fitting a boost pin, which I did first and turned the pump mixture screw out to try and stop the black smoke, after doing this pulling away was a joke, I had lost all power until the revs picked up and then boom we’re off, I thought that you must need the boost ring as well as the fourby video puts both on, I fitted this today and an egt gauge, pulling away is slightly better but not as good as it was before I fitted them.
The fourby video for the boost ring has two springs and two little washers (originally) my pump only had one spring and one big washer, I fitted the 3 that came as well.
I don’t know wether the pumps been adjusted on the dial where the pin is.
Can anyone enlighten me how to get the initial pulling away power back or is this something I’ve now got to live with, on the hills I’ve tried the egt gauge can be pushed up to around 670 degrees with a light haze of black smoke ?.

It is my understanding that the boost pins only work if the rest of the pump is standard and has not been tuned at all. If the pump
Has been tweaked the boost pin will not give the desired result. It would be better to use the original pin and turn the pump accordingly or return the pump to standard and then fit the boost pin.

Thanks for replying,
How can you check wether the dial disc thingy that you see when you take the pin out has been moved ?.

Unless whoever altered it etched/punched alignement marks at the start then I do not think you can. The only way to get it back to original in that case would be to give it to a Bosch fuel pump specialist to reset.

Farmie said:

Thanks for replying,
How can you check wether the dial disc thingy that you see when you take the pin out has been moved ?.

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Dead easy to check, if you look at the std pin you should only see one heavy mark, if theres more than one mark the pump has been messed with, even then just look for the heaviest score mark and turn the pin so the mark/score is aimed at the front of the vehicle, job done!
Of course if they have adjusted the max fuel screw thats not so simple, but again think logical and measure the visible thread on your pump and ask on here then average out the results and take that as a std measurement.

@battenberg any pointers?

Cheers

Ok I’ll have a deco, thanks.

My original fuel pin only has one mark.

Farmie said:

My original fuel pin only has one mark.

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Well you cant argue with that!

Is the plastic or metal seal still on the max fuel screw? it got a 6mm spanner size head and screws into the back of the pump.

No that’s been adjusted before me, I’ve now turned it out 1/2 turn to stop it smoking so much.

Turning only the max fuel screw is the bodge way to tune the car, at least when the fuel pin is turned clockwise you only get more fuel as the boost climbs.

thread resurrection alert...

Is the Fourby boost pin still the best modded pin to purchase? Seeing a lot of knockoffs being sold online.
Asking for a friend with a D90 and a 300 engine.

JUKE179r said:

thread resurrection alert...

Is the Fourby boost pin still the best modded pin to purchase? Seeing a lot of knockoffs being sold online.
Asking for a friend with a D90 and a 300 engine.

Click to expand...

All the boost pins have the same problem, they give the engine to much fuel in off boost situations which means they smoke badly, very badly!

I thought you can turn some nut anticlockwise to lessen the amount of fuel consumption?

JUKE179r said:

I thought you can turn some nut anticlockwise to lessen the amount of fuel consumption?

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You can certainly try, but guarantee it will still make smoke off boost with heavy throttle
Std boost pin 1/8 to 1/4 turn clockwise. same for max full fuel screw, and the modified boost ring makes them pretty driveable with very little smoke.