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pump diaphragm stuck


nino

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following from my post that i have no power

plenty of boost so theres no problem there

i took the injectors out and cleaned them up as was a bit sooty but wasnt able to try another set

took the top bit off the fuel pump where the diaphragm is and that was stuck down with no movement, prised it up and it now moves up and down but i cant take it out fulley to see where the cone shape bit is facving because it now runs like theres no turbo on it??

also when spinning it round there is a tight spot maybe that has something to do with my lack of power a siezed up part of the pump??

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your boost fuel pin is seized, I've been meaning to write an article on this for ages as I'm seeing it more and more.

This may be a pain to fix and may need to take the top of the pump off to strip down and clean. But before going that far I have fixed it once or twice by doing the following.

Get a fresh can of WD40 and spray a ton in the breather hole and around the piston under the diaphragm.

post-3730-0-04534300-1297123213_thumb.jpg

Then move the throttle to full, let go and then pull the piston up as far as it will go and rotate it 360deg. At full throttle the pin is forced out a little way and then pulling up the plunger and spining forces it back.

Do this for a long time and you may be able to un-sieze the pin enough to remove the plunger and then use a small screwdriver to work the pin back and forth. It should move freely with no resistance.

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I had exactly the same problem on mine and eventually took the pump to a specialist to get it stripped down and when fitted back to the vehicle, what a difference! Your vehicle will be running short of fuel and thats why it will feel so flat when throttle is pressed.

A "how to guide" for this problem would be very welcome Im sure. ;)

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ok cool i try that or wot pary of surrey u from for me to bring it to u lolwill this problem cause it to drive like theres no turbo?

yes that is the exact symptom, basically as you tried to pull the piston out, that then forces the fuel pin to it's lowest point, it should ping back, but as it's seized it just stays at minimum fuelling. basically the turbo is doing nothing.

I hate playing with fuel pumps, everything need to kept so clean. Don't know any good people your way to rebuild the pump, but down in Hove, I'd recommend Automarine diesel. Was impressed with their service.

I had exactly the same problem on mine and eventually took the pump to a specialist to get it stripped down and when fitted back to the vehicle, what a difference! Your vehicle will be running short of fuel and thats why it will feel so flat when throttle is pressed.A "how to guide" for this problem would be very welcome Im sure. ;)

I'll try and find the time to knock up a guide

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i think its broken

i squirted loosing oil in and around the plunger turning pullin and pushing and then eventualy the plunger came out with brown yukky stuff all over the end. cleaned it off and put the plubger back and kept woorkin it up and down and spinning about till it was free with no tight spots

put all back together started it up and it now runs rough, smokes a bit at idle and dont rev up

what have i done??

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no, you missed a step, your were not trying to free off the piston, you were trying to free the fuel pin. Getting the piston out was the first step.

here's how it works:

post-3730-0-50043700-1297204781_thumb.jpg

so now you have the piston out your trying to free up the pin (green bit) applying full throttle should move the pin out a little, you can then stick a screwdriver down the piston hole and push it back. Keep working it back and forth until it frees up.

Cheers

Ruu

meant to add the reason it's now running really badly is as you've pulled the piston out the pin has moved back further. I.e the further the pin is to the left (in the diagram) the less fuel, more fuel to the right. So when everything is working right, the turbo spins up and pushes the piston down, the pin then runs along the tapper of the piston. More boost, more fuel.

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well the piston was tight anyway so thats now free

if i full throttle and the pin donr come out then what do i do is there a way of getting it to move out or is it pump strip down

take it that this pin is not now letting me rev the engine up

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oh dear, afraid it's not good news if it's not moving out at all. Apart from filling up the piston bore with WD40 or penetrating oil and leaving overnight it's probably going to be a top of the pump off job.

There's a few good fuel pump articles in the tech archieve about how to remove the top of the pump and reassemble. That's what I followed when I first did this job.

But this is what the pump looks like with the top of in situ:

post-3730-0-93419300-1297206329_thumb.jpg

and this is the underside of the top of the pump:

post-3730-0-40896600-1297206347_thumb.jpg

The black leaver in the centre pushes against the pin and this can be used to push out the pin a little way. But to be honest I have a pump sitting on my shelf in bits like this and I still haven't managed to unseize it yet. So no guarantees. I believe a 300tdi pump should fit straight on.

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ill think i pop down and fill it with loosing oil and see wot happens

looks like i wont be goin to play at the weekend as it be spend workin on the bloody thing

eill be goin back to it thursday so i let u know wot goes on, thanks mate

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  • 3 years later...

Did you ever manage to get the pin freed up???

I'm just experiencing the same problem now.

I can't get the cone out at all :(

I'm gonna try pushing the throttle full on and rotating the cone through 360'

Maybe a few thousand times.

The wd40 was applied last night and the tools will be out when I've finished work.

Fingers crossed :)

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