Squealing noise

I have an s1 gti. When I turn the ignition on and the fuel pump is running there's a funny squealing noise coming from around the metering head. Any ideas? Thanks. Andrew 

I'm not sure if this helps or not but I have a series 2 1.8GTI and when I turn on the ignition and the fuel pump purges I get a brief high pitched sound. I've never really investigated it and my car has done it ever since I got it running about 18 months ago. I thought it could be the injectors taking up the pressure that was being built up behind them.

Thanks for the reply mate.
I've discovered what the problem is. 
The plunger is stuck in on the metering head and filled all the cylinders with fuel.
Does anybody know how to free the plunger? 
Thanks 

if its stuck chances are the metering head is toast unfortunately, if the car has been running up till now chances are its debris thats made its way past the filter. if its been sat it could just be old fuel clogging it up and if so it may be salvageable, but still have to try and get the pin freed off which is tricky without damage

Thanks for the reply.
Managed to get the plunger free but still won't work properly. 
Going to try a different fuel distributor on the metering head. Can understand why there is so many different ones, do you know if they are interchangeable or what the differences are?
Thanks
Andrew 

I'm not sure how many different fuel distributors there actually were. I thought there were only two, one for the 1.6 and one for the 1.8.
I had a 1.6 FD fitted to my 1.8 but it wouldn't run right and I was told they weren't interchangeable as the 1.6 engine had a different power curve so the metering head was set up differently. I was also told that the WUR was different as it matched the different FD's. It will start and run though, it just might not run properly.

the 1.6 also used the 1.8 metering head at one point, with a different WUR to match it.

main thing is check the part number on your metering head and WUR, then we can advise moving forward

Thanks for the replies. 
The problem is the car has had a full nut and bolt rebuild and it won't start. All the valve timings correct, ignition timings correct, good spark, fuel pressure tested up to metering head all good. Now tried a different fuel distributing head on, appears to be working but still no go. 
So running out of ideas? 

If you're sure that you have the valve and ignition timing correct, good spark and HT leads in the correct order along with fuel at the FD then you need to check you have fuel at the injectors. Do you have fuel in the cylinders/wet spark plugs? If not you need to remove the fuel pump relay and either link out the 2 big pins or replace it with a relay that switches when the ignition is on to power the fuel pump permanantly. I'm not familiar with an S1 so I don't know the relay layout but the Haynes manual might help. You also need to remove the injectors and the ducting from the metering head. I used old baby bottles and put an injector in each one, switched on the ignition (the fuel pump should now run continuosly) and using a magnet I lifted the plate in the metering head to allow fuel through. You should get a conical spray from each one. If you don't you need to remove the injector from the hose and see if fuel is getting there. Just make sure you have a means of catching the fuel. If you still don't it sounds like you have a problem in your FD again.
I hope this helps, let us know how you get on.

Thanks for the info.
I think the problem could be the fuel injectors, took them out last night and the seals are rock hard and the injectors don't look promising, will try them over the weekend and get new seals. 
This is how it's looking so far. 
Hoping to get it finished just after Christmas 

The car looks amazing, do you have any more pictures? Did you do the resto yourself?
Good luck with getting it finished for Christmas, keep us posted on progress as I look forward to seeing that car running!
The injectors don't look great. Did you see if they were spraying fuel and did you have fuel in the injector pipes when you removed them? One thing I did forget to mention, when I was setting mine up after it had been standing for over 7 years I removed the injectors and had the fuel pump running continuously. I then adjusted the mixer screw until the injectors just started to squirt fuel and then I backed it off until they just about stopped. When I tried to start the care it fired up almost immediatly. I bought my injectors off eBay from a seller called tierod69 but Classic-VW do brass ones for £25 each, a good price!

they look to be coarse thread M12, so you will be ok with the merc stuff. but yeah, check them first! they dont look too bad at first glance,. quick clean up they should come up ok. but tbh its the inside condition we care about not the outside

Thanks for the replies. 
Cleaned the injectors, put new seals on, and eventually she fired up. 
Sounds good but won't tick over at the moment, but now it's running I should be able to get it to the Vw centre to get tuned.
The problem is getting it up and down the drive as the drive is very steep and awkward to do when it's not running.
Yes I did the restro myself apart from the painting, but still a bit to do on if yet, still no seats in the front and few other jobs to do. 
Needs to go back to the body shop for flat and polish as well. 
So I took the other mk1 out for a 200 miles blast at the weekend to celebrate.
Here's a pic so you can see how steep the drive is