Help!! I can't sort this problem with my Karman!

Hi Guys, new member here with what I hope is not a major problem!

Hope you can help, managed to secure the car of my dreams Golf MK1 Karman Convertible and disaster struck the other day.

While it was idling I heard a PSSHHHHH noise, quite loud and abrupt!  I thought that it came from the near side in the engine bay around the fuel filter and the car then died!  

Symptoms

Engine idles but only after raising idle speed as it had dropped to about 500rpm from an average of around 1200rpm. No misfire at idle and idles happily at around 800rpm when warm.
Very difficult to start but was prior to current calamity.
Engine temperature normal.
Engine won't rev up and backfires through the inlet manifold when revved.

Parts recently changed:

Spark plugs
HT leads
Fuel Filter
Air Filter
Rotor Arm


Parts checked:

Air leaks - all hoses checked for damage and no leaks found
Fuel pump working but using a fairly high current of 7.6A (normal range is supposed to be 5.5A - 8A)
Air/fuel control flap in metering head checked and found to be central and free to move as normal
Fuel injectors not yet checked
Compression tested recently but prior to problems - consistent compression readings in all cylinders.

Does anyone have any ideas to help!?  Really frustrating as you can imagine but the joys of owning a cult classic!  Happy motoring all!

Regards Jon Mac

first post and a paid member topman welcome to the forum

ignition timing ??

Matt-

I'd be pulling the injectors out and checking to make sure they aint peeing fuel out at a stupid rate, by raising the idle speed you are allowing more air in, so sounds like there might be a bit too much fuel in there - perhaps a faulty metering head?

If you need a hand give us a shout - only in chesterfield

I had a cabby that did something like that , turned out to be the rev /gearchange vacumn pipe had disconnected from back of the clocks.       If you need a tool for pulling injecters ross let me know , also have a new set of seals

Many thanks for the suggestion guys,

I will be trouble shooting accordingly, Legend rossirvine on the offer of an extra pair of hands…

I will be uploading some pics of the MK1, have booked in the MK1 meet looking forward to it already!

Will keep you update,

Thanks again peeps….

Karman Update Here…

Have now tested all fuel injectors and spray pattern was consistent and as they should have been.  No leakage from the injectors until the metering head plate was moved up! So it's not an expensive metering head! Winner!!

Have also checked the 5th injector to make sure it is not stuck open, which it is not.  (although it's not working so I think I have discovered why it has been nightmare to start)…

However this has still not solved this current problem of not revving.

Any further suggestions guys, could the ignition coil be on the way out or possibly could the cam belt have jumped a tooth?

Thanks again guys