Fueling issue on MK1 Golf GTI Cabriolet/Convertible

Hi. I am new to the forum so hi to everyone. I spent all night last night reading through posts regarding my problems and has helped me greatly so far.

I have a 1984 GTI Cab.

It has been sat for around 2years. Previously it has never failed to start with a battery to move around etc.

Put some fresh fuel in it etc. Engine is turning over but not firing.
After reading a post I tried easy start to rule out spark issues and it does fire.

Next step I loosened fuel pipe to the filter inlet. Fuel is pumping well when cranking. I cannot get the outlet bolt off and didnt want to break it. I have also checked the 5th Injector and there is fuel under pressure getting to it. I have also loosened injector lines on top of the Metering head but no fuel coming out under crank.

After reading another post I removed metering head and the flap/plunger moved up and down when pushed with some resistance and air/suction noise which I assumed was ok.

I am stuck what to do next. I was thinking about getting a new fuel filter or does someone else have more diagnostic checks to carry out.

Many Thanks

Update: Held Metering flap up, Turned her over and started!

Now, I am not great on petrols as I have always had tdi's.

Would this be a vacuum leak?

Any pointers for a GTI novice would be great…

Thanks

The injectors could be blocked up slightly causing them to only open up under full flap opening, pull them out and check that they spray when the pump is running and the metering head is lifted up slightly, I would imagine they have just varnished up after sitting for a couple of years, you can clean them in a solvent and ultrasonic bath, failing that the metering flap is a bit sticky due to being sat in the same position for so long.
A major vacuum leak would cause this problem also but is quite unlikely, whack some fuel system cleaner in the tank and run the pump for a bit and start it with the flap lifted to get some fuel flowing through the injectors, that should sort it ;-)

Thanks I will try that.

When manually moving the flap should it be fairly easy to move but feel like you are squeezing air out with like a sound as if you were pumping up an airbed!!!

Does anyone know how far it is open upon normal operation so I can run it for a few minutes. Would prefer to take injectors out as a last resort until I can get it in under cover.

Thanks

you would hear an air leak kinda like a high pitched squeel,

take the injectors out before messing with the fuel dizzy,there is a guide if you unsure m8 :dontknow:

I had a bit more of a play with the metering flap earlier. It will start and tick over if pushed about 1cm in. Would this mean injectors ok? I could hear an air leak sound. Seemed like it was on top of metering head but couldn't be sure. Is there anything on there that is anything worth worying about or could be to blame.

If not I will take your advise and wait for a dry day and test injectors.

Thanks

check the corrugated rubber hoses as they can perish and split, especially by the throttle body where the extra pipe goes into it, also make sure that all the breather hoses are attached,

argh!!! 1984, do you have an electric throttle switch on the manifold and what looks like a vacuum switch mounted on the metering head? if so then your overrun fuel cut off solenoid could be sticking open and bypassing the metering unit, I don't know where it would be mounted on your car but it would have two half inch or so hoses going to it and an electric connection, one hose would go to the metering head under the flow plate and the other hose would go into the manifold somewhere by the throttle I believe.

out of interest, how are you lifting the metering flap up?

Thanks very much I will take a look in the morning and try and get some pictures. I got someone to turn the engine over and pushed the flap up with my fingers with airbox unclipped/open.

Cheers!

The fact that it starts when you push the metering flap up probably means that there is some crud, fuel gum or the dreaded rust blocking the four metering head slits that feed fuel to the injectors.
Has the fuel filler neck ever been changed or rusted out ?
The metering head plunger can be removed for cleaning and checking, if there is any sign of rust then in my opinion it will be beyond repair and you will need another metering head.
They are a sealed system but if water has got through the filler neck then when the rusty particles get to the metering head they will just rust it out. Sitting for two years will not help.

I think mine is same as above picture.

Is there a guide for checking the metering unit.

I have owned the car 8 years. I haven't had the filler neck changed since I have had it but not sure beyond that.

Does a vacuum from the engine turning over normally open the flap that I am having to push open?

Thanks in advance. The only reason I want to get it going as I am being pushed to get rid or restore and didn't want a non runner plus the existing bodywork to sort. At least if I could get it running I would only have the paintwork to sort!

92k on clock it too young to die! lol!

Vacuum from engine will normally lift the flap up enough to spray fuel in to start it, if you say you are lifting it about 10mm then that sounds reasonable and it is working  enough to start the car, was it even trying to fire up without lifting the flap?

The flap should be fairly light to lift and you should feel a change in pressure once the fuel pump runs

My guess is still the solenoid if it is fitted, if not then yes you may have varnished metering head but there is a fuel filter before it that really should be stopping c**k getting through :-)
have a good look for the overrun solenoid and just clamp the pipe shut so it isn't able to bypass the metering unit, that has to be the easy option, I think it is attached to an extra relay on top of the fuse box if that helps

On the wifes cabby, she has the vacuum switch and throttle closed switch, but it is definately not and overun cut off valve.
The vacuum and throttle switches work in conjunction with the TTS and CSV to provide a burst on fuel enrichment when the throttle is pressed quickly and the TTS is not up to temperature.

Was this different on 1984 cars ?
Hers is a 1993.

Just an update. Took the Air Auxillary valve off and noticed it is 90% closed even when turning over cold. Voltage is at the switch at turnover but no movement. The 5th Injector is not spraying.

Bypassing the AAV results in 5th injector spraying upon turnover and the flap in the metering head moving up and down itself resulting in the engine firing. Unfortunately I am out of fuel so not sure if its the solution although I put 10L in and seems to have gone very fast. Off to get some more fuel tomorrow.

Does anyone know how the AAV should be in operation? Open/closed etc? Thanks

AAV should be open and closes after a time when it has got a 12v feed (ignition)

Not sure about what years had acceleration enrichment, thought it was a later thing and that the overrun bypass had been fitted earlier as a fuel saver, normally the K-jet metering unit is capable of giving acceleration enrichment but I think it couldn't quite cope when cold:-)

sounds like you may be getting to the bottom of it but I am sure you would have been giving some throttle whilst trying to start it which is pretty much what the aav does anyway! maybe all that fuel has cleared the system a little!

did you ever fix this issue?  mine is doing exactly the same thing.  plunger free and light, gets heavier when pump is on, but only runs if i lift up the arm about 10mm, then fires first time, doesnt seem to be able to lift it itself?