Help needed - fuel injection on MKII Golf GTIs

Stonedofmoo

Stonedofmoo

Stonedofmoo

Soldato
Joined
24 Oct 2002
Posts
6,242
Location
Portsmouth
Afternoon all

We recently bought a C reg MKII Golf GTI 8v. It worked perfectly for the first weekend, but 2 weeks later when we came to move it again it had compleatly died

Engine turns, but doesnt catch. Anyhow RAC man came along and reckons fueling. So do we as we've now changed the dizzy cap, rotor arm, spark plugs and coil pack and charged the battery etc but it doesnt even sound like it's trying to catch

Now, we have tested the fuel pump is working by simply disconnecting the incoming fuel line into the fuel injection unit on the left hand side of the bay, as soon as you start the car it primes and fuel sprays everywhere with a decent amount of force.

Now here's the bit we dont understand.
If we disconnect one of the fuel lines going into the injectors on the engine the fuel barely comes out. It doesnt spray out like we expected, it literally trickles out so slowly it would take 10 minutes or longer to fill a cup. This is while we are trying to start the car by turning over the engine, a fraction of the force the fuel pump is sending it to that unit.

I was expecting it to jet out in a sequence depending on the firing order of the car, but it doesnt. I'm convinced the fuel injection unit is at fault then, but if anyone knows more about these cars can they offer any insight?

Thanks in advance
 
dirty injectors would be understandable on a 86 car.

if you tip a small amount of fuel into the throttle will it then fire? have you actually seen the plugs sparking?

if it fires and runs i would recommend some millers injector cleaner.
 
No I disconnected the fuel lines at the fuel injection system end, not the injectors and next to nothing was coming out. And no it doesnt fire even slightly

The electrics in terms of sparks are perfect. The RAC guy tested them and you could see clearly it was sparking perfectly. The engine also has good compression so it's not that either, and was working perfectly up until it's 2 week holiday

Any more ideas peeps?
 
If its mechanical fuel injection as I think it is on the early vag cars(my 1983 Audi was) then you have a fuel distrubution unit at the side of the engine bay, with pipes to each injector that do not have any electrical wiring to them. Then its bosch k-jettronic fuel injection. This fires on every cycle of the engine and not every forth as an electrical system would(so they all fire together). The fuel builds up in the manifold(four squirts) then the valve opens and lets the fuel for that cyclinder in. Sounds like the distribution pump is at fault. Bear in mind that this isnt a high pressure system same as electronic injection though as it has four times as much time to get the fuel in.
 
Dandle said:
If its mechanical fuel injection as I think it is on the early vag cars(my 1983 Audi was) then you have a fuel distrubution unit at the side of the engine bay, with pipes to each injector that do not have any electrical wiring to them. Then its bosch k-jettronic fuel injection.
Click to expand...

Didnt the 8v GTI use a Digifant system, and the 16v use the K-jettronic?

edit: maybe im wrong going by the post below :o
 
Stonedofmoo said:
Yes thats the one!

OK so distribution pump sounds the culprit. Just need to find out where that is now :D
Click to expand...

As far as im aware they can be a right pig once they go wrong, and usually quite costly. IIRC its on the left hand side of the engine bay (looking towards the engine).
 
Before you go any further just been thinking about it. The pump may not be at fault as it works by a diafram thats moved by air pressure, the more it moves the more fuel is let through. The system also has a cold start valve on the manifold which is in effect another injector to give it enough fuel to start initially, this could be the problem. Got people around so cant really post at the moment but check that valve out(its like an electronic injector on the manifold). Will the car start if you turn it over with you foot on the throttle a bit?
 
No it literally never sounds like it's catching at all

I've taken some pics

This is the unit on the left:-
1.jpg


Pipe one is the fuel line, If you undo this fuel sprays out at considerable pressure
Pipe 2 is an example of a fuel line we undid to see how much fuel goes to the injectors. The answer is... a trickle

2.jpg
 
Looking at your first pic at the top right. There is a blue injector on the manifold, that is the cold start injector.
 
I think the first thing I would do is take the black plastic cover off that is just behind the distribution pump, this is where the diafram is that controls fuel flow and make sure it is moving freely. My old car would still start when the cold start injector was broken but required your foot to be on the throttle a little, it wouldnt tick over at all though until the engine had warmed up.(its a while since ive seen this system so bare with me if some of my info isnt exact).
 
Dandle, you're spreading a bit of dis-information there. K-jet only has the one pump, usually in or near the tank (however, sometimes you do get a feeder pump, a low pressure one in the tank). And K-jet runs at about 80psi which is HIGHER pressure than most electronic injection systems. It's also continuous injection - it doesn't squirt 4 times instead of the once of electronic. The injector is constantly firing.

Right, Stonedofmoo. Leaving the injectors attached to the hoses, remove the injectors from the engine and place them nozzle down into a large fuel resistant jug. Needless to say, no smoking, no flames etc. Then you see the big rubber "bellows" near your fuel distributor - that's the big metal lump that the injector hoses go to. Remove that, and under there is a round aluminium disc. There will be a hex head screw in the middle of the disc.

Get your pump running permanantly, on my car I do this by removing the fuel pump relay and bridging the contacts. See your haynes manual as that will probably explain how to do it. My car is a different make so I have no idea how to do it on yours.

Using a pair of pliers, lift the aluminium disc by the screw head. Do the injectors spray? Can you feel any resistance as you pull up?
 
I can only talk in experience of my Audi 100(and im a bit rusty on it) which had the same injection system but on five cylinders. The cold start injector definately makes a difference and as i said mine wouldn't run on tick over with it not working until the engine was warm. I was calling the fuel distributer a pump for want of a better name but your quite right it isnt a pump. The fuel pump on mine(the one in the tank) only started running once the starter had been engaged(but will not run until the starter circuit has been made) but will stop once the fuel is up to pressure in the line. So if its up to pressure and you try again it will not run as pressure is there. The injectors would fire on pressure rather than an electrical impulse(i dont know the pressure of hand but you may be right and its high).
 
Last edited:
ok, silly question but how do you get the flipping injectors out :confused:

We tried pulling on them with some real force, unscrewing them with a spanner and nothing we did could get even one out.

On the other side I took off the rubber bellows thing and could see the disc you described. I could lift that up freely and it lifts without any noticeable resistance.

Finally if anyone knows MKII Golf's where abouts is the fuel pump relay located?

I dont suppose there is anyone in the south area who would be willing to come look at the thing for us. All I want to do is get it running so I can sell it off.
 
Last edited:
Your fuel pump relay isnt faulty if you had fuel pumping out when you disconnected the fuel line and fuel pressure was there(constantly).
 
You must log in or register to reply here.
Back
Top Bottom