16v Metering Head problem or blocked injectors??? - Problem Solved :-)

Hi,

I'm having some starting issues with my car which is a standard Mk2 Golf Gti 16v KR.

Its been sat for a while but had always started, although a bit lumpy so decided to get new leads and plugs. This made the world of difference and I had it idling to get it up to temp, but then it suddenly cut out and I had trouble starting it again.

On checking the plugs they were all sooted up so I assumed it was running rich, so I went through the setting up CO process as in the FAQ but still no joy. It will fire briefly then die straight away.

I'm getting a spark on all cylinders and the fuel pumps both work (or at least I hear them buzz). ISV Buzzes and all 3 temp sensors on the head apear to be working fine.

On pulling the injectors to test I am getting no flow from them at all. Fuel appears to be getting to the metering head as when I undo a union I can hear the pressure release and a little spray of fuel is released.

I assume I should be seeing a spray of fuel from the Injectors when cranking with the air flap held open? Does this indicate a faulty Metering Unit or blocked injectors because its not been driven much?

Thanks,
Pete.

 

I suspect a stuck plunger in the metering head. In old currency, it's a stuck carburettor float.

See what others say though, as I try to avoid K-Jet where possible!

 

Yea, its just a little spray as the pressure is released. This is from an injector line thats being loosened.

I did take an injector off the line and held the open line in a container but there was only a small amount of fuel delivered, definitely no pressure there. Could the CO adjuster screw restrict fuel flow rate so much?

If when I try bridging the relay contacts I still don't get any fuel would this lead to a faulty fuel pump or could this be the accumalator?

 

Well I have spent a couple of hours on it tonight but still getting no fuel flow to the injectors. Things I have tested are:

- Replaced Fuel Fiter

- Bridged the fuel pump relay with injectors in jars and connected the battery up. The pump is constantly running but still no fuel even when lifting the air flap. Removed injectors from lines and hardly any fuel flows from the lines either, maybe half an eggcup full from each. So I am thining the injectors may be ok.

- Removed the meter head from the air box to check the plunger but that moves nice and smooth and returns to its original position so no problems there.

- Loosened the fuel supply pipe, the one highlighted below and there was quite a lot of pressure there, nearly got a face full, lol. Pressure dropped after 5 seconds or so.


- Also checked resistance accross the WUR terminals and its bang on 20ohms with 12v accross the connecting plug when cranking (Tested as per the Haynes Manual). So this appears to be correct.

Does this indicate a problem in the metering head itself or is there any other things I should check?

Thanks,
Pete.

 

blocked fuel pump ? rust in the tank youd hear the pump but it wouldnt flow much fuel

 

There seems to be a good flow of fuel to the metering head as it seemed to release a lot of pressure when I loosened the supply banjo, but I havent got a pressure guage to test this.

I will have a look at the fuel pump and the in tank one anyway to check what you have suggested

 

on the metering head on one of the inlets (i have a pic somewhere ill try find it) there is a small basket filter that could be blocked,but if you took that pipe off and nearly had a face wash,your pump seems ok,plunger is free so sounds like the m/head to me
did you try the same method but with injectors off and just the lines in jars,never hered of all 4 failing but if its been sat a while who knows

 

Yea I tried taking off the injectors with just the pipes open in jars and hardly any flow, half an egg cup at most.

I will check the small basket filter , didnt know there was on in there. I did notice the fuel pump bolts had small filters in them so I guess its a similar bolt.

 

its actually inside the bolt/union,its a long shot but worth a look,you can take the metering head off the housing by undoing the three spline bolts to examine the plunger properly,you should be able to push it right in the metering head and it will come out slowly,im sure iirc the plunger isnt connected to the flap,so it could be the flap is free but the plunger is stuck,again worth a look for the sake of three bolts

 

Yea, I already removed the meter head and checked the movement of the plunger, all smooth and not sticking.

Fuel tank isn't all that full tbh, probably just above the red.

 

I havent put a voltmeter accross the lift pumps terminals but I did unplug the connector to the main pump from under the car and I heard the in tank lift pump running, so I guess its working fine. I might whip it out though to check for sure.

How can I check flow from the lift pump to the main pump?

Still doesnt explain why i'm getting fuel pressure to the metering head though if I did have a problem with the lift pump, unless this pressure is too low to supply the injector lines.

 

i suppose you could have pressure but low volume,bit like standing on a hose pipe,pressure there but no water momentarily,usually caused by h/p fuel pump failure,caused by lift pump failure,normally creating a very noisy h/p fuel pump however,my bets are on it been further up,i.e metering head area

 

Yea, the pumps don't appear to be too noisy, but I wont rule it out I guess. I will take another look at it tomorrow, starting with removing the fuel supply bolt on the metering head to check the small basket filter.

Thaks for all the suggestions! keep em coming if you think of anything else

 

Well I have removed the bolts to the fuel supply and return lines and they do have the basket filters in them, but all looks clean with no blockages. I blew compressed air through them just to make sure and it seemed free flowing.

Took off the 5th injector and re did the test but no fuel there either.

I happened to find an old metering head that came with the car when I bought it. The piston moved freely in this one also and I heard a small whoosh from the connector ports when I pressed the plunger in so it sounded like there were no blockages in this one. Anyway, thought I would connect it up and give it a try but still no fuel to the injectors [:^(]

It could be that both of these metering heads are faulty, and the old one I found was one that was replaced previously, so not sure where to go from here? I dont really want to go shelling out on new fuel pumps / accumalators if I can help it as I beleive these can be quite expensive new.

Thanks Rubjonny for the offer of the pressure tester I might try to test the flow supply from the fuel pumps first to see if I get the correct amount of fuel in a given time as I dont really know anywhere to get the lines made up.

 

its possible that other one is broke too and yes the high pressure pump will be over 100 pound and accumulator around 95 pound,so you dont want to replace them unless your sure,its a shame you cant borrow a known working m/head
have you done a delivery test,cant remember ff hand but think its 1.5L per minute,but as mentioned earlier it sound like your getting it up to the head,you said you nearly got a face full and it died down after 5 seconds,sounds about right to me

 

that sounds alot