K jet experts required

I recently bought a  83  golf gti that had been partislly restored by the previous owner,.basically when I collected it he mentioned the idle was lumpy.
the car has been re built including all the fuel system except the injectors and accumulator.
anyway I have had the car re sprayed and then started on the engine.
i set up the ignition timing and co but it was still lumpy. It was much worse when cold, once warm it wouldn't rev if you mashed the throttle. If you built the revs up gently it would rev clean from 3k to red line but hold back at lower revs.
i checked the injectors and the pattern was poor. I replaced all 4 and the seals. It was still a little poor when cold but idle was smooth and was revving cleanly. The only issue being that if it stood for 20 mins it would have to crank over a while before re starting and the idle was low to start with then would pick up.
I could smell fuel so looked at the accumulator and it was leaking from the screw. I thought that was the likely cause of poor hot start. Knowing it would fail the mot I replaced it with a new Bosch one.
however now the car won't start. It will crank over and run lumpy for a second then cut out.
it has also been back firing from the metering head boot.

i am pretty competent with motors but this has me stumped. There is plenty of pressure from the fuel feed to the metering head.
how've veer when I undid the lines to the injectors  on the metering head they fizz as though full of air.

i undid the large union to the wur and there's loads of pressure there too.

im a little stuck now as I'm getting no where, the tank,lines, pump, accumulator and injectors are new but it seems worse after changing accumulator.

is there anyone in the Worcester area who knows their stuff and prepared to cast an eye over things for me?? Please!

i'm not an expert but have messed with a few!

Your original issue where it took a while to start after being stopped for a period of 20 minutes could be down to fuel pump relay not priming the system after the pressure had fallen away during that 20 minute period.
As for not starting since changing the accumilator sounds like an air lock. your 5th injector is causing the engine to run for a couple of seconds. You could try disconnecting the electrical feed to that and it may allow you to crank it for longer or bridge the relay to the pump so the pump runs for a decent time to clear any locked air.
Popping back to the metering head sounds like its weak as well.
I don't think you can get the pipes connected wrong on the accu because the threads are different if I rememember.
Failing that you may need a pressure tester

i iinitially tthought it was air in lines. 
however its been tturned over loads so would have expected it to have cleared.
with the 5th injection off it doesn't  even try to fire. i need to the test the pump again by bridging relay. 
is there anyone in worcester who can help. iI'll pay beer tokens.

ps you cant do lines to accumulator wrong as they only fit 1 way.

What if you bridge the pump, take the top off the metering head and lift up the flap by hand to fool the head into sending fuel to the injectors?

You might want to pull the injectors out the head and put a jam jar round each one so you don't fill your cylinders up. At least you cvan see fuel coming out the injectors an remove any locks there.

thanks ill give it a go. does anyone local have pressure testing kit and know how to use it?

well i bridged the spump relay ttoday. plenty of pressure to meter head. lifted flap and no fuel to injectors. any ideas!.

Have you loosened the pipes (or at least 1) on top of the metering head that goes to the injectors?

If you're not getting fuel from the loosened pipe it could be the metering head plunger stuck or possibly an issue with the WUR.

If you do get fuel out the loosened pipe it could be that your not reaching the required system pressure required to open the injectors - either pump issue or primary regulator fault (inside metering head)

When you have fuel pressure does the flap feel different to lift ( a different resistance) to when there is no pressure.

The plunger has a governed fuel pressure supplied to it from the WUR (control pressure) which alters the ratio of plunger height to flap height depending on whether the engine is warm or cold ie. provides a richer mixture when cold.

The plunger is an accurate piece of kit which can be effected by dirt in the fuel or even by the residue left when old fuel has evaporated off ametering head which has been stood around for a long time.

i oopened an injector line it fizzed as though blocked. i opened the feed line to the wur and there was loads of pressure. does it look the metering head is faulty?

Take the plunger out of the metering head and inspect it for rust and crud. The four slits in it that allow fuel to pass to the injector lines are very thin. Any signs of rust means the metering head is scrap - this will off been from water in the tank from a rusty filler neck at some time. Unfortunately you may have filled your nice new injectors with crud, and they are very hard if not impossible to clean (they open under pressure, so cannot be reverse flushed).

monkeymagic said

i oopened an injector line it fizzed as though blocked. i opened the feed line to the wur and there was loads of pressure. does it look the metering head is faulty?

Fizzed with fuel?
It will have pressure locked in it as it takes upto 45psi for the injector to open. Anything below that and it will stay in the injector line so will release pressure when you crack the bolt.

Hi just a quick one do you know you have the timing set at top dead centre with it back firing and all ? You probably have set this correctly but there is two marks on the cam pully and could easily be set 180 degrees out, just something to check off your list hope this helps.

it fizzed as though it was restricted. there is loads of pressure from feed line. i timed belt with punch mark aligned with head. when it ran for 5 mins ran great. doubt injectors blocked though.

monkeymagic said

it fizzed as though it was restricted. there is loads of pressure from feed line.

yes it will be restricted because you are down stream of the metering head at that point.

You really need to connect a pressure tester to see what psi you have.
If you have a new pump then yes there will be loads of pressure from the feed line. Probably about 70psi but if the primary regulator inside the metering head is faulty then you may be getting less than 45psi at the injector pipes. Enough to make it fizz but not enough to be opening the injectors.
I don't understand myself why changing the accu has caused this much bother though!! I keep thinking its something daft but then you bought it like it and you don't really know its previous I guess.

I have a good metering head here in Banbury (about an hour from Worcester) but I lent out my spare WUR's to Ginner in Cov so don't have a spare one of them you could try.
I don't mind coming over with the head one night this week- it's doing my head in now as well!!

Yomp you are a star. I work in Stratford and leaning ton so would happily meet up to save you the travel.
Does the fuel go to the wur then to metering head then injectors.? The car had been behaving odd since I bought it and I suspected the wur. I now wonder if the metering head is clogged. The only parts not replaced were the metering head injectors, accumulate and wur. I have done rather accumulator and injectors since.
Every time I set it up it would be fine til it next fired up and it would be all over again

The fuel from the WUR is only used as a hydraulic fluid to control the plunger height ratio. In theory if the plunger had no leak between itself and its housing none of the fuel which ends up inside the WUR would ever get consumed by the engine.
The fuel taken off from the metering head to the WUR and its pressure is taken from the primary regulated pressure which is constantly governed by a valve in the metering head.
The return from the Wur then goes back to the metering head and the WUR governs the control pressure to the plunger. As the WUR warms up from cold, the pressure to the plunger increases making the mixture weaker (as required by a warmed up engine) This is why the WUR is bolted directly to the block. Its heated firstly by electrical power but then the heat from the block takes over so a hot start is possible.
If your primary pressure is wrong then your WUR pressure will be wrong as well. The primary pressure is controlled by a spring loaded valve and shims deep inside the metering head.

The air flap lifts as air flow passes through the system as you open the throttle or as the engine demands more air. the flap, as it opens, pushes on the opposite side of the plunger to that of the control pressure and allows more of the primary pressured fuel to escape the metering head via metered slots to the injector pipes thus increasing the fuel amount relative to the amount of increrased air being consumed.

As Lhasadreams mentioned earlier these cars suffered with the fuel filler necks rotting. Rust, cr*p and water get into the tank and the system. Even though there is the fuel filter some of the foreign objects and especially the water gets inside the metering head and can start to damage the sensitive parts within the metering head that control the plunger and the primary pressures.

I'd rather come over and see it for myself rather than just lend my bits out tbh. PT your postcode and I can see where you are. As i said I might be short of any spare WURS at the moment though. I might have one I just need to have a dig around my lock up.

Okay mate that's very informative. I know the cars suffer with fuel contamination and suspect like many others that this is the cause of mine,
The car is in my shared unit at my mates classic car place Worcester Classic cars post code wr7 4qp. My name is Steven and my mobile is 07734441065.
thanks again. 

I'm still having problems with this car. I replaced the metering head and it's made no difference.
as far as I can tell now the only part that hasn't been replaced is the wur.
Does anyone know of any specialist k jet knowledgable garages in Worcestershire west midlands area..?

Vince and Stealth Racing - famous for the WUR mod and fitting K-star in years gone by.
Stealth Racing UK

Thanks mate ill tthem a call