1.8 DX K-Jet fuelling issue

Afternoon all!

We've got a forum member's, '86 Cabby in for recommissioning and have a fuelling issue that needs sorting. We've already sorted a lot of other issues along the way, like flushing out the fuel tank and lines from old crud (assuming from an old filler neck that has been replaced) but still have some issues.

There's some areas we want to check now but would be grateful for opinion or comment, especially if anyone has had the following problem.

Firstly info;

- The whole metering head is new/refurbished along with warm up regulator
- Fuel pump and accumulator have been replaced to test with known working units and no difference
- Fuel filter replaced
- Three fuel pump relays tried - two new and one used known to work

The problem;

- Having sorted out a sparking problem (new dizzy) the car wont start - it's getting no fuel at the injectors.
- The fuel pump does work - lift pump too.
- One quirk of the car, is the pump doesn't prime when you turn ignition on, but makes the priming noise at the end of cranking before turning the ignition off! Fuel does flow out of the pump when you crank the engine however. The owner had a short behind the dash previously which fried the pump (now replaced) and some other issues. Since this time the pump doesn't primer we're told. Randomly, twice the pump has primed when turning the ignition on. We need to check back the wiring on this still.
- If you put permanent 12v on the pump the engine still wont start as no fuel at injectors again
- We fitted a spare injector and hose to the metering head (four injectors left in the engine) and stuck the spare in a bottle to get an idea of what's happening. On cranking there's no fuel at the injector. However, put permanent 12v on the pump and lift the air flow plate on the metering head by hand, and it sprays fuel very well.
- There's no obvious splits/leaks in intake or vacuum pipes - obviously would be easy to check if the engine would start!
- It seems that the air flow plate wont rise enough on starting to let the fuel out to the injectors.

Solution;

- That's about as far as we've got. A 16v servo has been fitted to the car - if this has gone bad (the car has only run about 20 minutes with the owner with the car as-is) would this be the issue - i.e. not enough vacuum so air flow plate wont rise on starting?
- As mentioned above, we need to trace back the pump wiring, to explore why it doesn't prime - but it does deliver fuel on cranking.
- Visual checks only of fuel flow and pressure so far and both appear to be very good now.
- There's no blockages anywhere and everything has been replaced, metering head was refurbed unit from KMI and air flow plate is set correctly

Any ideas anyone?

Thanks in advance
Andy

Anyone?

rubjonny ?

If the fuel pump relay is a VW one and no.62 it won't prime as mine does not as that's what they are suppost to do.
Have you tried bridging the 2 bigger connections with a bit of wire to get the fuel pump running all the time? By the sounds of you have but I don't know why it's not starting…….

Hi Mark

Yes there's a permanent 12v feed set up to quickly plug in when needed. When the pump is running off that it still wont start and no fuel at the test injector when trying that.

Bert any ideas??  

have you checked if the lifter pump is working? you shouldnt see fuel put the injectors unless you lift up the metering head flap in case you didnt know, have a look thru this thread and just ignore the 16v specific bits:
http://www.vwgolfmk2.co.uk/forum/viewtopic.php?f=37&t=25972

Hi John, thanks for the info. Yes lift pump is working ok.

I've been through most of the basics - I'll check the pin in the metering head. You would assume it's ok as the unit is brand new/refurb from KMI but it wouldn't be the first time new parts don't work!

may be the airbox flap position then, bit of a pain to check its in the middle got to remove and hold it up to the light so you can see the light shining all roudn the edge!

rubjonny said

have you checked if the lifter pump is working? you shouldnt see fuel put the injectors unless you lift up the metering head flap in case you didnt know, have a look thru this thread and just ignore the 16v specific bits:
http://www.vwgolfmk2.co.uk/forum/viewtopic.php?f=37&t=25972

you know your stuff rubjonny but how does the car start without fuel does the flap lift as your cranking engine without touching the gas pedal??
if so when you turn the key and the pump primes your saying their shouldn't be any fuel from injectors
guess my jectors are duff or the flap/mixture screw needs setting right

hope you don't mind me asking questions
I'm setting mine up at mo and the injectors drip/weak spray when the pump is primed
is it new injector time or can I adjust them with the mix screw in the metering head

Does your car start ok but is a little lumpy on tick over when 1st started?

yeah sometimes
checked the accumulator good
checked the non return valve good
tweaked the spring clip on the metering head flap ever so slightly to stop the injectors dripping
cold start valve good
timings good
aux air valve works
only thing ive not touched is the warm up reg maybe its not getting enough fuel when cranking but there seems to be enough coming from injectors when cranking
 
    

vacuum from the engine will lift the flap, and you get fuel. on a cold engine the 5th injector is also there to help. This is another reason you dont want any vacuum leaks in the system, the flap wont lift up as much

if the metering head allowed fuel to be injected when sat at rest, it would flood the car every time the fuel pump primes

Fuel injector tests are covered in my guide above, if they dont drip and spray pattern is good then its not injector fault. Its worth making sure on a hot engine the injectors dont leak as well as when cold. Same test put them in containers, jump the relay and lift the flap all the way up and release, make sure no drips

with WUR and non-return valve plus accumulator only real way to know is with a set of fuel pressure gauges, or make an educated guess and swap parts to see if problem solved. No telling if the new ones are any good if used parts though, unless you have a set of fuel gauges

rubjonny said

vacuum from the engine will lift the flap, and you get fuel. on a cold engine the 5th injector is also there to help. This is another reason you dont want any vacuum leaks in the system, the flap wont lift up as much

if the metering head allowed fuel to be injected when sat at rest, it would flood the car every time the fuel pump primes

Fuel injector tests are covered in my guide above, if they dont drip and spray pattern is good then its not injector fault. Its worth making sure on a hot engine the injectors dont leak as well as when cold. Same test put them in containers, jump the relay and lift the flap all the way up and release, make sure no drips

with WUR and non-return valve plus accumulator only real way to know is with a set of fuel pressure gauges, or make an educated guess and swap parts to see if problem solved. No telling if the new ones are any good if used parts though, unless you have a set of fuel gauges

that's what I thought the process was when the engine cranks over drawing air in though the intake it pulls the flap up and then pressure is released from metering head to injectors
thanks rubjonny your the man
I recon the wur is the next inline to get a good clean hope that will help
thanks again