k-jet problems

ok tryed taking it apart and found the plunger moves freely. tryed to lean it off abit but still made no diffrence. when priming the pump no spray. but when i lift the flap there is a spray and the number 2 still sprays a light jet of petrol after the others have stopped.swapped the injectors around and still number 2 lightly sprays. so i either need a new metering head or a full set of injectors again.

fact the problem remains on injector number 2 after you swap them all around suggests its a metering head problem

thanks for your help dude getting another metering head hopefuly on sunday.? fingers crossed it helps.



 :mrgreen:

ok metering head made no difference. this morning the car ran on three cylinders..

seems to be realy bad when it is cold. any one know of ant 40's and manifold going cheep?

                       

rubjonny said

fact the problem remains on injector number 2 after you swap them all around suggests its a metering head problem

scotdub said

OK got a brand new set of injectors

This aint adding up. I think you need to approach it in a different way. I'd be measuring the mixture at different running conditions, to start with.

It is confusing me so much. was running perfect had the co set and new injectors then just started playing up. runs good when warm but is a nightmare to start have to rev the engine to about 3000 rpm untill it is warm then pull off. the spray pattern is good with the flap open but the number 2 injector still sprays like 6 jets after the rest have stopped spraying. swapped the injectors around and still no 2. im so confused.

scotdub said

It is confusing me so much. was running perfect had the co set and new injectors then just started playing up. runs good when warm but is a nightmare to start have to rev the engine to about 3000 rpm untill it is warm then pull off. the spray pattern is good with the flap open but the number 2 injector still sprays like 6 jets after the rest have stopped spraying. swapped the injectors around and still no 2. im so confused.

Swap the fuel lines on the metering head around, if the problem stays on the same output line on the metering head there's a little tweak you can do to equalise them out. But then you've fitted another metering head, right?

And don't forget, every adjustment you make, needs a reset of the basic mixture setting.

i still have the old unit. what is this little tweek?

will try and get the garage to set the co again with the new unit then if thaqt don't work will try swaping the lines over and see. Thanks paul.

would redex damage the injectors atall?

gary

OK got the co set yestarday. runs better but still got the engine dieing in the morning unless it is revved.
do you think the wur is faulty or am I just trying to change things for the hell of it.

Check out this link, there are two pdf files you can download towards the bottom of the first page. These may help you test the individual components, they certainly helped me understand a bit better how the system works.

http://www.vwgolfmk1.org.uk/modules.php?name=Forums&file=viewtopic&t=47763

these 2 are worth a look also 1st one is a volvo guide but most if not all same as VAG:
Google Sites: Sign-in

Bentley guide on pressure testing the k-jet system:
Google Sites: Sign-in

Dont forget I have that pressure guage if you want to check the pressure!

Take MK1Allan up on his offer.

Seriously the only way to fault find a k-jet system is by measuring the system and control pressures first.

All k-jet is, is a set of mechanical pressure differentiators, one in the WUR and one for each of the injector lines  - ( there is a way to tweak them at the metering head, that is what Paul_C was on about).

So firstly you must have good system pressure otherwise the injectors will not open properly and the control pressure will be out (the WUR sets this).
Low system pressure could mean a knackered pump, high system pressure could mean that there is a blockage in the fuel return line - there is room for some slight adjustment at the metering head by adjusting shims.

Next from cold measure the control pressure, the WUR alters this through warm up, it is the pressure that is exerted on the top of the metering head plunger, less pressure when cold allows the plunger to move more for a given amount of air demanded by the engine, ie a greater fuel to air ratio (like a choke on a carb), as the engine warms the control pressure will rise and lean the mixture until it is spot on for warm running. The control pressure must rise smoothly, it is warmed by the engine and a bimetallic strip inside the WUR - if it is does not rise smoothly or the warm/cold control pressures are out then the WUR is knackered. It can be separated and the pressure differentiator can be cleaned - I have had mixed success, but checking the control pressures will confirm or not.

Next whip the injectors out and put them in jam jars, run the pump manually and lift the metering flap until you have a measured quantity of fuel in one jar, compare this to the others to ensure even delivery. Low delivery indicates worn injectors, partially blocked metering head slits in the plunger (rust !!!) or worn pressure diffentiators.
Empty the jars and leave the injectors over night in them, there must not be any fuel drippage - otherwise the injectors are knackerd, a very common fault for poor running from cold as the excess fuel in the cylinders is dealt with !!

You will also want to leave the gauge connected when measuring system pressure, it should hold up for several minutes after switching the engine off, if it doesn't then either the check valve on the end of the fuel pump of the accumulator is knackered.

Another common fault is that the fifth injector runs continuously, whip it out and put it in a jam jar to check, either a fault injector or a knackerd Thermo Time Switch.

Finally you need to get hold of a gas analyser - I have a cheap and cheerful Gunson one, you cannot setup k-jet properly with out one.

Hope this helps

thanks for the info dude.

will get the tesster of allan and he can help me work it one night.

Have replaces everything except the thermo time switch and 5th injector. have 4 new injectors a new pump fuel lines filter secondhand metering head with made no diffrence secondhand wur new tank and a good filler neck. am kind of thinking maybe it is the wur or the thermo time swith just is realy bad on start up but runs great when warm. idles perfect and revs free.

cheers

gary

I have a gunson gas analyser too! Will have a look at it one night I,m sure its something simple, its got to be because almost everything it new!

You can eliminate the thermo time switch simply by pulling the connector off the fifth injector, it only runs the injector for a max or 8 seconds, so has little to do other that get it fired up quicker.

My bet is that the WUR has either a low control pressure when cold, making the mixture too rich or a high control pressure making the mixture too weak.

The gauge will confirm or deny.

Failing this you may have mixture set incorrectly on the metering head (hex dowl adjuster) that is compensating for a crap WUR.
So be sure to get the control pressure spot on (warm and cold) and then set the CO - remembering that this sets the mixture adjustment throughout the rev range. K-jet has a tendency to run leaner higher up the rev range that is why some people set them up richer at idle to gain more power higher up the revs while sacrificing some economy !!

This is where a rolling road setup would get you the best setup across the rev range - I use to run a k-star which allowed finer fuel and advance/retard adjustment across the rev range - allowed me to run 95 ron without a noticable loss in power or pinking - yes I was being tight and should of run super….

I doubt that it is anything electrical as it is ok when it is warm, having said that cracked dissy caps can cause problems like you are seeing, start it up on a dark night and look for any signs of arcing around the cap !!

Good luck !!