ABF on K-jet - setting up & troubleshooting? Fixed and MOT'd!!!

The pulley only has one bolt that actually goes into the crank, the big one in the centre. So if the woodruff key shears, or rattles about a bit destroying it's groove. then you're bolloxed.

 

Just a little update to say that after lunch my brain function returned a little and I remembered the car has an oil pressure gauge. This is showing about 2 bar at idle and increases to 5 bar when revved with the engine hot, so I think the oil pressure it ok.

In that case I am confused as to why the light and buzzer come on when the wiring appears fine? Is this indicative of a knackered earth somewhere?

I tried setting the dizzy to zero degrees advance and running it like that. Once you set the mixture and idle to suit it runs ok reasonably well, makes less of a pinking noise when revved but still doesn't seem right and gets hotter on the temp gauge than I'd like.

Surely this must be a fuel starvation issue? Will a new lift pump sort it? Shall I remove that little filter from the metering head fuel inlet? Who knows!

 

Just skimmed thru this thread (had a few beers/ fri nite) how are the fuel injectors? I did similar diagnoses after rebuild on 8v k-jet withsimilar probs - checked this/ checked that, when eventually I diagnosed a fuel problem by swopping out the injectors and realising despite fuel pressure/spark/timing all good there was little if any fuel getting thru.... just something to check?? good luck!

 

Hi - thanks for the reply. The fuel injectors look okay and all seem to be getting fuel through them, in that they are nice and clean and smell of petrol when you pull them out after the engine's been running.

I haven't tried testing them for flow rates or anything like that though and notice that one is missing it's 'top hat' thingy on the end of it, but it's always been like that and ran fine on the KR.

I'm still wondering about that little filter in the inlet banjo on the metering head, sure I've never seen one on previous cars. That said, it's probably been there 20 years since the car was made so unlikely to be a problem all of a sudden!

Any more suggestions and ideas much appreciated. Think I'll just wait for the new lift pump now and try that next as the more I tinkered yesterday the worse things seemed to get!

 

Here's a (not that good) photo of the bolt in question:



1. Fuel pressure regulator on the left
2. Inlet fuel line bolt with filter in the middle
3. Return fuel line standard bolt on the right

Anyone seen one of these before? Should that little filter be there?

 

The inlet fuel bolt should have a filter so that is correct.
The return line bolt should not have a filter so that is correct too.

Gurds

 

At this point id be tempted to test the injectors. I did this by taking the lower intake manifold off and flipping it upside down, resting on the engine. then put the ignition on and lifted the metering head flap by hand. You will then get a shower of fuel squirting out and plents of pintle chatter. Obviously this is a big fire hazard so make sure the engine is cold and your not smoking a fag. People will go mad about doing it this way but its quick, easy and saves making a rig to hold jam jars! Just be careful!

If thats ok id start at the begining with the timing. take spark plug 1 out and set the piston to top dead centre by feeling with a wooden dowel of wood down the hole. Once you can feel its at the top you can also check to see if the flywheel mark matches. That done id next line up the top end by lining up the cam pulley with the V on the cam cover, id then whip the cover off and check the inter cam timing dots and also the position of the 1st lobes on each cam (should be like / \). Id then whip the dizzy cap off and make sure the arm is lined up with ht lead 1. That done id put it all back together, start it up and set the ignition timing with a light to the 6deg mark.

fingers crossed.

 

Another simple ingition test, swap over the dizzy too if you havent done so already. Had these fail on me in the past too.

Gurds.

 

Thanks for the replies lads, so that little filter is supposed to be in the inlet line eh? Perhaps my other car did have one after all and I've forgotten?

Good suggestions on further troubleshooting, will try them in due course when the car is back in some kind of working condition after last nights issues...

So, last night I fitted a new lift pump...




Then located a tried and tested fuel pressure gauge and various adapters to be able to connect it up to see what was going on pressure wise. First I removed and drilled the back of the WUR in case it needed adjustment via the 'hidden' allen screw.






Once that was done and the gauge was all hooked up I got the car running and warmed it up to normal operating temp and a reasonable idle. I connected the gauge into the line from the centre of the metering head to the WUR, that's correct isn't it?

This is the control pressure at warm idle - rather high at 4.2 bar (60-odd psi)!




It seemed to get this high very soon after starting, around 30 secs or so I'd say, which is incorrect. As I recall the pressure should rise slowly and smoothly over about 90 secs from starting up to a max of 48 psi.

So, I tried to adjust this using the allen screw in the WUR but it was having none of it and stayed at that pressure - makes me think the WUR is knackered.

Anyway, next I blocked off the end of the gauge as it doesn't have a shut off valve, to read the system pressure at the metering head. This came out as this - approximately 5 bar, which is correct and means the fuel pumps are doing their job ok I think.




By this point, around 9.30pm I was quite happy thinking that I'd found the culprit of the running issues was the WUR. I came to dismantle the gauge and lines and firstly stripped the thread in the gauge t-piece, and then managed to snap off the adapter into the centre line of the metering head!

I'll go to the local Pirtek place today hopefully and see if they have anything suitable to fix it with as without those parts I can't do anymore testing, and can't actually connect the fuel lines back up!

Anyone got a spare good WUR?

Thanks for all the help so far, feel like I might actually be getting somewhere with this now - all hail the fuel pressure gauge!

 

Forgot to say, am I correct in thinking that the higher the control pressure the leaner the mixture?

I would have thought so as the control pressure starts low with a cold engine (rich mixture required) and then as the pressure goes up with engine temp the mixture leans out. So with the control pressure too high, as in my case, will the mixture be too lean thus causing the pinking and running issues at higher revs?

 

keep going mate.

most people would have blown the thing up by now

 

Cheers, I'm nothing if not persistent!

Have to admit though, if there happened to be a steep cliff in easy pushing distance of my house the car would be off it by now! I've been through the stage of hating it, now I just feel sorry for the thing!

 

Yup, high control pressure = leaner mixture and hence the pinking etc.

I think the desired pressure is 48psi/3.3bar ish but double check the figures.

Gurds

 

Bloody hell Stu

 

Might be onto a winner there. Good trouble shooting that man!

 

Setting fuel pressure.

http://www.clubgti.com/forum/showthread.php?t=81658

 

Ok, thanks for confirming - does sound like the excessively high control pressure is my problem then.

I know!

Cheers - hopefully getting there now!

Cheers Mike, much appreciated.


Right, today I've not made much progress but got a few things sorted. Firstly I went to the local Pirtek hose and fittings place and they were able to fix the t-piece on the pressure gauge where I knackered the thread so that's up and running again. Good news.

They didn't have anything suitable to fix the threaded union where it snapped into the metering head - please go and raid your garages / sheds and if you have one of these spare drop me a line!

Wanted ad here: http://www.clubgti.com/forum/showthread.php?t=165238

It's this bit... but in one piece obviously!




Goes here between these two fittings:




Also after a good WUR if anyone has a spare too

 

I was wondering if I could fix the apparently knackered WUR so thought I'd take one apart to see what's inside. This is an old spare one that was problematic on my other 16v so I replaced it years ago - hence didn't mind taking it to bits...




Turns out there are a lot of bits once you start...!








I'm not sure what could go wrong with one to be honest, presumably the springs could be worn or out of alignment, heater knackered, bi-metallic strip not bending as it should, fuel connections blocked or mechanism bunged up?

Any ideas? I might take the other one from the red car apart and see if I can see anything obvious but doubt it'll be straightforward to fix as it probably just looks the same as this one inside!

Thanks for reading, hopefully once I get these parts and put it all back together (without snapping anything else) I will be able to report that the car works properly at last!

 

Id probably guess faults would more likely come from that plunger bit sticking and not moving/adjusting freely.

I also know of this site which explains what everythink in the k-jet setup does. May help.

http://www.auto-solve.com/mech_inj.htm

 

The heater element does go, but you can test for that electrically.

What does the allen screw in the back (the WUR Mod one) act on - is it the end of the bi-metal strip?

I suppose if the metal strip work-hardens over the years, then it could change the way it controls fuel pressure. I'm guessing though. Maybe it loses some of its springiness?