K-jet pressure test results - help

OK I think I have cracked it!  

I had a day off today, and my new o-rings arrived yesterday, sun was shining, etc etc.

So I changed the small o-ring on the primary regulator and ran the tests again. No change on system or control pressures (still on the low end of acceptable), but residual pressure was much better - not dropping like a stone, but still not holding as long as it should. But I did see the effect of the accumulator - engine off the pressure drops and then rises again. I ran a test again on the incoming fuel and it held pressure for ages, confirming the NRV was OK. So, back to the PPR. I found a shim the right size and .45mm thick. I removed the PPR (for the second time today) and the larger o-ring fell out in 2 pieces! This o-ring was also very new. So I fitted a new one a size smaller, as well as the shim. Pump on, and system pressure has increased to 4.9 bar. Engine still a bit reluctant to start and run, I think it will need a tune as I have had to fiddle with the mixture and throttle adjuster. Eventually get it running and the WUR behaves perfectly, rising from 1.2 to 3.5 bar in less than 5 minutes. I notice that the engine takes longer to warm up to fan-on than before -  I will take that as a good sign. Once it is nice and warm I switch off and pressure drops to 2.8 bar, and 10 minutes later it is still at 2.75 bar - woohoo. I start the engine again and it runs first time   I have ordered some shims so I can increase the system pressure a bit more, plus copper washers as the fuel filter banjo is weeping slightly. After quite a few false dawns where I think I have sussed it, I finally have - and couldn't have done it without all the help and advice from members on here - plus some useful threads on sites like vwvortex and clubgti. For anyone that needs to change their PPR o-rings, the sizes are 3.68mm ID x 1.78mm CS for the tip and 6.78mm ID x 1.78mm CS at the other end - I used viton.

Hopefully this means some summer motoring at last (I have had the car 5 years).

Lee

excellent news

Update - the shims and copper washers arrived so I have been tinkering a bit more. Added 3 x 0.3mm shims, which brought system pressure up to 5.3 bar, at the top end of the acceptable range and residual pressure is holding perfectly now there are new copper washers o the fuel filter outlet. Looking forward to a run out at the weekend, give it a bit of a blast!

thanks again to all for the help and advice.
Lee

Well done LeeO and thanks for sharing it with us. its on here forever for future generations to scratch their head over!
I managed to clean my WUR filter out without having to remove them. Although I did strip it down to the diaphragm and then blew it with compressed air in the opposite direction to the fuel flow to clear it and then put it in my ultrasonic cleaner for an hour. I'll swap it back onto the car at some point just to check it. I'll know I have a good spare then.
I also stripped out the metering head with the sticking plunger and ultrasonic cleaned all of that  while it was in bits. I never had any broken O rings so I've just reassembled it and the plunger seems fine now. Again I'll test it on the car it came off and if its OK then it can stay on as its the original one to the car. Fingers crossed!

Fab news on the work you've done  Would you be able to upload a few pics & point out what exactly you changed (For the non-abbreviated understandables among us - being me )

I need to get the mixture right, it's running rich & smelling of fuel… but i'm not having much success in finding a garage with somebody capable to do a tune without a plug in diagnostic answer to most things!!!

Cheers. 

Yomp - the fine debris in my WUR filter wouldn't shift without splitting the gauzes, it was very fine and grey debris - those gauzes are a very fine mesh!

Deanandubya - I haven't got photos of the key moments, but I will post links to other photos and articles I used that will show what I did (lots of googling while I was researching the problems):

WUR stripdown step-by-step: http://ferrari400parts.com/Warmupregulatorrepair.php

Fuel distributor: http://www.cabby-info.com/Files/CleaningFuelDistributor.pdf

Primary Pressure Regulator: http://workshop-manuals.com/volkswagen/golf-mk1/images/golf-mk1-783.png
http://www.specialtauto.com/delorean-parts/images/fuel-prim-pressure-reg-plun.jpg
http://forums.pelicanparts.com/porsche-911-technical-forum/620037-cis-pressure-regulator-pics.html

Fuel delivery test: http://www.mk1dubz.com/pdf/Testinjectors.pdf (I used plastic water bottles and duct tape, and relay 17 instead of making a jumper and switch)

Fuel pressure testing: http://www.mikegabriel.net/vw/badhabitrabbit/fpressure.html and Rubjonny's guide on the Mk2 forum

This old article was useful as well: http://mastertechmag.com/pdf/1988/10oct/198810IS_KJetricks2.pdf

I hope this helps - if you need more, let me know.

Lee

The Primary Pressure Regulator sets the system pressure, by controlling when fuel is allowed to return to the tank. The higher the system pressure the more fuel comes out of the injectors.

If your system pressure is low - or if your WUR isn't working properly, it won't run right. On mine, the WUR was completely blocked, so the control pressure was the same as the system pressure - 4.5 bar of pressure pushing down on the plunger, which makes it harder for the plunger to lift and let fuel to the injectors. Cold starting was a real nightmare. I guess if your WUR is partially blocked, control pressure would be higher than it should, which could be compensated by giving it a bit of extra throttle. The electrical tests don't tell you anything about whether the WUR is controlling pressure properly - unfortunately only a set of pressure gauges can do that. If it is just in need of a tune (like mine is), then you need an exhaust gas tester (I am hoping to borrow one from a mechanic friend). Perhaps get it tuned first, and if that doesn't do it, it will have to be the pressure tests.
Does that help?
Lee

No worries. Even my mechanic friend - who works on all sorts of cars, didn't have a k-jet test kit. If the tune doesn't sort it, maybe put a call out for an OC member near to you who has the kit - if you are near West London, I would be happy to.

Hi,
Ok, yes, relief valve is another name for the PPR. I measured the shim size as follows:
the baseplate that the big spring pushes against is 9.9mm x 5.3mm. I measured the big spring as 7.68mm x 5.5mm. So the shims need to have an ID bigger than 5.3mm, and an OD no bigger than 9.9mm. I had one correct sized shim, so I bought these: http://demonpowerproducts.co.uk/product_info.php?manufacturers_id=164&products_id=5828 and fitted them between the baseplate and the correct sized shim. Having a range of thicknesses is helpful for making quite small adjustments. The supplier was really quick.

O-rings - ebay or polymax.co.uk (but they have quite a large minimum order) - get viton rather than nitrile if possible, it is supposed to be better when used with petrol.

Copper washers - I bought a selection pack from ebay, but some of the vw copper washers seem to be non-standard sizes - the new washers I fitted to the fuel filter were a bigger OD than original, but still gave a good seal. To be honest, I have only replaced the copper washers on the fuel filter joint becuase I couldn't stop it weeping - I have reused existing everywhere else, and had no leaks.

Let me know how you get on.

Lee

All sounds good - but just one thing - to remove the PPR it is the 16mm hex head bolt you unscrew - the allen key is for a small plug to another chamber inside the PPR. You can undo this as well if you want, there is another o-ring inside which apparently hardly ever gives any problems, so I left well alone.

hope all goes well

Hey Lee, fitted new gasket between Meter Head & air box on the weekend, stuck to the Meter head, gave it a bit of persuasion to get it off.. the underside of the Air Flow Sensor plate was a bit carbed up, surprised at this so gave it a blast with Inj/Carb cleaner & cotton cloth too.. Going to attempt the WUR tonight (if i can get it off) then have a go at the Meter head/PPR maybe tomorrow (easier job i think) see how the time goes… here's the old one.. bit on the flat side

 

Thanks for the update. The WUR is held on by 2 allen head bolts - much easier if you have the adaptor to fit hex head bits to a ratchet set than using ordinary allen keys.

When undoing the braided hoses watch out for those copper washers  - they love to drop off the banjo bolts into the depths of the engine bay  

No o-rings between WUR and block. The screws that hold the WUR together are tight, I had to use an impact driver on one of them - I think that there is thread lock used on them.

Man. this ain pretty!!!!!  Got the local garage to undo the bolts for me  got home, went out for a ride on my bike… felt pretty good, got back had nosh then attacked the WUR… took it apart & hey presto:-


Safe to say i think this is where my problem lies!!! will still put new o'rings on the PPR too.
Quite disturbing how the WUR has got like this! Cleaned the outside as much as i could. Undid the bolts & opened it up, pretty straight forward really… The spring & plate, gave this a clean, the bolt for the heater element no prob, took this off & cleaned up.  just really careful when i came to the base plate screws x4, put some Plus gas on these to settle for a bit, a bit of pressure & they unscrewed fine… very fine thread to these, carefully took the 'plate' off & it was a mirror type effect on the opposite side, cleaned this with carb/inj cleaner & cloth. also the plate 'attached' at the base & around it. Got a wire brush on the screws 'heads', nuts & washers. Also had a go at the filters as much as i could… The rubber seal in between the WUR housing itself is corroded so not worth treating, will get a new rubber strip for this.. So gave the main part of the WUR a good detailed clean, just need to do the back plate tonight.. (couldn't finish, the wife called about 9ish  otherwise i would continue until it's done..)
Even though i tested the WUR electrically it just goes to show that 'you can't judge a book by it's cover'… 

Below is one part finished, looks a damn sight better 


 

Wow, that looks pretty bad - perhaps the sealing strip had failed, letting in moisture? On mine, although the gauzes were completely blocked, the rest of the inside was absolutely spotless!
There are rebuild kits available from here http://www.ferrari400parts.com/catalog/ and I think on ebay.

hey Lee… managed to sort the WUR out, got a new seal fitted… fitted it to the car, changed the PPR rubber on the inner part, that was pretty flat, felt the outer had a good connection when it slid in the FD. Got the meter head off - dirty! 1 screw was a bit stubborn… the Plunger was moving freely, cleaned around it & put a new washer on/around. The air meter was dirty itself so cleaned that too… connected it all back up, torqued up… then the last thing, the return injector from the WUR to the top of the meter head, tried to tighten it to 10Nm & it broke/snapped!!!!  gutted!! I was so looking forward to starting my car with the work that had been done! I even went to VW with the part#063133541 '8x1/12x1.5 connecting bolt' & they haven't done them since 2012… so i got to try & get one from either on here or abroad, put it on parts wanted… the search is on!!!


 

Oh no, great progress and then that happens. All the rest is looking good - hope you find the part soon - the sunshine is coming

its the same for all kjet pretty much so you shouldnt struggle to get one at least!

Update!!! checking eBay for Mk1 Meters etc - bling bling! 'well polish my nuts & serve me a milkshake'  (American Pie quote there sorry..) just bought a FD on Ebay for £25… the guy wanted £40, offered £20 1st.. the post was £3.40, he counter offered for £30 so i replied with £21.60.. he accepted  boom.. seen the bolt & took the dive… 

As per my update in 'Cold Start Splutter for 20-30seconds…' I've made huge progress… The car is running more responsively with no hesitation. I basically stripped the Air Flow Meter from the Fuel Distributor, bought a bottle of CRC - Air Mass Sensor cleaner, had all the attributes to clean the system as they recommend Injection cleaner not to be used as it 'sticks' ?? so cleaned the Meter sensor throughout, dried/wiped it, connected the sensor to air box, FD bolted to that then injectors connected & torqued along with the vacuum pipes… turned it over & it started well, getting the air out of the system then it was fine. Took it for a drive for a couple of hundred yards & it felt good!!! So the WUR 'service' with the clean & new rubber seal, the 'o' ring & .3 shim on the PPR seem to be working!!
So, after taking it for a spin for about 10-15 miles i got back onto my drive… as it was idling it was going low, normal, low, normal & so on, this happened as well when the fan came on… so i think as it's running good, if you like, it needs a tune as it was running rich before so i'll get it in in about a week or 2.
If you think otherwise with the idle issue let me know..
apart from that i'm really happy how it's running - as the old saying went 'pocket rocket' Yesterday (Sunday) had a drive in the morning, driving crisp & sounding sweet… MPG massively improved as well… mid 30's no probs.. went for a blast last night too… took my time, even though the car felt like it wanted to have a play… nice clean drive, after 5 minutes the MFA was showing 44MPG!!! unreal… gave it a run on duals as well, pulled on my drive & had a reading of 38.1MPG! with the top down… really happy how it's progressed & the result, get it booked in for a tune next week & that should be the engine sorted for a long long time!!! Sounds how an old skool GTI should…
Cheers to everyone who helped & advised (also the Bentley & Haynes manuals lol)