Runing problem found to be WUR - my story to fix it

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Runing problem found to be WUR - my story to fix it

Postby brooky » Sat Mar 05, 2016 5:21 pm

At last I have got my 2.8 running sweet again and just wanted to share the fix as it may help others. Car was running ok but taking several starts when hot so I had tried the usual accumulator, air valve not closing,fuel valve staying open, etc and all were found to be in order. I put new injectors in as I had 2 not seating properly but after changing them it would not idle, mix adjustment did nothing so decided to check all the fuel and HT system. Did all the usual basics like valve clearances, checked plate setting in intake venturi, checked mixer screw was working, new leads and plugs, worked better but no power and still not responding to mixture screw adjustments or idle screw.

So after much reading I was fixated on the WUR have read the pirinciples of how this operated. During cold start up it reduces pressure on the main fuel feed spool to allow this to put more fuel to injectors but when the WUR is warm either due to the engine heat or the in built warm up coil, the WUR is meant to close so that the main fuel feed is harder to lift thus leaning the mixture in normal running unless extra throttle is appled in which case a vacuum causes the WUR to come into play agqin to reduce pressure on the main fuel feed spool to richen the mixture at high demand. My car was starting ok but when warm it would not idle, would rev up ok in garage but no power when on road indicating it wanted more fuel despite the mixture being set ok at idle My analysis was that the WUR was not closing fully when warm thus allowing the main fuel spool to be in a richer position than it should be so when I wss setting the mixture at idle it was based on a spool setting that was based on main fuel infeed and an input from the WUR that meant my 2.8% CO at idle was not coming from the right setting on the mixture screw, it was basically a lean mixture setting plus a compensation from the WUR still being open allowing the main infeed spool to be in a richer positoon. This is also why my mixture screw had little effect as the WUR working on a hotengine was disguising the incorrect setting of the mixture screw and not allowing it to be as sensitive as it should be.

To check the WUR I allowed the engine to cool and disconnected the WUR return from the metering head so I could see if fuel was coming back from the WUR when hot as when the WUR is hot it should be closed with no fuel going through it to the return. As I could not run the engine to get the WUR to temp I connected it directly to the battery to let the internal heater warm it up as I knew this was ok electrically as I had done the resistance check on it. After 10 minutes I put the ignition to 'on' with the fuel relay changed for the rear screen heater relay so the pump ran constantly without needing to turn the engine over, no surprises fuel was coming out of the return hose showing the WUR was still open when warm. I removed and dismantled the WUR to find a lot of corrosion in the base plate section and powered it again to find the bimetallic strip was not moving when powered despite the heating element on it getting warm. I completely striiped the unit down following a previous thread found on the forum, cleaned everything up and dismantled the bi metallic strip, put some more curvature into the thinner of the 2 strips and reassembled. Before putting the base back on the unit I applied 12v again and the strip moved about 4 mm so I resealed and repeated the test on the car to find when warm the return line no longer had fuel coming through it so the WUR is now clising when warm

Run the car up to temp, idle screw now has an effect, mixture screw is sensitive as anything and actually makes a difference to the CO which is now 2.9% and 2.7% across both sides.

Just took her out and what a dream, responsive, no flat spot, starts first turn of key, bring on the summer.

This has being doing my head in, changing the injectors for new has allowed the problem that must have always been there to show itself, I can only assume the old leaking injectors were compensating the extra fuel being thrown at them by the WUR compensation even when hot.

My main advice to anyone else who is having similar nightmares trying to fix issues and feels like they are getting nowhere is to try to get a good understanding of the system you are having problems with and then test the components individually of that system to check their functioning correctly. On this problem it came down to the basics of saying that the engine is in good condition, valves are good, electrics good so all engine needs now is fuel and air in the right mix - what can effect that then check all the parts of that system individuallly and just keep telling yourself that if you have all the components working and set correctly then the car will run so which bloody one is not working :banghead:
Last edited by brooky on Sun Mar 06, 2016 8:14 am, edited 3 times in total.

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Re: Runing problem found to be WUR - my story to fix it

Postby sheff » Sat Mar 05, 2016 6:09 pm

Well done Mark.... Glad you've got it running good now. We'll have to meet up soon. Mothers day tomorrow, so might cause issues with the family if I have a Capri day :?

All the best
Neil

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Re: Runing problem found to be WUR - my story to fix it

Postby Andrew 2.8i » Sat Mar 05, 2016 6:17 pm

Hi Mark,
Good to hear that you've sorted out your running issues. I wouldn't have thought that the WUR could be responsible for such problems when the engine is up to temperature. It's certainly something for me to bear in mind for the future. I'm in the fortunate position that I managed to pick up a spare WUR recently. It appears to be in good working order, so it gives me the option to swap them over, should I suspect mine is not working properly.

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Re: Runing problem found to be WUR - my story to fix it

Postby brooky » Sat Mar 05, 2016 7:15 pm

Thats definitely my next move andrew to get a spare, that I know is fully working, Would love to get a spare of all the injection components as swapping out for something you know works is much easier.

The problem with the WUR problem is if the engine starts and goes straight to fast idle you assume the warm up system is working, problem is it also has to stop working when the engine is warm othterwise its like trying to set up a carb system with choke stuck on, will idle okay but in reality your mixture is lean

Just glad I now have chance to test run it before we get to the serious good weather, would hate to have been still trying to find a fault come spring.

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Re: Runing problem found to be WUR - my story to fix it

Postby brooky » Sat Mar 05, 2016 7:17 pm

No problem Neil, agree that mothers day takes priotiy although we could treat mums to a ride out in a capri, might try that one :python:

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Re: Runing problem found to be WUR - my story to fix it

Postby G4242 » Sat Mar 05, 2016 9:46 pm

Excellent post Mark. Sure we can all take something from this.

Glad your up and running again. :applaud:

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Re: Runing problem found to be WUR - my story to fix it

Postby nigecapri » Mon Mar 07, 2016 3:38 pm

G4242 wrote: Sure we can all take something from this


Yes ;)


















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Re: Runing problem found to be WUR - my story to fix it

Postby Pageyboy » Wed Apr 19, 2017 11:17 pm

Now this has me thinking ?? How did you hit wire the wur ? Having a nightmare with mine and I have been blaming the my metering unit. I have a spare wur that I bought 2nd hand but car wouldn't start with it on. Do you think my mixture could be out hence it not starting with it changed over ?

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Re: Runing problem found to be WUR - my story to fix it

Postby Arya2.0S » Thu Apr 20, 2017 1:20 am

Please excuse the silly question (2.0l 4-cylinder "peasant" here), but wtf is a "WUR"?! :lol:

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Re: Runing problem found to be WUR - my story to fix it

Postby Pageyboy » Thu Apr 20, 2017 10:17 am

Warm up regulator !! sits at the front of the 2.8 acts like a choke for fuel injection. I thought mine was working perfect as it start with a higher rev and calms down after a minute or 2 just like a choke but apparently it is possible mine doing that but not turning off hence flooding the engine but at same time running weak mixture. Got to love this 2.8 set up ha ha (not)

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Re: Runing problem found to be WUR - my story to fix it

Postby Peter-S » Thu Apr 20, 2017 11:20 pm

Pageyboy wrote:Warm up regulator !! sits at the front of the 2.8 acts like a choke for fuel injection. I thought mine was working perfect as it start with a higher rev and calms down after a minute or 2 just like a choke but apparently it is possible mine doing that but not turning off hence flooding the engine but at same time running weak mixture. Got to love this 2.8 set up ha ha (not)


The initial idle speed is governed by the air auxiliary valve which allows more air through when cold and gradually closes off as the engine warms up.

The WUR can be a pain. If you have one that causes the engine not to start I would suggest that the mesh gauzes under the larger bayonet fitting are blocked as this will stop the fuel flowing and give a constant weak mixture.
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Re: Runing problem found to be WUR - my story to fix it

Postby Not_Anumber » Fri Apr 21, 2017 9:48 am

Having nothing to compare it against apart from a 20 year old memory of driving my last one I've just assumed my 2.8 engine is doing what it should as it seems to run ok but this has made me want to check what i can to make sure the injection system is all working as efficiently as it should.

From your experience have you got any pointers on what should be checked and any parts you feel should be dismantled and cleaned on the system as preventive maintenance ?

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Re: Runing problem found to be WUR - my story to fix it

Postby Peter-S » Sun Apr 23, 2017 4:02 pm

Not_Anumber wrote:Having nothing to compare it against apart from a 20 year old memory of driving my last one I've just assumed my 2.8 engine is doing what it should as it seems to run ok but this has made me want to check what i can to make sure the injection system is all working as efficiently as it should.

From your experience have you got any pointers on what should be checked and any parts you feel should be dismantled and cleaned on the system as preventive maintenance ?


I'd have to say that if it is running Ok I would leave it alone!
If it starts first time, revs OK from the off with higher revs dropping down to normal idle speed as it warms up and the emissions are fine at MOT time then all is probably fine.
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Re: Runing problem found to be WUR - my story to fix it

Postby Andrew 2.8i » Sun Apr 23, 2017 4:07 pm

Peter-S wrote:I'd have to say that if it is running Ok I would leave it alone!


:agree: Wise words! Although I think that a sensible precaution would be to regularly change the fuel filter.

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Re: Runing problem found to be WUR - my story to fix it

Postby Not_Anumber » Mon Apr 24, 2017 9:37 am

Is that a gauze filter within the injection system on the cannister one ?

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Re: Runing problem found to be WUR - my story to fix it

Postby Peter-S » Mon Apr 24, 2017 9:40 am

Not_Anumber wrote:Is that a gauze filter within the injection system on the cannister one ?



The canister one on the inner wing
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