Ford Sierra 2.0 EFi DOHC Fuel pressure regulator

[Morgan84]

I have a 1992 Sierra Ghia Auto,and lately,it has developed a glitch where it will suddenly start surging,and run rough,and if stopped at traffic lights will sometimes die.I had thought the first time it done it as it was a very wet day,and that I had some damp under the bonnet,but its been doing it today,so its not a damp issue.Usually,it will be noticable in a 30 limit,but if you kick it down,it goes off like a rocket,and runs fine for a short while.I have checked compressions,and plugs - replaced just in case,checked for air leaks.The vehicle seems to want to run quite lean,but when it plays up,it runs rich,and from the fuel pressure regulator,it sounds like its buzzing ( like a electrical arc sound ).The plugs did come out looking quite sooty,so I'm pretty certain my culprit is the regulator ( Weber unit ),which is causing over fueling.I'm almost 100% certain the idle control unit is working perfectly fine,as she ticks over at a steady 800 rpm,until the car runs lumpy,and then dies

My question is has anyone on here had this problem before with either a Sierra,or Granada ?,and if it is a common fault,I shall be asking Mr Ford for a shiney new one.As these cars are getting older,and are before the plugit in and see days,we need to rely on past experience and wisdom as most Ford technicians will have forgotten what a Sierra was !

[Mr_Bo11ox]

I would diagnose this by buying a cheap fuel pressure gauge off the bay, less than a tenner delivered. thats how i got to the bottom of the starting problems on my CROMA

[red5]

Check the ISCV before - the usual, wash it out with carb cleaner. Maybe soak for a short while with brake fluid. Check the end cap for a 'X' stamped in it. Those are the later valves. The early ones were a bit prone to clogging.

[Bren]

Had a couple of V6 granadas with similar symptoms - both times it was the throttle potentiometer.

 

Try disconnecting it - the car will run on a limited operation strategy. Things may improve.

[Morgan84]

I shall have a good poke and clean round any connectors and sensors that I can find,and see if anything looks obvious - I'm sure its nothing too major,but its the same age old problem - the older they get,the harder it is to get parts as easily - most were heading towards the breakers 10 years ago !

[mk2_craig]

I've got a spot of hesitation on my DOHC Sierra when accelerating from idle, I've learnt to deal with it by feathering the throttle pedal and pretending it's ok. Other half can't get to grips with that though I asked someone I know in the trade who likes to think of himself a Ford specialist and he muttered something about head gaskets, which neither helped nor made sense.

[Morgan84]

They 'can' have headgasket failure,but mines on its original - the only thing that was done 9 years ago was new timing chain and guides which do give trouble with age.Maybe try a new fuel filter with yours,and check what the CO readings are - the adjustment is a little black box with a flathead screw adjuster on the offside inner wing,near the suspension top mount.

[mk2_craig]

Thanks for the advice! The HG on my car does have a small oil weep at the front of the engine, at 49k miles I don't doubt its the original one so probably worth biting the bullet and replacing it anyway. Though ten years ago I'd have used that as an excuse to lob a 24 valve V6 in.

[Morgan84]

K seal is a good 'time buyer',but slight oil seepage isn't really such a problem,until it starts leaving drops where its parked - most things get incontinant with age !!

[red5]

Re the hesistation just off idle - can be early sign of head corroding due to lack of coolant/incorrect changes in a lot of I4 DOHCS. Eats away at a water passage until gasket fails/misfire on idle that goes just off idle.

[Morgan84]

So many sensors to look at - MAP sensor,Coolant temp,Air temp,Fuel Temp,Pressure regulator,Throttle potentiometer ..... I wish whatever is playing up would just die completely so I can find it,and change the damned thing.Still,in 10 years,never given me any trouble,so I guess its about time I got some !

[mk2_craig]

Maybe the fuel pump itself?

[Morgan84]

Its in the tank on mine - I hope to god its not the pump !! Please be a nice under bonnet sensor * prays *

 

Well,I hope to crack it soon,as I love that old car,and its such a pleasure to drive,plus has a really good body

[Morgan84]

The outcome of this was ( not misbehaved in the last few short runs ) a replacement ECU coolant sensor,located behind the alternator below the temperature guage sender unit.This seems to have stopped the cars intermittant overfuelling;I think the sensor was making the car think it was cold,and making the cold start device work,and flood the engine.

[mk2_craig]

Apologies for resuscitating this thread with a different though possibly not unrelated problem. Just acquired a 2.0i twin cam Sierra, manual, won't start. Died just after a recent half tank of fuel went in. I am assured that it has not been misfuelled with diesel, that garage says nobody else has complained about dodgy unleaded, and that car ran 100% until conking out. Fuel is getting through to combustion chamber, spark at plugs, swapped coil with known good one and no difference. It isn't even coughing or trying to fire.

 

1. Any ideas?

2. How can I tell the fuel is definitely petrol?

 

Thanks in advance

[Lufthansa-Terminal]

How can I tell the fuel is definitely petrol?

 

Syphon a bit out as the smell may give it away. Plus a match will ignite petrol but not diesel.

[The Reverend Bluejeans]

A mate of mine in Sheffield is breaking a 2.0i DOHC Sierra Ghia..............

[Morgan84]

You can syphon a Sierra from the fuel filler with a long tube quite easily,and then have a look/smell at what comes out.How was the car running before it died,was it a sudden stop,or a progressive shutdown ? I know they have a ECU and disconnecting the battery and leaving it overnight might 'reset' it back into life.Another thing to check for is a compression test,as these are chain driven engines,and the chain guides can break,and let the chain jump,so its worth checking its not a mechanical failure as opposed to a damned electrical gremlin.

[mk2_craig]

Thanks for the suggestions so far, I will need to swap in a decent battery anyway so that might help, only other things I thought of are blocked air intake/filter and dodgy fuel cut-off switch, but I'm starting to clutch at straws. To be honest I bought it to salvage a few parts and then dispose of so I'm not too worried whether it runs or not, but it's sitting in the work car park and I guess shouldn't become a long-term resident if I can help it! Photo on my Sierra thread, anybody want a particular part (or the whole non-running thing), just shout...

[Morgan84]

You can hear the fuel pump operate with the ignition on,which I believe on these models is inside the fuel tank;another thing to try is see if the fuel filter has collected some shite,and is restricted.From memory thats underneath near the fuel tank,and is a large metal inline unit ( about the size of a oil filter ),with union connections,so will be a WD40 and pair of decents spanners job