Citroen ZX XUD9 engine won’t start | Thought Draw

23 Aug 2014 | Author: | Comments Off on Citroen ZX XUD9 engine won’t start | Thought Draw
Citroen ZX


Citroen ZX XUD9 won#8217;t start

Posted: April, 2011 in Cars

I got in my ZX typed the code into the keypad, cranked and cranked, but no Panicked slightly, at this it was 18.30 and I was 60 miles from Gave it another go and voila up with the most almighty of blue smoke.

  The car then flawlessly at 70 mph all the way home.

Next day I to drive it and this time it wouldn#8217;t start.  Due to my flawless home only a day earlier, I it wasn#8217;t injector issues.  If it the failure would have me down on power and dropping of black diesel smoke.  Due to fine once started, it be the last two reasons for not starting below:

 The glow are not being powered #8211; start, runs fine going.)

 The stop is not lifting. (won#8217;t start, fine once going.)

Air in the (might start and cut out or idle/run

Low compression, ring or valve (driveability and fuel consumption suffer if you do get it started)

Don#8217;t their is no lift pump to fuel is brought to the high pump via the hand primer on top of the engine mount on cam belt the only failure is for it to allow air the sytem.

First things first, engines will very start from cold red hot glow plugs #8211; simply does not generate in cylinder temperature.  They are easy to check, all you need is:


An 8mm spanner / socket

A multimeter

1) you have a decent battery.  I set my up to read in the 20v range and dropped my probes onto the battery Expect to see well in excess of for a healthy battery.

  With the off mine reads 13.14v.

2) Now you to measure the resistance to ground for plug.  To get an accurate reading I removing the power supply to the top of each plug.  Look in the image below, I have the power from the left glow plug.

3) Set your up to read low resistance, I set mine up for 200 ohm or Now connect the meter#8217;s ground to a suitable ground, negative terminal is fine.  The positive go on the top where the power rail expect a resistance of less 1 ohm.  My number 1 glow measured a corrected 0.7 ohm.

  The correction is -0.1 ohm as this is the measured when I touch the two together.  If  the glow plug has it will read open giving the resistance of thin air very high!!)

4) Assuming all are in good shape, you MUST that they are being when you turn on the ignition.  Do not this step because it is likely that a sudden no condition is caused by a bad earth or relay box, pictured

5)  So if I think back to school a of formulas can be used to theorise voltage should be read the power rail feeding all 4 plugs.  Assume all plugs a corrected 0.7 ohms.

Rtot (1/0.7) x 4)

Rtot = 0.175

We can meaure the voltage across one this is essentially acting as a divider :

– Vin is the supply acting across the whole this is battery voltage = in this instance.

– is the equivalent of Rtop = 0.175

– Rbottom is the resistance earlier across one of our glow Now we want to measure Vout that glow plug.

= (0.7 / 0.175 + 0.7) x

Vout = 10.51 volts

we can apply kirchoffs 2nd law: sum of the emfs in any closed loop is to the sum of the potential drops in that

Applied below, where x = drop.

13.14 #8211; x = 4x

= 5x

x = 2.63

Citroen ZX

one potential drop is at 13.14 -2.63 = 10.51

In actual fact I measured a 9.43 volts across my plug when I turned on the on during glow plug period:

The crucial step, up the plugs and measure voltage on the rail

So how much heat are babies pumping out when get switched on?

V = IR

I = 9.43 / 0.7

I = 13.5A per giving a power of P = IV, P = 127 Watts.

I seem to have digressed.  you have power going to rail and after approx 20 you see the voltage across a charged plug drop back to listen to the relay box as it clicks If something is amiss, try bashing the box or simply unplug, clean up the and plug back in.

If you absolutely must get home, I spraying 1-2 seconds worth of start parrafin or perhaps try some WD-40 into the This has a low flash point and combust from cold glow plugs, allowing combustion to initiate.  Beware occurs rather uncontrolled, it nasty knocking- potentially big end bearings.

  It can also cause the to over rev as it burns uncontrollably, being said, use sparingly too little than too much.

If checks confirm glow to be working, it is likely that the to start is caused by the stop On my car it is used in conjunction with the When the immobiliser is satisfied you typed the correct code it a message to a unit hidden a tamper shield.  This upon receiving the message, 12volts across the solenoid and a plunger up.

  This plunger is to stop fuel from drawn from the fuel into the pump when Check out the suction cup on the bottom, the of the pump drawing fuel in, pulls the plunger on tighter, in the #8216;off#8217; position.  Here#8217;s it looks like when

The offending article

So with stopping fuel flow, my was not ever gonna start!  To get to it is not The stop solenoid is hidden a hardened steel shroud.

  There are 3 sheer bolts a nut and bolt at the bottom stopping any be#8217; thief from exactly what I needed to do remove the plunger and therefore the engine to start.

I borrowed the of a local handyman for the afternoon.  He got the off in a couple of hours using a chisel and centre punch to the sheer bolts.  And here it is

You can make out where the chisel in to those bloody awkward Don#8217;t be afraid to disconnect the pressure fuel lines and manifold to improve access for chisel to work the bolts #8216;slowly but surely#8217;.  I am told the awkard of the three is the one at the bottom in this image, directly the other two).

  He used a to get a visual on the bolt and hit it round a centre punch.

With the shield off, we pulled the solenoid out and watched to see if it popped in and out the ignition and code.  It did but I reckon was due to all the disturbance it had had.  I insisted we the pump with the plunger removed from the solenoid to see if the old would run.

We had to bleed the high pressure lines as they had been out to improve access.  This was by loosening one at a time, the unions the injector body and cranking the until fuel started out at the injector, repeat for all four.  Now I for a further 3 #8211; 4 secs my assistant held the throttle It fired and ran for the first time in a I quickly removed the key from the and of course it kept going.

  of doing this, I believe you the battery circuit from the whilst it is still generating this is not advised and can damage

I cannot switch the car off any more the key, I need to pull on the cut off under the bonnet or simply the engine in gear.  I could a new solenoid to operate off ignition but where#8217;s the fun in that?  Instead I tug on this rip cord when finished with the car. pictures)

Citroen ZX
Citroen ZX
Citroen ZX
Citroen ZX
Citroen ZX
Citroen ZX
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