V40 no start, has spark, has fuel...!!!

[Al115]

Thanks mate. I have had a meter on the battery both when static and when cranking and it looks pretty normal. I've also tried jumping the car from another when cranking just in case... makes no difference

MAF... I think I might have a spare somewhere... but it would have thrown a fault code I think.

Confused, me!

[Mrs_PA]

MAF... I think I might have a spare somewhere... but it would have thrown a fault code I think.

It doesn't always throw a fault. Just remove it. It won't run well without one, but if it fires up, you know where to look.

If everything else is OK, I would suspect a sensor or sensor connections somewhere.

[Johnny5]

hiya. How are u checking for a spark? Im my past experience if the spark doesnt look bright blue when tested out of the cylinder then it can dissapear totally when under compression! Also if u have a faulty engine temp sensor ur ecu could think that the engine is hot and therefore not inject enuf fuel! P.s are the plugs wet with unburnt fuel after cranking?

[Johnny5]

also try unplugging the temp sensor, the ecu should then revirt to a "base" value for eng temp. Alowing u to start the engine

[Al115]

hiya. How are u checking for a spark? Im my past experience if the spark doesnt look bright blue when tested out of the cylinder then it can dissapear totally when under compression! Also if u have a faulty engine temp sensor ur ecu could think that the engine is hot and therefore not inject enuf fuel! P.s are the plugs wet with unburnt fuel after cranking?

Going for the amateur method of laying the plug on the top of the engine and cranking

Sparks don't look super-strong it has to be said, but I can't believe that both coils have suddenly reached end-of-life... though I'd really like to borrow a couple to test

Plugs aren't wet with fuel after cranking.

[Al115]

also try unplugging the temp sensor, the ecu should then revirt to a "base" value for eng temp. Alowing u to start the engine

No start worth a try though, anything is at this point! Cheers.

[nellysv70]

if all else fails put a match to it lol i would say its the ecu but im no machanic it could also be your immob might be deactivating the light but not the system

[Al115]

It has crossed my mind... the "gallon and a match" approach...!

[Johnny5]

If the plugs are not wet with fuel (also smell the exhaust) then its not injecting enough fuel..... Did you say that you had pushed in the end of the shrader valve on the fuel rail? to check if theres fuel pressure? also just a thought thats outside the box.... Could the cambelt have jumped a tooth or 2? Maybe worth popping the cover off and checking the belt!
J5

[Johnny5]

if all else fails put a match to it lol i would say its the ecu but im no machanic it could also be your immob might be deactivating the light but not the system

Hey nelly.... Brighton here 2 m8y!

[Johnny5]

Hey nelly.... Brighton here 2 m8y!

Im sure ive seen ur (GAWJUS) motor near here..... If you hail from the eastern side of brighton then i defo have! And im sure i gave ya a blast of me pipework the last time i saw you, we will have to have a meetup, cos i think u live pretty close to me! lol

[Al115]

You need to check the 'Amp draw' on the fuel pump fuse with an amp clamp. Expect to see 12v and between 3-6 amps either on prime or crank. If it's less, then the fuel pump is open circuit or they have run out of fuel - (faulty gauge). If it's more then the fuel pump is seized.

Peaks at 8A when the ignition switch is turned to position 2, then a steady 6.5 to 6.8 while priming. Does this tell us anything useful?...

[Al115]

If the plugs are not wet with fuel (also smell the exhaust) then its not injecting enough fuel..... Did you say that you had pushed in the end of the shrader valve on the fuel rail? to check if theres fuel pressure? also just a thought thats outside the box.... Could the cambelt have jumped a tooth or 2? Maybe worth popping the cover off and checking the belt!
J5

Yep, I've prodded the Schrader valve and there's definitely a reasonable amount of fuel... I can't tell if it's 3 bar or not, but the easy-start should have ruled that out as a problem.

I even took the cambelt cover off to check for the worst - fortunately it looks fine!!!

[readview]

Hi Alistair,there are two problems that can cause this set of symptoms that we have come across,one is what we call"lost compression syndrome",basically the rings stick into the pistons for no good reason and this can occur anytime,it does not seem to matter whether the car is left five minutes or five days,there is no logical pattern.The giveaway is that the engine turns over quicker than normal and sounds like the belt has broken.(you could compression test to be 100%)The cure is a good quality engine flush and wind it over for ages until it starts.You will need a fully charged battery and possibly a booster pack as well as this can take some time.It is important not to touch the gas pedal during winding over.The car will slowly pick up on one cylinder,then two and so on.Dont touch the gas until it is running on all four and then only gently or you will be back to stage one.Change the oil and filter when it's had a good half hours running.We have had this on 850's,960's and the occasional S40.
The other possibility is a devious one and sounds stupid but please trust me it's for real,a duff starter motor.I know the car is cranking fine but we have had quite a few cars where the starter has gone faulty in such a way that under cranking it is drawing too much current and denies the injectors and sometimes the plugs enough juice to do the job.Most common giveaway is a small cough (attempt to fire) just as the key is released after cranking,this is because as the starter is denied juice the motor is still rotating and the proper signal gets through just as the engine stops turning.To prove this problem (or rule it out) tow the car and try to start it in gear.If it starts then replace the starter motor.
hope this helps,Adam.

[Al115]

Thanks VERY much Adam for the suggestions. Some really good ideas there!!!

I think the first scenario is unlikely as the car does not crank like it has a broken belt, but normally. I checked the compressions (cold engine, dry) and they were very low though:

Cylinder - Bar (now) - Bar (last time - Apr 2007)
1 - 8.8 - 14.5
2 - 10.5 - 14.8
3 - 12.5 - 14.5
4 - 9.0 - 14.9


which isn't a great sign I guess.

The starter possibility is another good one, however there is none of the "cough" or "nearly starting when stopping cranking" that you mention. It just stops absolutely dead when you release the key - "deader" than when it used to work, and you cranked it but not enough to start, if you know what I mean.

Still thinking on this one. Hope I haven't missed anything obvious!!!

[MrMopp]

Slipped timing belt and bent valves ?

If the problem was purely low compression then easy start would have got it going !

[Al115]

How could I check that? I checked the belt visually and couldn't see anything amiss...?

[LeeT5]

Hi again. Well this is causing some confusion isn't it?

Firstly m8, rule out ECU. If you have switching (injector pulse) then you have both 12v live and crank signal (rpm) from the crank sensor, via the ECU.

We know you have a spark and we know you got fuel. The amp draw reading you got on prime and crank (earlier post) is normal m8! So that rules out fuel pump.

One thing that does concern me...compression! 130psi is too low m8. I would expect to see 150psi minimum (180 - 240psi wet is normal).

As for the starter motor issue that someone else mentioned...never heard that one before in the 19 years i've been in the trade!

You can test the starter motor very simply without undoing anything m8.

Stick your amp clamp around the earth cable on the battery and crank her over. Once the initial inertia is overcome, the reading should stabilise at between 150 - 250 amps. This is normal for a petrol engine. If you get anything higher then you will need to replace the starter. Before you do this thou, make sure you 'volt drop' the starter circuit to rule out any high resistance ie poor earth connections.

So...you need to figure out the loss of compression before you go any further. Do yourself a favour and check the compression with a squirt of engine oil in each cylinder. This will simulate a lubricated cylinder as constant cranking with the injectors switching will just borewash you engine and cause very low compression. Pull the Fuel pump fuse so no fuel is injected m8, otherwise you will be back to square one. I will PM you my number so you can ring me, otherwise your gonna be here all week waiting for replies.

My guess is the car is simply flooded and has lost compression. If you have a spark, switching and fuel then the car should start and nothing but nothing will stop it. However...a weak spark will cause flood situation in a matter of seconds, as will a faulty coolant temperature sensor. Then couple that with the large amounts of fuel being injected on crank and you will quickly borewash the cylinders and loose compression and make the situation worse.

To overcome a borewash you will need to:

1. Remove fuel pump fuse to prevent further fuel injection.
2. Have a boost pack or fast charger to hand to charge and prevent vehicle battery discharging.
3. Remove plugs, clean and heat up on a heater.
4. Crank engine to expell excess fuel via spark plug ports.
4a. Continue cranking (10 seconds maximum - don't cook the starter) 20 second intervals until engine note audibly changes and sounds normal. This could take a few minutes.
5. Refit (warm or hot plugs) ensuring correct gaps.
6. Connect leads etc.
7. Refit fuel pump fuse and turn ign on (do not crank). Do this 3 times to prime fuel circuit.
8. Crank vehicle (do not touch throttle)

Vehicle should start, if not...stop cranking. Remove fuel pump fuse and crank again. regain compression and replace fuse. Crank again. Hopefully she will start.

[Al115]

You're a legend mate. Thanks so much for typing all that in!!!

I will try tomorrow.

[daveforber]

I just had a thought (that's probably as irrelevant as my first, but no matter, it won't hurt). I had this once on a Citroen diesel (it was before I saw the light). It cranked and cranked and just wouldn't start. Turned out to be the head gasket. Obviously there were earlier symptoms like running hot, but I didn't realise what that was at the time.

The AA chap who popped over reckoned he could test it by removing the radiator cap and cranking. It spat water high into the air (can't remember the reasoning - probably something to do with pistons and water).

Worth a look?