help with 1.8 engine no spark

[barryandnaya]

We are new to this forum and have infact got a fiat punto 1.8 HGT, which we are told is the same as an Alfa engine.
We have not been able solve a mystery problem with this car, no spark.

It had work done previously, including new timing belt, inlet valves and a new headset (it had a snapped belt). Afterwards the strangest thing was it it started fine (after fitting a different battery). We took it for a little drive, perfect. Parked up,went back 15 mins later, WOULDNT START! upon checking it has no spark, suddenly. We have replaced the crank shaft sensor and it has done nothing, replaced the spark plugs, nothing different occuring. We dont want to take it to fiat as there is no light on to our knowledge and so it would be a waste of money which is scarce just now.

Another problem this car had is that something is draining the battery, it has actually physically killed 2 batteries beyond repair, again we cant find the fault.
At this moment in time we feel like taking a large axe to this car, however we have spent alot of money and time fixing it,for it to lose its spark suddenly for no apparant reason.
We have asked on the fiat forum with no joy, it seems to be a mystery, we are hoping someone on here may shed some light on this mysterious no spark problem

[wayne-dear]

Sorry i can be of no help, i am sure that soon someone that can help will be along .
Welcome to AO..

[barryandnaya]

Thank you for the welcome. Yes i do hope someone can help. Its just going to sit there until we do as we are at a dead end

[rgwm]

Although there may be similarities I don't think the HGT engine is the same as an Alfa one, but as I'm an Alfa specialist not a Fiat one I can't be sure. On an Alfa the problem would probably be down to a bad wiring connection to a relay near the battery....but not sure if this is the case on the Punto.

The electrics draining is possibly related, but really can only be checked by someone with a multi-meter to identify the current drain, possibly by pulling fuses one by one to check which circuit is causing the issue. It could be a faulty diode in the alternator, of course - if you can get to it you could check whether it gets hot when not switched on......

If you are anywhere near Richmond there is an Alfa-friendly garage there who would possibly be able to advise without costing the earth....

[WhizzMan]

Altho the mechanics of the engine are almost the same, except for 4 spark plugs you are "missing", the electronics are different.

I would advise you to check all wiring, plugs (also underneath) on the ECU/Engine loom. No spark usually means no power to the ECU and/or the code box, or a faulty (wired) crank sensor. As rgwm mentioned, on alfa's it's often the relay cluster that would be located on the battery tray. On the Punto the wiring may be different. I've not done enough of them to remember the exact location of the wiring and the ones I've done were 8V, so probably totally different. However, since all cars still function roughly the same, these are the points I would check if I were you.

If possible, try and find someone with "fiatecuscan" or "unidiag" and the appropriate USB cable for that. They should be able to read out at least part of the ECU (if it is getting power at all) and see if it's functioning.

Is your fuel pump "primed" when you turn the ignition to "run" but don't start? You should hear it running for a few seconds and then shut off. If not, this is a strong pointer to your ECU not getting power.

[pull]

some points worth following made here alfa155.org :: View topic - can you help this guy cristian?

(posted on a forum I use full of super-clever folk)

[barryandnaya]

Thank you very much for the replys.

I will tripple check all wires, and im not sure which relay it could actually be?
To answer a few questions: We have been on the fiat forum but noone seems to know what it could be. We have spoken to a garage (fiat) and they have no idea either as we have tried all the normal stuff. We have searched and read alot of conversations on the net about this type of problem, tried all we have seen. Spent all our money for the head, timing belt, spark plugs, timing tools, valves, batteries, crankshaft, which is why we could afford to replace them but now we have spent all our money? Which is why we cant take it to a garage just now. There has to be a line drawn at some point to howmuch is spent on it, its a fiat punto at the end of the day! Not worth too much these days are they - hence the posting on here - quite simply a last resort to be honest as its a fiat not an Alfa, however someone suggested we try this forum as the engines are practically the same.

Will try all the ideas suggested here

Thanks for the effort of those who replied - i will update asap

ps how do you test relays??

Oh and it is a 1.8 16v (these seemed to be a bit of confusion about that) :-)

[Ralf S.]

I presume the engine cranks over but just doesn't fire?

Is there a spark at the plugs? Connect one HT lead to a spare plug and rest that on the engine, so it's earthed. Can you see it sparking when you turn the engine over?

Are the injectores getting current? Remove one of the leads to an injector and connect it to a meter or a bulb instead. Use a glass-bottom bulb, the type with the metal tangs folded back against the glass bulb-base.

If you have no sparks, no injection or neither, that will point you in the right direction.

"Neither" would suggest the TDC sensor or ECU, as discussed here.

"No sparks" or "No injection" could suggest a relay.

Sparks AND injection (but no joy) would suggest something connected with the fuel pump. Check at the fuel pump end that when you turn the ignition on, the pump gets a "flash" of priming current.. and that the current pulses to it as the engine turns over. (Has the fuel-shut-off doodah been tripped?)

If the pump is getting juice, then is there fuel at the injector rail.. (if not = pump problem).

It's probably something not toooo major since the beast was running okay until you switched it off... so it's just a case of being methodical to find out which bit isn't working..

Ralf S.

[barryandnaya]

Hi, thanks for the reply. We have NO spark, but we DO have fuel!

So this is suggesting we have a relay problem? We cannot find any info on what relay works what?

Like you say its something simple, surely, as it was running perfectly fine, and didnt die we turned it off and its never started since!

Do you know what would cause no spark? But still have fuel?? I phoned the ECU docter but he doesnt even think its worth testing the ECU he said it didnt sound like an ECU fault.

The only thing i can think to replce is the CAMSHAFT Sensor im not sure if this could cause no spark? Obviously replaced the crankshaft sensor but no joy.
I dont have a wiring diagram for this car either which makes it motre difficult. The cm sensor will be about £90 so its alot for a guess that may do nothing!

Does anyone know what would cause no spark but still have fuel????

[rgwm]

On an Alfa the camshaft sensor failing won't stop the engine running. One thought - when you replaced the crank sensor, did you check whether the sealing ring came out with the old sensor? If not, and the new sensor had a sealing ring , then the sensor won't be close enough to pick up the signal....and the engine won't run. Again - this info based on Alfa experience.

[barryandnaya]

Hi, yes it came out and yes the new one has one! So frustrating.

Could fiat actually diagnose this car if the engine light isnt on?

trying to get a wiring diagram to see about relays.

[stratos]

Originally Posted by barryandnaya

Hi, thanks for the reply. We have NO spark, but we DO have fuel!

Does anyone know what would cause no spark but still have fuel????

How long do you have fuel?
I mean - the crankshaft sensor pulses are necessary to make the fuel pump work. Otherwise the fuel pump could be running after an accident, which could be very unfortunate.
Correct me if I am wrong, but I think that the fuel pump stops after e few seconds if there are no spark pulses.
Can you hear the fuel pump work?

[Ralf S.]

Yes, if the TDC sensor isn't working, then the injectors wouldn't be getting power either.

I'm not sure if the fuel pump works regardless of the TDC pulses to the injectors.. though I can't think how else the fuel pump knows when to pump, except by receiving a signal from the TDC sensor..

But you can eliminate the TDC sensor by connecting one of the injector leads to a meter or bulb and see if the injector itself is receiving power. If the injectors are working (regardless of the fuel pump/delivery situation) then the TDC sensor is working.

If there's injector power but no sparks, then start from the coils and work backwards. If you can find a tame mobile auto-electrician he'll be able to find where the break is.. but it's a good bet it'll be around one of the relays in the engine bay or their wiring.. the joints can get corroded a bit and break off.

If you don't know which relay to investigate, check them all out. Get a little mirror and have a look at where the wires go into the connector block.. and also that the connector block and the relay spades are clean and in good contact. If you have 2 identical relays, it's worth just swapping them over to see if it makes a difference.


Ralf S.

[barryandnaya]

Just wanted to update - It was the cam sensor! So there you have it - If you have No Spark and you have replaced The crank sensor and spark plugs try the cam sensor or better known as camshaft sensor! Hope this helps with someone elses nightmare

[barryandnaya]

The car is fixed, please read my previous post but thanks anyway the problem is long gone