Technical Help my Fiat 500 1.2 8V will not start!

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Technical Help my Fiat 500 1.2 8V will not start!

Have any work been done to the starter motor recently?
When you put the ignition on, if you press the accelerator a little bit, is the engine still not starting?
 
Have any work been done to the starter motor recently?
When you put the ignition on, if you press the accelerator a little bit, is the engine still not starting?
No I suspect on a faulty sensor. Crankshaft position, coolant temperature, MAP, throttle position sensor or the ECU itself.
 
Its very odd if the car has fuel and a spark it will run or try. I regert to say you need a diagnosis done. We have a firm Gendan.co.uk who sell software and leads for reasonable prices that you plug in the car to a laptop and can then see what is going on in all the engine systems. I can only day that I bought this and its paid for its self 10 time over over the 3 years since purchase. You can see injector voltage and pressure adn check coils and sparks and engine timing. It gives hints as to what to do if something is not running or is off spec. My other thought is whether th in tank fuel pump is working right. Low pressure could mean bad or no fuel injection. When you turn the ignition on you hear the pump buzzing. I dont know where the fuel filter is but if it has got blocked it could rarely acuse this sort of problem. When was the cam belt last done? If this has jumped you could have a staeting issue aand if its jumped a bit it needs sorting as it could take the enine out completley if if jumps again.
I'm all for trying the simple things first. It's reported that fuel and sparks are present but we don't know if the injectors are actually delivering fuel to the inlet ports. This is difficult to check but If sparks are being delivered it's likely that they are arriving at the right time because it's the crank sensor which determines this and if the crank sensor was the problem we'd likely be getting no, or intermittent, sparks. So, myself, I'd be spraying some Ezi start into the throttle body whilst cranking the engine. If it's a fueling problem then you'd expect the engine to run as long as you kept spraying. if it's a spark problem then spraying ezi start will make no difference.

At least this should narrow down whether the problem is fuel or spark related?

I think you are referring to Multiecuscan above? and I can endorse that Gendan are good and helpful people to consult with and buy from with excellent after sales backup. I also bought from them, I think about 5 years ago now? and I have regular and very useful contact with their Grant via Email where we discuss interesting topics. I completely agree with you when you say the MES has paid for itself over and over. In fact I think it probably paid for itself the first time I used it when we diagnosed an ABS problem on my boy's Punto - goodness knows what the dealer would have charged to sort that out!
 
I'm all for trying the simple things first. It's reported that fuel and sparks are present but we don't know if the injectors are actually delivering fuel to the inlet ports. This is difficult to check but If sparks are being delivered it's likely that they are arriving at the right time because it's the crank sensor which determines this and if the crank sensor was the problem we'd likely be getting no, or intermittent, sparks. So, myself, I'd be spraying some Ezi start into the throttle body whilst cranking the engine. If it's a fueling problem then you'd expect the engine to run as long as you kept spraying. if it's a spark problem then spraying ezi start will make no difference.

At least this should narrow down whether the problem is fuel or spark related?

I think you are referring to Multiecuscan above? and I can endorse that Gendan are good and helpful people to consult with and buy from with excellent after sales backup. I also bought from them, I think about 5 years ago now? and I have regular and very useful contact with their Grant via Email where we discuss interesting topics. I completely agree with you when you say the MES has paid for itself over and over. In fact I think it probably paid for itself the first time I used it when we diagnosed an ABS problem on my boy's Punto - goodness knows what the dealer would have charged to sort that out!
I sprayed deodorant. This should also burn. Engine doesn't respond to it. So still ignition timing tip?
No spark for the first few rotations. Shouldn't the spark come right away?
 
I sprayed deodorant. This should also burn. Engine doesn't respond to it. So still ignition timing tip?
No spark for the first few rotations. Shouldn't the spark come right aw
I notice that our Panda and my boy's Punto both go over compression a few times before firing up so maybe the ECU needs a couple of revs to sort itself out before initiating sparking? It's pretty standard practice for fuel delivery to be delayed until the ECU is sure cranking is taking place. I've never tried spraying deodorant into an engine's intake. Maybe it's propane/butane powered - many aerosols are - so maybe it will act as a fuel but I just don't know. If you're getting a spark, even if the timing is wrong for some reason, I'd expect you to be getting a "kick" from the engine or maybe a backfire? Of course keep your face away from the intake if you're doing any of this as a backfire could give you a nasty burn.

As so often today, running a check for stored fault codes could save you a lot of time and bother chasing false clues.
 
I notice that our Panda and my boy's Punto both go over compression a few times before firing up so maybe the ECU needs a couple of revs to sort itself out before initiating sparking? It's pretty standard practice for fuel delivery to be delayed until the ECU is sure cranking is taking place. I've never tried spraying deodorant into an engine's intake. Maybe it's propane/butane powered - many aerosols are - so maybe it will act as a fuel but I just don't know. If you're getting a spark, even if the timing is wrong for some reason, I'd expect you to be getting a "kick" from the engine or maybe a backfire? Of course keep your face away from the intake if you're doing any of this as a backfire could give you a nasty burn.

As so often today, running a check for stored fault codes could save you a lot of time and bother chasing false clues.
Oke then maybe thats normal. Yes fault codes are not there and also no misfire or pops/bangs.
 
I'd agree with the posts above re: earth cable
Does the car crank over at normal speed?

even after putting in a replacement cable - i still had issues, for some reason the earth strap needs to use the same points on the body (under the battery tray) to the gearbox (under the selector) a cable is about £8 and needs to be about 275mm long with 8mm holes (you can pick one up at any motor factors - doesnt have to be a specialist dealer part) , not a bad job to do and can be done in around 20 mins.
 
Have a look through this post which I started with my issues https://www.fiatforum.com/threads/bad-earth-poor-starting.489491/ and see if it sounds similar, I honestly went through almost everything, crank & cam sensors, wiring harness, replaced ECU, BCM & Ignition barrel, fuel rail etc. and ended up back where i started with earth - threw some very strange fault codes along the way too that weren't real.
 
You still didn't mention if petrol gets inside the engine. An easy way to check, without getting a spark plug or an injector out, is to disconnect the cable from one injector, connect a multimeter to it and measure the tension on the line while you crank the engine. If there's no tension it means that injectors doesn't open, so no petrol goes inside the engine.
 
You still didn't mention if petrol gets inside the engine. An easy way to check, without getting a spark plug or an injector out, is to disconnect the cable from one injector, connect a multimeter to it and measure the tension on the line while you crank the engine. If there's no tension it means that injectors doesn't open, so no petrol goes inside the engine.
Thanks for this information. I gonna check it and report back.
 
I'd agree with the posts above re: earth cable
Does the car crank over at normal speed?

even after putting in a replacement cable - i still had issues, for some reason the earth strap needs to use the same points on the body (under the battery tray) to the gearbox (under the selector) a cable is about £8 and needs to be about 275mm long with 8mm holes (you can pick one up at any motor factors - doesnt have to be a specialist dealer part) , not a bad job to do and can be done in around 20 mins.
Thank you. I am going to connect a jumper cable between battery and gearbox.
 
If it's sparking and there's fuel in the rail, then it can't not start, unless the fuel is off, or the mixture is too weak, or the car has become flooded.

If your petrol smells of nail varnish then it's a bit "off". Get some fresh fuel in there (use the super unleaded variety) and just top up what's already in there with as much new fuel as will fit (at least one 5ltr can will help).

You don't need to dismantle the car or check whether anything has slipped. Disconnect the battery lead and charge the battery up again. That will give it a boost and allow the ECU brains to re-set/re-check the sensor inputs it's using.

Meanwhile, remove the plugs and check whether they're wet or appear sooty. Clean them up regardless, and leave them out for a while so the cylinder can evaporate any pools of fuel (squirt some electrical contact cleaner down the plug holes to help the benzina evaporate.

Replace the clean plugs, refit the leads (give them a squirt of WD40 for good measure) and then reconnect the battery.

It should now just start. Don't touch the throttle.. just put it in neutral, and turn the key.. letting the electronics work out the mixture/throttle side of things. If you prod the gas, you'll flood it.


Ralf S.
 
I just read a really long thread here - but lost it I think its a link on one of the posts herein -on the earth strap. Its cheap its easily available, its easy to do ... just change it!!! Im going to change both our older cars this week a a precaution after reading the horror story of expenses in that post. Im also going to put a spare strap in stock. I find it hard to believe this can cause so many issues and heatache its almost unbelievable that something so basic can cause this issue.
 
You can test whether the injectors are working with a glass bottomed bulb, if you have one lying around but no multi-meter.

The metal prongs/tabs which are normally folded over one each side of the base, are just the right size to fit into an injector lead, once you have unfolded them. If the bulb flashes as you're cranking then the injectors are doing their thing (although you need to make sure there is actually fuel in the fuel rail, otherwise the injectors are squirting fresh air).

Have you also checked the dibber dobber that shuts off fuel in the event of an accident? It might just have tripped (although usually it takes quite a heavy jolt).


Ralf S.
 
You can test whether the injectors are working with a glass bottomed bulb, if you have one lying around but no multi-meter.

The metal prongs/tabs which are normally folded over one each side of the base, are just the right size to fit into an injector lead, once you have unfolded them. If the bulb flashes as you're cranking then the injectors are doing their thing (although you need to make sure there is actually fuel in the fuel rail, otherwise the injectors are squirting fresh air).

Have you also checked the dibber dobber that shuts off fuel in the event of an accident? It might just have tripped (although usually it takes quite a heavy jolt).


Ralf S.
Fuel cut off is electric on these and not a button like older cars it also says fuel cutoff active on the dashboard
 
I pulled an extra ground today with no success. Have looked at the original cable. No corrosion.

Turned out spark plug. Spark plug is dry.

Tested the injector. It is getting 10 volts.

The 500 does not have an accident switch. I did the manual with the blinker 3x left and right.

I measured and read live data today with the Torque app.

No error codes.

It indicates the throttle is fully open. While it is closed.
I think the throttle position sensor is responsible for this. Which causes the ecu to get false readings.

I tested the same thing on 2 other cars. There on ignition 15% is open and when I give full throttle 85% as with the Fiat 500 is constant.

What do you guys think about the throttle position?

New sensor I definitely need to calibrate.
 
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Injectors are normally switched to ground by the ECU, so having voltage on them doesn't mean they are working.
 
Injectors are normally switched to ground by the ECU, so having voltage on them doesn't mean they are working.
Thank you. How i need to check it? Nobody has info about the TPS signal?
I have the throttle body with integrated sensor.
 
is this a twinair version? Multiair (and I believe Twinair) are known to leak oil inside the unit (which drains into the engine, so no worries) if those engines are left unused for months. One month is not very long, but it might still need a prolonged starting effort (the oil pump will push oil into the Twinair unit to fill it up again). With insufficient oil level inside the unit, the engine will not start when turning the key shortly. It might take 20 s or more (especially if the car had not been used for several months). This has nothing to do with the oil level of the engine itself.

Extremely cold temperatures could also have an impact, my Punto was new at the time but it refused to start with outside temperatures of minus 18 degrees Celsius. Had to wait a week for temperatures to go up to minus eight. The car started without problems.
 
Thank you. How i need to check it? Nobody has info about the TPS signal?
I have the throttle body with integrated sensor.
Usual wasy would be to check the other side is pulsed, that needs some kind of oscilloscope, or you can use a meter if you know what to look for. Or a bit more extreme, pull the fuel rail and injectors to see if fuel is coming out.
 
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