Technical Fiat Punto Randomly stalls and won't start but disconnecting battery fixes it

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Technical Fiat Punto Randomly stalls and won't start but disconnecting battery fixes it

Nex

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Hello, my Fiat Punto mk2(188) 1.2 8v randomly stalls while driving or when idle. This can happen after 1 minute idle or after 20minutes of driving, no rules. Sometimes i drive it 150km without stalling, its completely random.
When stall happens, engine cranks like regulary but won't start. Fuel pump sometimes work, sometimes no. Diagnostics don't show any problem.(all codes from diagnostics are fixed).
The only way i can fix the problem is to disconnect negative cable from car battery, wait around 5-10 seconds, connect again and car will start without any problem untill random stall happens again.
Anyone with same problems and solutions? Help!
 

Kev_marea

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How did you discover the fix? Sorry I have no clue to help.

When you say fuel pump, before disconnecting battery, you mean you turn ignition on and you hear the fuel pump power up, but sometimes it does not power up and when it does power up the car does not start.? or have you disconnected the fuel line and seen the fuel flowing out?
 
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Nex

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How did you discover the fix? Sorry I have no clue to help.

When you say fuel pump, before disconnecting battery, you mean you turn ignition on and you hear the fuel pump power up, but sometimes it does not power up and when it does power up the car does not start.? or have you disconnected the fuel line and seen the fuel flowing out?

Before disconnecting battery, when the car stalls, i hear sometimes fuel pump, sometimes not at all. However, no matter if fuel pump turn on or no, car won't start. After disconnecting negative cable and put it back, i will always hear fuel pump and car will normally start like nothing happened before.
-I haven't disconnected fuel line nor seen any fuel flowing out.

I discovered fix totally random.

Do you have any car electrician to ask him about this problem? Maybe someone had a same situation.
 
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Nex

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But before doing that you should replace the fuel pump relay.
I checked, my car doesn't have fuel pump relay just F22 fuse. I don't know is that how it's supposted to work or is missing fuel pump relay.
Also i read it could be Ignition switch. My ignition coils are bad i noticed. But i don't know can it cause that type of car behavoir or no
 
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Nex

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UPDATE:

-I changed ignitions coils and ignition wires and car now acting totally different.

Yestrday i went for a drive, after sometime car stalled but this time was totally different. When stall happen and i press clutch rews will drop and engine will stop working but if i release clutch in gear it will continue to drive, before it would stall and even in gear won't start.
Then i stopped, tried to start it and it started well with a little bit throttle pedal. While i keep my foot on pedal car will work, when i release foot of the pedal car will stall immediately. Before i couldn't start car without reseting it, now with gas it's starting but still stalls. If i don't give him gas after stall, punto would just start and stall immediately.
 
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UPDATE:

-I changed ignitions coils and ignition wires and car now acting totally different.

Yestrday i went for a drive, after sometime car stalled but this time was totally different. When stall happen and i press clutch rews will drop and engine will stop working but if i release clutch in gear it will continue to drive, before it would stall and even in gear won't start.
Then i stopped, tried to start it and it started well with a little bit throttle pedal. While i keep my foot on pedal car will work, when i release foot of the pedal car will stall immediately. Before i couldn't start car without reseting it, now with gas it's starting but still stalls. If i don't give him gas after stall, punto would just start and stall immediately.

Your battery disconnection solution does not point directly to the crank sensor being the cause of this problem but if you get better performance from changing the coils and wiring it is possible you get an additional improvement? Crank sensors are known to stop working when they are hot and work again when cold.
 
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Nex

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I replaced crankshaft position sensor 3-4 months ago i think, problem was still there. That's first thing i replaced trying to solve this unusual problem. Also i replaced sparkplugs back then.
 

Mike1alike

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Aug 3, 2017
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The IACV (idle air control valve) on the throttle body could be causing your problem, among other possible causes (e.g. bad fuel pump). The IACV gave me terrible trouble and I've fixed the problem replacing it with a new IACV, here are the details, it looks like you have the exact model:
 
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