F355 F1 Issue. Starts It starts and immediately stalls

Coolant temp sensor can cause this if it fails. Given there are so many possibilities anything is just a guess. Here is where I would start after checking the coolant temp sensor, check spark plug covers for water ingress it can rust in there and could plugs, MAF sensor needing cleaned, throttle position sensor.

 

I assume you're referring to the pump relay and fuse. If it was your injector or pump relay/fuses, neither bank would run at all.

Not much to work with here. Can you tell if one bank is running? Do you have something to check the spark with? Those pen spark checkers are cheap, and will show if a coilpackis not firing (but won't really tell you if it's a good spark). Fuel pressure is difficult to check on the 5.2 because there is no schrader valve. Do you have a NOID light to see which injectors are firing?

After your recent AC compressor fix, idle control may be off, but you can't do a battery/reset idle relearn on the 5.2.

 

You should read the fault codes. As a quick try, unplug and plug back in the MAF connector a few times (to eliminate corroded contacts causing the issue you are having).

 

Will it run with the MAF plug disconnected?

You really need some simple diagnostic tools or a scanner as Miro suggested. e.g. To check that the crank sensor is ok, I pull the fuel pump relay and put a 12v 50mA miniature lamp across the socket contacts 85 & 86 and crank the engine. The ECU won’t energise the coil continuously with the engine being cranked if the crank sensor isn’t working properly. See the magenta line:

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Alternatively, just check for 12v power on the fuel pump fuse or O2 heat fuse when cranking the engine.

Is your IAC (idle air controller) buzzing when you turn on the ignition? It’s under the “Y” of your air intake. Have you tried partially depressing the accelerator pedal during cranking? Or maybe try disconnecting the IAC plug to see if your car idles.

 

North American F355 (5.2)’s should have an OBD port, unless the car was first delivered to Europe or elsewhere.
If the latter, you’d have to plug a “Fiat 3-pin to OBD2 adaptor” directly into your Motronic ECU. If you can’t find an OBD2 port under the dash near the steering wheel (I think), I would Google that Fiat adaptor. They can be tricky to set up as they also need 12volts to run. I wired one into a cigarette lighter power plug.

Whilst waiting for that to arrive in the mail, I would check to see if your local auto store has a pen type spark checker and/or a Bosch type 2 NOID light fuel injector checker.

 

The 5.2 will only prime the fuel pump once (for a few seconds). After that, no amount of key resets or even a battery reset will reset the priming logic. The engine has to be cranking (or possibly running?) before the logic is reset.

Sounds like you've found the problem (although I haven't looked at the 12 fault codes you posted earlier). I suppose the pump might not be getting full current due to high resistance in the wiring ... or your pump is U/S or blocked with rubber debris.

 

Also check the resistance between the pump ground wire and the chassis.

I can't remember a typical pump amperage value, but if you check the voltage across the fuse (with the relay shorted), this should tell you the current.

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You'll need special tables to compute the current from the voltage

You have to check the current this way because your typical multimeter can only handle 10 amps before the internal fuse blows. Of course, if you have a clamp meter, you can put it around the relay jumper wire.

 

https://caravanchronicles.com/wp-content/uploads/2018/10/fuse-voltage-drop-table.pdf

 

Looking at this thread, it may be best to go directly to Ferrari

https://www.ferrarichat.com/forum/threads/355-5-2-fuel-pump-bosch-part-number-69535.659756/

Not cheap.