550 Maranello fuel deliver interruption | FerrariChat

550 Maranello fuel deliver interruption

Discussion in 'Technical Q&A' started by Tom Mathews, Jul 2, 2020.

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  1. Tom Mathews

    Tom Mathews Rookie

    Apr 4, 2020
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    #1 Tom Mathews, Jul 2, 2020
    At start up engine runs fantastic, stop for fuel and restart engine and it runs on six cylinders, drive home on six cylinders, let car cool down, restart and then engine runs fine! New fuel pumps installed, but no change.
     
  2. Qavion

    Qavion F1 World Champ
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    #2 Qavion, Jul 2, 2020
    No Check Engine Light or Slow Down Light? Do you know which bank failed?

    What diagnostic work led to the replacement of the fuel pumps?
     
  3. tazandjan

    tazandjan Three Time F1 World Champ
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    #3 tazandjan, Jul 2, 2020
    Sounds more like an ignition problem than a fuel feed problem. Just to be sure, the fuel filters were changed, right? Those tend to clog up from deteriorating rubber holding the fuel pump in place.
     
  4. Qavion

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    #4 Qavion, Jul 2, 2020
    If temperature is a key factor, you have to look at what things are affected by temperature. Components such as relays and wiring get hot, engine management switches to normal closed-cycle which means different sensors are used, the exhaust gets hot, etc. I've even seen an earth connection change resistance with temperature.

    You have to be very methodical in your approach, otherwise you just end up throwing money at the car. Just because you saw something fix a problem in a 550 YouTube video, it doesn't mean that that is the only cause.

    Since you only have one post on the forum, we don't know the history of the car, your diagnostic abilities, general 550 knowledge, what diagnostic tools you have, etc. Why don't you pop over to the 456/550/575 forum and introduce yourself. Filling out your profile also helps us. We may be trying to offer you advice which is not applicable to your country or car.
     
  5. ferraridriver

    ferraridriver F1 Rookie

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    #5 ferraridriver, Jul 3, 2020
    Sounds like a bad fuel pump connection

    Feel at tail pipes for hot gas to determine which bank is not firing then check for fuel pressure on that bank.

    If both banks have fuel pressure then check round connectors at rear of intakes manifold (injector harness connection)
     
  6. Tom Mathews

    Tom Mathews Rookie

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    #6 Tom Mathews, Jul 3, 2020
    Thanks for questions/suggestions

    Fuel pumps replaced because of leaking fuel at fuel pump/tank connection. Upon inspection, both pumps replaced because of rubber bits from pumps in tank. Beginning to think as suggested that ignition is problem. Car at independent shop now and if there diagnostic can’t find fault then on to dealer.
     
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  7. ferraridriver

    ferraridriver F1 Rookie

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    #7 ferraridriver, Jul 3, 2020
    Also check both fuses and all 4 relays relating to fuel pumps
     
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  8. Qavion

    Qavion F1 World Champ
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    #8 Qavion, Jul 3, 2020
    Tom, here's a wiring diagram which includes the 550's fuel pump electrics:

    Ferrari_550_Engine_Service_&_HVAC Wiring Diagram

    It's a lot easier to make sense of than the original Ferrari diagram.

    Fuse/relay boxes tend to have problems over time. Sometimes it's a good idea to clean the contacts on the relays, otherwise you get additional resistance, heat buildup, melted relay panels and wiring. Because most things are duplicated on the 550, you can swap things out to see if the problem changes to a different engine bank.... relays, ignition coils, etc...

    Here are the ignition wiring diagrams (you'll have to use them in conjunction with the first diagram):

    Ferrari_550_Right_Bank(1~6)_Injection Wiring Diagram

    Ferrari_550_Left_Bank(7~12)_Injection Wiring Diagram

    Let us know how you go.
     

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