456 GTA 1997 Wont start - need fuel system expert

Discussion in '456/550/575' started by spiderscott, Jan 13, 2018 at 11:05 AM.

  1. spiderscott

    spiderscott Formula Junior
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    Feb 24, 2004
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    Hi Guys

    New to the 456 & V12 side, need some help with my 456 GTA, its a 97 US car and won't fire up. I purchased the car like this been told it was parked up over winter and when bought out again had this issue.

    - Engine turns over fine and strong, Ive checked plugs and have spark.
    - Plugs look and smell dry - no fuel
    - checked fuses on board and all look ok.
    - checked pump wiring from behind luggage compartment panel - all ok.

    Questions-
    1. Should I heard either of the fuel pumps run when ignition key is turn on or door opened ?
    2. Is there a safety cut out switch anywhere like the 360 in the foot well ?
    3. How can I test the pumps and fuel getting to engine ?
    4. Is there something I could check at the fuel rails ?


    Any help would be greatly appreciated.
     
  2. rviani

    rviani Rookie

    Jun 22, 2005
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    The fuel pumps do not run when the ignition is first switched on, the engine needs to be cranked before the FI system calls for them to run. There is a Schrader valve at the front of the fuel rail which is used to check for fuel pressure when starting / running - should be about 49 psig. If no pressure check for a blown fuse and/or remove the fuel pump relay and use a jumper to run the pump.

    All based on my 95 456gt with Motronic 2.7 assume yours with 5.2 is the same.
     
  3. tazandjan

    tazandjan Two Time F1 World Champ
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    Not sure if the 456 GTA will turn over or not if the immobilizer is armed. 550s will not turn over, but 575Ms will, but will not start. Anybody know?
     
  4. henryr

    henryr F1 World Champ
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    what is it doing ? you turn the key and "nothing" or it turns over with the starter motor but doesnt fire up ?

    my 456 will not turn over with the alarm activated
     
  5. spiderscott

    spiderscott Formula Junior
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    Yes guys it turns over no problem, just will not fire up. Again when it turns over, I’ve checked and I’m getting spark to the plugs
     
  6. asgor

    asgor Karting

    Sep 8, 2016
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    Virginia, USA
    Scott, if you are looking for the Internet-variety armchair expert, then this is the place (hey, there's only so much one can guess based on your description). If, however, you want to pursue this issue, uncover additional symptoms and resolve it using a physical facility with diagnostic instruments and evidence-based knowledge and acumen then go no farther than your local trusted Ferrari technician - independent or otherwise.

    As one of those armchair mechanics myself here's my minuscule nugget of wisdom: did you try pulling codes with an OBDII reader (Motronic 5.2 is OBDII compliant - at least on US models)?
     
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  8. ferraridriver

    ferraridriver F1 Rookie
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    You can "hot wire"/jump the fuel pumps. There's no easy access in the trunk to a 12VDC source so I just go from the battery directly. You can check fuel delivery at the schrader valve on the fuel rail but be careful about fuel spillage doing this
     
  9. Cribbj

    Cribbj Formula 3
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    There should be an inertial switch on your 456 similar to the ones we have on our 550's. In our cars it's located outboard of the battery in the fender well. Check that out and see if it's tripped. They sometimes get moisture in them and the contacts get corroded.
     
  10. spiderscott

    spiderscott Formula Junior
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    Cheers, Ive been a long standing member on here for many years, just new to the 456 V12 circles :D. Been in the V* gang for 18 years and love FCHAT, have always written up anything to help others along the line and still get positive feedback on self fixes such as the 360 spider roof issues.
    Closest Ive got to V12 Ferrari's is a couple of Testarossa's ive owned with Flat 12's. Currently I'm over in the TR tread forum doing a much fun resurrection of a Testarossa Spider 'Rat Look Style' .... The Ratarossa:
    the-ratarossa-the-testarossa-spider-rebuild-project.499875

    Anyway Im learning fast about these 456's and love to do as much as possible myself never afraid to have a go and get my hands dirty.
     
  11. spiderscott

    spiderscott Formula Junior
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    So did a little more digging and research.

    Regarding the Inertial switch, this is proving to be illusive on the 456. Reading the owners manual this morning there seems to be a protection system for anti-roll on the right side of the fuel tank housing, but this unlike the 360's does not look like a switch. I will dig around in the car later and see it with my own eyes.
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  12. spiderscott

    spiderscott Formula Junior
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    Is this just a case of running a positive and negative wire to the two terminals on the fuel pump ? Ive a spare battery so this would be an easy solution to test
     
  13. spiderscott

    spiderscott Formula Junior
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    If I remove the fuel pump relays - any idea which pins I would need to put the jumper across on ?
     
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  15. spiderscott

    spiderscott Formula Junior
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    Research tells me its not uncommon for the rubber housing surrounding the 456 fuel pumps to disintegrate over time. I plan to get a tool and remove the pumps to inspect this. Just wondering what the likely hood of both pumps going wrong at the same time.

    Ive ordered up two fuel filters and will again remove the old ones, cut them open and see if theres any crud in them that could also point to this.
     
  16. spiderscott

    spiderscott Formula Junior
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    Finally the other part that seems to be a potential issue is the Fuse board and been burnt be overloading. Ill remove the terminal and check for any signs. If required Ive remove the board strip it down and check deeper.
     
  17. Cribbj

    Cribbj Formula 3
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    Scott, no the inertial switch (if it's there) will be close to the battery, same area as your rotary battery disconnect switch. It's an electro-mechanical device that stops the fuel pumps in the event of a high inertial impact. You're looking at the standard roll over valves for the fuel tank - not the same thing.
     
  18. ferraridriver

    ferraridriver F1 Rookie
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    yes
     
  19. spiderscott

    spiderscott Formula Junior
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    Bit more research and found this on a F348 (same era) site:

    Bosch relays (as used on Ferraris and various other makes of cars) number their metal pins with a standard category system.

    PIN # = Standard

    15 = Switched positive output from battery
    30 = Postive output direct from battery (+)
    31 = Direct to battery negative ( - ), ground
    31b = Return to battery negative via switch or relay
    49 = Positive input for turn signal flasher
    49a = Turn signal flasher trigger power to switch (54); marking used after /5
    54 = Turn signal switch contact from flasher (49a); marking used on /5
    85 = Relay trigger wire, generally for negative/ground winding on electromagnet
    86 = Relay trigger wire, generally for positive winding on electromagnet
    86a = Path to ground via neutral switch with diode (prevents "NEU" from lighting via clutch switch [contact 86] )
    87 = Normally open relay output, generally
    87a = Normally closed relay output
    87b = Second normally open relay output on a seperate throw
    D+ = Voltage Regulator/Dynamo (Alternator) positive
    C or KBL = power to turn signal indicator light in gauge cluster

    So I have jumped between pin 30 & 87

    Result: When i touch one of the jump wire on pin 87 I can hear the furl pump click in and out
    second relay I cant hear anything.

    Its quite difficult doing this alone, I need a second set of ears to verify.
     
  20. spiderscott

    spiderscott Formula Junior
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  21. spiderscott

    spiderscott Formula Junior
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    Thanks.

    Ive had a major hunt and for some reason it looks like the 456 does not have the inertial switch ?


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  22. spiderscott

    spiderscott Formula Junior
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  23. spiderscott

    spiderscott Formula Junior
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  24. spiderscott

    spiderscott Formula Junior
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    does anyone have a WSM and wiring diagrams for the 456 they can ping me over ?
     
  25. Cribbj

    Cribbj Formula 3
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    Sorry Scott, I didn't realise you had a '97 456. I think this inertial switch only came on the M cars which had the 5.2 Motronic setup, similar to the 550's. Maybe a knowledgeable early 456 owner could jump in and enlighten us?
     
  26. ferraridriver

    ferraridriver F1 Rookie
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    Why don't you jump the pump itself just to make sure unless your positive the pumps are running by jumping the relay.
    It's so simple and it will tell you if it's a fuel pickup or filter blockage problem.

    If a pump is running you should have fuel at the schrader valve. You should be able to hear the pumps run.
     
  27. tazandjan

    tazandjan Two Time F1 World Champ
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    John- The 97s all had 5.2 so they could pass the Jan 1996 OBDII requirement. In the US, only the 95s had 2.7. But I did not see anything in the OM for the 97 GT/GTA that showed an inertial switch. They do show an inertial switch on the 456M, though. Might be on the 5.2 456s, as well.



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