456 GTA 1997 Wont start - need fuel system expert

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.

 

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.

 

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?

 

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

 

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

 

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)?

 

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

 

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.

 

Cheers, Ive been a long standing member on here for many years, just new to the 456 V12 circles . 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.

 

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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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

 

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

 

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.

 

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.

 

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.

 

yes

 

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.

 

Fuse board:

I have pulled all the connectors and inspected, cannot see any obvious burn marks. So for now I will look elsewhere and come back to this for a strip down if no joy
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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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mmmm hang on .....

More digging has uncovered this:

Parts wise 163675 or 179087 is the common part number used by ferrari in that era of cars for the inertial switch

I can see its on the 456 MGTA and M Gt cars listed in parts but not in 1997 GTA ?

Its in the fuse board zone area so I will have a look again tomorrow in the daylight
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tested the fuel rails while jumping the relay

no fuel at all !!
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does anyone have a WSM and wiring diagrams for the 456 they can ping me over ?

 

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?

 

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.

 

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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