Dino blowing engine fuses | FerrariChat

Dino blowing engine fuses

Discussion in 'Technical Q&A' started by ghenne, Jul 24, 2004.

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  1. ghenne

    ghenne Formula Junior

    Mar 8, 2004
    461
    Toronto, Canada
    My 1972 Dino keeps on blowing the 60 amp engine fuse on the firewall. It doesn't do it immediately: it takes 30-60 miles of driving before it happens.

    Any ideas where the problem might lie?
     
  2. ferrarifixer

    ferrarifixer F1 Veteran
    BANNED

    Jul 22, 2003
    8,520
    Melbourne
    Full Name:
    Phil Hughes
    Voltage regulator....up front by the spare wheel

    Or, cable shorting to ground somehwere on alternator or battery, or ammeter.
     
  3. cmparrenzo

    cmparrenzo F1 Rookie

    Mar 3, 2002
    2,687
    Kansas
    Full Name:
    Chris Parr
    Thank you! Mine just did that this weekend! Now I know what to look for!

    Chris
     
  4. ghenne

    ghenne Formula Junior

    Mar 8, 2004
    461
    Toronto, Canada
    Sounds promising. Other than swapping another voltage regulator in, is there any way to test which it might be?
     
  5. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,879
    Perhaps there is another answer. I do not believe that a faulty voltage regulator will result in a blown fuse. The regulator merely "regulates" the field current, thereby modulating what the alternator generates.

    The blown fuse indicates a low resistance to ground (another way of saying - a short circuit to ground). As the 60-amp fuse interrupts the large conduit going directly from the altenator, through the ampere meter to the battery, I would check that bad-boy for worn insulation. I suspect that there is something rubbing against one of the ampere meter lugs. If nothing is touching the ampere meter, then check the large diameter conductor leading from the ampere meter to the battery (and around the ignition switch).

    Furthermore, my voltage regulator in the Dino is under the dash - red box, three connectors.

    Finally, I believe that a bad battery cell might offer a low resistance to ground (if the lead plate has collapsed). Check the battery.

    Jim S.
     
  6. solly

    solly Formula 3

    Jun 2, 2001
    1,148
    Westchester NY
    Full Name:
    Dr. Steven S.
    My generator light has been going on, with the ammeter reading discharge for the past year. After a few miles of driving the light would go off, and the ammeter would read charging.

    A month ago the light did not go off, and the ammeter read discharging, so I went home and called my Ferrari service guy. He recommended checking the 80 amp (not 60 amp) fuse in the black box on the firewall. There was nothing wrong with it, so I cleaned it cleaned the contacts, reinstalled it, and the problem went away immediately.

    Today it happened again, the red light stayed on for about 15 minutes, then went out, then the ammeter went to max positive charging (+40) for a few minutes, then died again. When I got home the small 8 amp fuse in the box was blown. I swapped the whole box and fuses for a new spare I had, but this did not cure the problem.

    What do I check next before attempting to change the alternator? What wires should I check for grounding. The big fuse has not blown. I used an inductive meter to check for current at the top and bottom of the fusebox, both showed current. However, the large wire on the lower left (that connects to the bottom of the 80 amp fuse), which I presume goes to the alternator showed no current.

    What else can I check to make a definite diagnosis?
     
  7. ghenne

    ghenne Formula Junior

    Mar 8, 2004
    461
    Toronto, Canada
    When they traced everything back, they found two problems. The voltage regulator (it's a red plastic box under the dash) was malfunctioning (outputting up to 18 volts, not 12) and the wires going to the tachometer were fried. The alternater also had to be rebuilt, but that was probably just collateral damage.

    Everything is running smoothly now.
     

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