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stumped 85 308 wont start

Discussion in '308/328' started by fer308qv, Aug 14, 2021.

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  1. fer308qv

    fer308qv Karting

    Jul 12, 2006
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    #1 fer308qv, Aug 14, 2021
    Last edited: Aug 14, 2021
    Went to start it today and it just cranks strongly. Backgroung info: Had an occasional issue with hard starting mostly when hot, but always started. Recently corrected typical slow window problem and replaced an audio system. Car ran fine after that work. Coincidentally 2 battery tenders were burned out this morning one plugged into the ferrari
    When cranking I didnt smell any fuel, and didnt hear the electric fuel pump. I checked the fuse, and saw there was none?! Also no terminal connectors which ive seen on other pictures
    (First block 3rd fuse 16A) WTF! ok must have been josseled out and eaten by gremlins. Replaced it but stlll nothing. ????
    My next step is to replace relay.
    I believe I should hear fuel pump with the key on?

    Any input appreciated.........
     

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  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Aug 14, 2021
    Not uncommon for that fuse position to have trouble/get crispified because the (normal) CIS fuel pump current is quite high (~10A). Yours has obviously had some wiring modifications/repairs if your fuel pump worked without that fuse present.

    No. Do a search using something like "safety switch fuel pump" for many prior threads.
     
  3. fer308qv

    fer308qv Karting

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    #3 fer308qv, Aug 14, 2021
    Ok .additional clues........
    The missing fuse and lack of terminal connectors in its original place could explain the added fuse holder with a 30 amp agc fuse?
    Im thinking now that the hanging tan wire came loose from its replacement connection.
    Im so tempted to reconnect and try.
    Does anyone have a schematic that shows the wire color for the fuel pump?

    With any luck this is the problem and possibly the root cause of my occasional hard start problem with that poor connection
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  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #4 Steve Magnusson, Aug 14, 2021
    The schematic for a 308QV is in OM (near the back). The always +12V large red wire is what is normally connected to the top of fuse #3, and the beige wire connected to the bottom of fuse #3 routes that +12V power to the fuel pump relay (which connects it to the fuel pump motor when the fuel pump relay is closed). Looks more like the wire conductors of the beige wire have been broken off from the vibration (having that added fuse holder being unsupported) rather than them coming loose from the yellow crimp connector.
     
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  5. fer308qv

    fer308qv Karting

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    #5 fer308qv, Aug 14, 2021
    Thanks Steve. I will "reattach" and cross my fingers. Its fuse protected for what thats worth...........
     
  6. fer308qv

    fer308qv Karting

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    #6 fer308qv, Aug 14, 2021
    That was it Steve! Thanks for confirming the wiring so quickly
    I guess reconfiguring the fuse holder was a result of a bad fuse block. Strange because it looks mint. And it failed over 25 years ago because thats how long ive owned the car.
    I guess I better look into replacements sooner than later..
    Now I will monitor the occasional hard start problem. Hopefully it was caused by the poor fuel pump connection.
     
  7. thorn

    thorn F1 Rookie
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    #7 thorn, Aug 14, 2021
    I highly recommend replacing those vintage fuse blocks with modern versions - and while you're in there, do what you can to remove some of those bad wiring hacks.

    I truly despise butt splice connectors.
     
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  8. absostone

    absostone F1 World Champ
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    #8 absostone, Aug 14, 2021
    newark_308 and built2grind like this.
  9. Dave Bertrand

    Dave Bertrand Formula Junior
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    #9 Dave Bertrand, Aug 15, 2021
    As do I. I'd recommend the OP remove those, and solder the wires together instead, and protect the connections by shrink tube.

    On another note, is 30A the right size fuse to protect that circuit? Seems kinda high. On the 328, the fuel pump is a 15A circuit.
     
  10. thorn

    thorn F1 Rookie
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    #10 thorn, Aug 15, 2021
    The largest fuses in the blocks are 16 amps. (15A works fine if you've upgraded the blocks.)

    30A is risking bad things.
     
  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #11 Steve Magnusson, Aug 15, 2021
    I'd agree with that -- a 30A fuse there really only protects against a very high current dead short, and you could have a situation where the wiring melts before the fuse blows ;).

    Although a 15A fuse doesn't give much margin for a device that draws ~10A when working correctly, and has a much higher inrush current at start-up. Fuses are a thermal device, and it could be that extra heating from a bad connection in the fuseblock was causing the 15A fuse to blow (even though the current was actually OK) so the prior Owner just went up to higher fuse values to "solve" the problem (that still kept blowing) when the real trouble was with the fuseblock itself. Once he/she made the modification, he/she (wrongly) stayed, or went, with a 30A fuse. 15A should be OK, but using a 20A fuse in that remote fuse holder would be no serious sin IMO.
     

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