Hard starting when warm | FerrariChat

Hard starting when warm

Discussion in '308/328' started by Davvinci, Jan 11, 2010.

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  1. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    80 308i starts great when cold but once it warms up, the throttle must be opened about 50% to start in 3 to 4 seconds. Runs great once started. Normal for the K-Jetronic? Fuel pressure must be good. Can hear bypass dumping into tank when safety disconnected. Valves reset, new belts, wires and plugs. All oils new. Any ideas?
     
  2. speedy

    speedy Formula Junior

    Oct 18, 2005
    625
    Plano, TX
    Full Name:
    James Gardner
    Warm Up Regulator is probably bad.
     
  3. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    Just replaced water temp regulator (if this is the same thing) and rebuilt the water pump. Has never run over 195F since I've had it and warms up in just a few minutes. Cold start throttle kickdown takes about three minutes.
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,785
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Not necessarily. The operating fuel pressure is OK (because, as you say, it runs well once running), but the residual fuel pressure after shut-off must not fall too quickly to a low value; otherwise, warm restarts will be difficult -- see page D43 in the Mondial8/QV WSM 281/83 for specs.
     
  5. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    If a man lives long enough, his protrate will fail, if you own your 308 long enough you will encounter 'warm start failure'.

    There are several well known causes for this complaint. If your thermo start timer is bad, disconnecting the cold start injector will cure that cause. The cold start injector is at the right end of the plenum and is used only to inject gas for a few seconds into a cold engine. I.e. it should never inject gas into a warm engine, which is what the thermo-timer regulates.

    Other causes of warm start issues include lack of pressure in the system. It can come from bad back flow regulator in the fuel pump system and a bad accumulator, both of which fail to maintain proper gas pressure when the engine is shut down. These are best diagnosed using a pressure gauge at the fuel distributor.

    Check this post for more reading material http://www.ferrarichat.com/forum/showthread.php?t=250491
     
  6. PV Dirk

    PV Dirk F1 Veteran

    Jul 26, 2009
    5,401
    Ahwatukee, AZ
    I had a warm start problem, someone suggested letting vehicle idle for a bit before shutting off. I let it idle for 10 to 20 seconds when I come to a stop. Seems to start fine now. Might just be coincidence. I think it was suggested my accumulator might not be up to snuff and this was a temp fix. Really don't remember, but worth a try and it's cheap.
     
  7. zeiglerr

    zeiglerr Karting

    Oct 23, 2009
    69
    Lansdale, PA
    Full Name:
    Reid Z.
    The original '80 fuel pump had a check valve at the outlet and it was eliminated in about '82 so newer fuel pumps don't have it. Without it the system can't maintain system pressure with the pump off. If that might be the problem, let me know and I'll chase down the sources for the parts. Simple fix. -Reid
     
  8. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    I had a new fuel pump sent to me (but not an accumulator) which had a different check valve but the threads were not the same on both ends (of the check valve or outlet) and a conversion could not be found. So I put the old one back in (not knowing if it was bad) and tested it by finding a thread on FChat that told me to remove the connection. I will definitely put a pressure gauge on the inlet side of the fuel distributor to check if the pressure goes down. That will give me an actual pressure of the system bypass because I could hear the gas actually splashing into the tank. Suffice it to say that this slow start is NOT normal.
     
  9. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    Thanks. I will try this to see if it makes a difference.
     
  10. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    Thanks for this. I am into replacing the parts that MIGHT be bad because knowing the car is 30 years old is a little disconcerting on the longer jaunts (which have been few since it has been finished). Trying to keep it within my 100 mile tow limit until I have a little more confidence.
     
  11. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    I am a newbie to the site and don't know how to get to that page. But tell me once and I don't forget.
     
  12. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    That was the problem. Disconnected the cold start switch and cleaned out right away (the flooding). Tried to start it 5 minutes later and started right off. I will still go down and get the pressure checker for the inlet pressure to the distributor to make sure the check valve and accumulator are working properly. Going to order the thermo-time switch now though. Got a deadline on fixing this. Thanks
     
  13. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,785
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    You can download a .pdf copy of the Mondial8/QV WSM 281/83 here:

    http://ferrari.cdyn.com
     
  14. Davvinci

    Davvinci Karting

    Dec 11, 2009
    162
    California
    Full Name:
    DavidoSpeedo
    Thanks for all your help. More questions later, I'm sure. will post final result after parts arrive.
     

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