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Still can't start my 308 - help!

Discussion in 'Technical Q&A' started by markrolf, Feb 2, 2004.

  1. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    I've posted about this before, but I'm still having no luck. The car (1981 308GTBi) will not hot start. It's perfect from cold, but will just turn and turn when hot.

    So far, I've replaced:-

    Starter Motor
    Warm up regulator
    8 Spark plugs
    Both sets of HT leads
    Rotor arm (1 bank)
    HT Lead extensions (all 8)
    The FI mixing chamber (under the air filter) has been cleaned out

    I've been told by my local dealer that all fuel pressures are holding and are perfect when the car's running. Also all electrical readings on the leads etc are excellent. Emmissions are also spot on.

    After changing all the electrical items, the car will just about come to life, but it takes a long time, and doesn't sound healthy. Also, for the first time yesterday, it backfired whilst I was trying to start it!

    Does anyone have any ideas 'cause I've totally drawn a blank now!!

    Many thanks,

    Mark
     
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  3. ferrarifixer

    ferrarifixer F1 Veteran
    BANNED

    Jul 22, 2003
    8,520
    Melbourne
    Full Name:
    Phil Hughes
    First you need to properly diagnose why it won't start.....fuel or spark? Can you smell fuel from the exhaust when it fails to start.

    Check the thermo-time switch, (NOT the water temp gauge sender) that controls the cold start injector. It could be opening the cold start injector even when hot. Too rich.

    Make sure the injectors are free.....when it does start, does it run on all 8, or about 5/6 for a while?

    Check the crank sensors. Remove them. Clean them, and check their resistance is 700-1200 Ohms at all times.

    Check the terminals that connect the crank sensors. The "bullet" type open up and cause high resistance/open circuit.

    Check the block connectors near the oil cooler, for crank sensor resistance again.
     
  4. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    Do you normally check for crank sensor resistance near the oil cooler on the large wiring harness or do you go right to the sensors 2 wire connector?
     
  5. KKSBA

    KKSBA F1 World Champ
    Rossa Subscribed

    Oct 31, 2003
    13,804
    SBarbara-La Jolla CA
    Full Name:
    KKSBA
    I had a hot start issue also. Although 8 seconds of cranking always would get it to fire. Fuel pressures checked ok before and after shutdown, but the injectors were found to be bad. They were leaking fuel into the engine after shutdown and flooding the engine.
     
  6. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Check the fuel pressure readings you have against this data :-

    Fuel pump delivery at least 750cm³/30s
    Warm control pressure 3.4 - 3.8 bar
    Primary pressure 4.5 - 5.2 bar
    Leakage test, pressure must be minimum 1.7 bar after 10 minutes and 1.5 bar after 20 minutes
    Injectors opening pressure 2.5 - 3.6 bar

    Depending on what type of thermo timeswitch you have fitted the resistance value will vary, if you let me know what type you have I should be able to give you some figures. There will be a number engraved on one of the hexagonal flats on the switch - it will be something like 35° C/8s or 18° C/8s or similar.


    MW
     
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  8. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    Thanks guys.

    Ferrarifixer, no there is no smell of fuel. I believe there's fuel and spark, pretty much most of the mechanics have been replaced or checked.

    This morning, I took the car for a 20 mile run to get it hot, turned it off for 20 mins, came back to it and it flatly refused to fire. It just turned and turned. Throttle, no throttle, made no difference.

    I opened up the bonnet and took off the blue plug (think it's the cold start injector, attached to the top of the plenum chamber and near the warm up regulator), the car then fired. Not cleanly, admittedly, but it got me home!!

    So my thinking is something is that it it's something to do with this. Can this flood the engine?

    Someone else also mentioned about leaking injectors too...another option!!

    Malcolm, I've had all the fuel pressures checked out, the holding pressures were fine (so I'm told!). I'll have a look at the thermo switch. Am I right thinking that it also feeds the cold start injector?

    Thanks chaps - much appreciated, I've had this thing for a year and no one seems able to fix it!!!

    Mark
     
  9. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Mark,

    Yes you are correct, the thermo-time switch has two connections,
    W & G. "W" goes directly to the start valve and "G" goes to terminal 86 on the Bosch relay number 1.

    To make it clearer see diagram below.




    MW
     
  10. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    Malcolm,

    Have you got these relays in stock. I think it's worth replacing them and seeing if that helps

    Thanks

    Mark
     
  11. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Mark,

    Your particular car has one relay, according to to my manual it is a Bosch relay number 03320150061. Our part number is 40130007 which is a Bosch relay 03320191510. I don't see any problem with this as both are the same spec.
    BTW I have given Mark this info.


    MW
     
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  13. Prancing_Horse

    Prancing_Horse Formula Junior

    Dec 23, 2003
    528
    Arlington,VA
    Full Name:
    Dan
    this may saound crazy,


    but does it have gas in the tank
     
  14. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    Oh yes, plenty of the good stuff !!

    I wish it was that simple!

    Mark
     
  15. Wayne 962

    Wayne 962 Formula Junior

    Nov 27, 2003
    434
    Hi all. I'm not familiar with the 1981 CIS system, but I know the symptoms from the CIS Porsches.

    The hot start problems are almost always caused by the fuel accumulator, which is supposed to hold pressure in the system when the engine is off. If it fails, you almost always have a hot start problem. Working in conjunction with the accumulator is the check-valve inside of the fuel pump. I would suspect it's either one of these, assuming that your car has them...

    -Wayne
     
  16. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Mark,

    What Wayne is saying is a possibility, thats why I mentioned checking the "leak down" figures.

    I found this artical in an old Bosch manual.

    MW
     
  17. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
    1,527
    UK
    Full Name:
    Malcolm W
    Text for picture above.


    MW
     
  18. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    Thanks Malcolm and Wayne,

    Your input is much appreciated.

    I've ordered some parts from Mark (Ferrari Uk), such as cold start injector and thermo valve which may help - who knows!

    I'll certainly go down the accumulator line if these fail to change anything. To be honest, that's about the only thing that hasn't been changed in the whole system!!

    Best regards,

    Mark
     
  19. MarkG

    MarkG Formula Junior

    Nov 3, 2003
    369
    Colorado Springs
    Full Name:
    Mark
    When searching archives you will find vast majority of hot start issues to be fuel accumulator related.

    I did a pro-active replacement of both my fuel pump and accumulator last summer ('82 GTSi).
     
  20. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,993
    Groton, MA
    Full Name:
    Verell Boaen
    Mark,
    The last sentence puzzles me. Did they measure the fuel pressure after the car was good & hot & then stopped? If not, that's a key test for a bad fuel accumulator. What should happen is that when the engine's turned off, the injectors will quickly bleed the pressure down until it's just below the fuel injector's 'opening' pressure. The accumulator will sustain that pressure for quite some time w/o further drop.A bad accumulator will let the fuel pressure drain down to about zip in a few minuites. Another source off bleed-down is an injector that's sticking open.

    (Well, the really definitive accumulator test is the no-brainer of looking at the little drain tube on the back of the accumulator (on the US ones you have to pull a hose off). If it's dripping gas, or the hose is full of fuel, then you've got a bad accumulator.

    BTW, I bought an exact replacement BOSCH accumulator:

    Subject: re: Requesting price quote: BOSCH 0 438 170 004
    Date: Thu, 4 Sep 2003 17:43:46 EDT
    From: PartWerks9@aol.com
    To: Verell@Boaen.com

    $119.95 new. Shipping is about $6.00

    Of course it didn't come in a nice yellow box w/a horsie on it...
    Also bought an exact repl. fuel filter from AutoZone for about $15.
    Not BOSCH, but both original & the replacement looked identical & were steel stamped 'made in Israel'. - Wanna bet that there are 2 different filter mfgs in that little country...
     
  21. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    Hi Verell

    Thanks for your input. I'm not entirely sure what was tested. I was told the holding pressures were checked and found to be good. I'm going to try fitting these other parts that I mentioned earlier, then definately try a accumulator.

    Maybe one day, I can take it out and not get stuck !!!

    BW

    Mark
     
  22. Trinacria

    Trinacria Formula Junior

    Aug 7, 2002
    665
    Long Island, NY
    Full Name:
    Baldassare Guzzo
    Mark, check your mail. I need your email address or your real address. PM me when you can. File to big to post here with out making it to small to read.
     
  23. Tifosi1

    Tifosi1 Formula 3

    Feb 17, 2002
    1,560
    Pearl River, LA
    Full Name:
    Kelly J. Vince
    Mark, do you notice that the car will start, but when it is warm it will not start. Do you have to ait until the car is cold before it starts.

    This happened to me, I would have to wait 1 hour unitl I could start the car. I replace the themal time switch and it did the same thing. So, I've unpluged the cold start fuel injector electrical cable and it has started ever since.

    Good Luck,
    Kelly
     
  24. markrolf

    markrolf Karting

    Nov 26, 2003
    116
    Kettering, UK
    Hi All,

    Ok, the dealer came back out to look at the car during the week, and the damn thing started for them! I couldn't believe it!

    They said to use about an inch of throttle when hot starting and this should work. So far, it has - just, and I mean just. It really does not want to start and chugs into life - surely not the way Enzo would have designed it! I still don't trust it.

    I'll try taking the feed to the cold start injector off, but a new one should be arriving today anyway.

    Thanks to all.

    Mark
     
  25. Wayne 962

    Wayne 962 Formula Junior

    Nov 27, 2003
    434
    Accumulator and/or check valve. Check the fuel pressure inbetween the two (with a gauge) when the car won't start. You will probably find it very low, which can lead to vapor lock (the fuel evaporates, and can't be pumped)...

    -Wayne
     

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