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400i Starting Problem

Discussion in '365 GT4 2+2/400/412' started by Santa Fe Jeff, Nov 15, 2019.

  1. Santa Fe Jeff

    Santa Fe Jeff Rookie

    Mar 6, 2015
    17
    Santa Fe/Conroe
    This is the car from the recent BaT thread. I had Craig do a once over on it before picking it up and it ran awesome. He had fixed the oil leak (not a rear seal, some sort of oil vapor collector in the V?), A/C and a number of other minor things so the car was good.

    Made it from Portland to Mt. Shasta with no problem. Started the next morning (38F) with some stumbling but cleared out shortly and ran great to Vacaville where we got gas. A little more cranking to start it but it did fire up. Drove to Richmond with no problem but after sitting for 30 minutes, no start. Zip, zero. Simply cranked and cranked with no fire at all, even a miss fire. So we started checking for fuel and spark in the obvious places.

    1) Fuel appears at the main feed from the tank lines under the big banjo bolt
    2) Fuel burps out of the banjo bolts on the lines to the fuel injectors
    3) Initially at one point the fuel pumps were not working but this was resolved when we pulled the fuses in and out and also disconnected the roll over plug on the driver side fuel distributor.
    4) There is spark at the spark plugs. We pulled out several and grounded them while cranking. Got a spark although it appeared to be sort of week.
    5) Plugs appear to be dry, i.e., no flooding
    6) Cranking voltage is 11.1 VDC

    When the car is warm, absolutely no indication of ignition, simply cranking with no firing (like cranking an engine without the plugs installed).

    Same situation but this time we shot a blast of starting fluid into the inlet horn with the throttle at full open. A brief stumble but then it fired right up and idled perfectly! We let it warm up and charge the battery (13.9 VDC) for a few minutes, shut it off, and tried again without the starting fluid and it just cranked and cranked with no starting again. Gave it a blast of starting fluid and it fired right up and idled fine, runs great.

    So what's up?

    Do I just have a weak spark? Would the difference from 11.1 VDC to 13.9 VDC make enough of a difference that the mixture wouldn't ignite until we splashed it with starting fluid? Do the Dino-thingies get tired?

    Any suggestions?
     
  2. raemin

    raemin Formula Junior

    Jan 16, 2007
    320
    Lyon (FR)
    Full Name:
    R. Emin
    #2 raemin, Nov 15, 2019
    Last edited: Nov 15, 2019
    Cannot give you definitive answers here as this is a problem I did not have so far on my car. On my cousin 412 (that has different pumps), there was a leak in a hose, the car was lacking power at full throttle and would not start when hot.

    The fuel pumps do not work the same way when the car is cold or hot. The idea is that when the car is hot, accumulator are supposed to provide the required gas pressure (not the fuel pumps). If you've got a leak somewhere, the pressure in the accumulator will not be sufficient so as to feed the injectors.

    There are two relays for the pump, plus a master relay that can deactivate the other two. When the car is cold this relay just lets the pump work, but when the car is hot it will shut off the pump until some airflow is sensed on the K-jet. You should just have a look at the wiring diagram that highlights the 3 relays, the airflow sensor, thermo-switch, cold valve switch and start valve timer. All these are involved during a hot-start...

    I let others further describe this, but the first place I would be looking for is a leak. For testing purposes there are some possibilities to bypass the hot/cold control (see comments in this forum on how to disconnect the airflow sensor, that's the green plug on the k-jet)

    As a side note: if the battery is weak, do not jump-start the car as the dinoplex will be fried.
     
  3. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,831
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    Brian Crall
    If it is not holding residual pressure they can vapor lock easily especially with reformulated gas. If the battery is strong enough giving it full throttle and cranking a while should start it. Your starts with starting fluid strongly suggest this is the issue.
     
  4. Al Campbell

    Al Campbell Formula Junior
    Silver Subscribed Owner

    Nov 22, 2013
    411
    Australia
    There is also a cold start injector on each bank that gets power for cold cranking & pulsed power for hot starting. I had problems with mine previously not getting the pulsed power when hot starting & it had the same symptoms you describe. There is a relay that supplies the pulsed power (similar to a blinker can but pulses twice as quick) in the relay block. My relay had a dry solder joint on an electrolytic capacitor causing it to fail. I replaced the capacitor & reflowed the solder joints & all good again. :)

    Cheers,
    Al

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  5. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Owner Consultant

    Dec 26, 2001
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    If its a hot re-start problem (only sat 30 minutes) its losing rest pressure. There are a number of things that will cause it to lose its rest pressure which I wont bother listing. Shooting it with ether to get it to run is a very good indication thats your problem.

    And I now see Brian wrote pretty much the same thing! Next time Ill read the entire thread.
     
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  6. Santa Fe Jeff

    Santa Fe Jeff Rookie

    Mar 6, 2015
    17
    Santa Fe/Conroe
    Really good answers I'll check it all out when I get back home. One question, is California fuel more prone to vapor lock than the rest of the states? The problem started after my first full up in Mt. Shasta and got worse after a fill up in Vacaville. And when you say a leak, is that internal or out on the road?
     
  7. Newman

    Newman F1 World Champ
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    Dec 26, 2001
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    Internal back to the tanks
     
  8. rovexienus

    rovexienus Formula Junior
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    Jun 10, 2010
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    Sainte Colombe, France (near Lyon)
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    Jean-Michel Savary
    Agreed, I had this situation of no start on a hot engine, in this particular case it was eventually traced down to a leak in the pressure accumulator. In summary if the start was a minute or so after shut down, no problems (residual pressure was still good enough), if the start was 10 minutes after shut down (for example a refill at the gas station), no start at all, the only way was to wait long enough for the engine to be sufficiently cold for the cold injector to work and start the engine. Like Paul said all scenarios of pressure losses (fast or slow) are possible.
     
  9. Newman

    Newman F1 World Champ
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    Dec 26, 2001
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    If you're stuck in a situation like that unplug the fuel pump switch on the sensor plate housing and push the sensor plate down with your hand, key on. It'll prime the system, you'll hear the pumps come on. Then attempt to start the car.
     
  10. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Jan 11, 2001
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    Don't think you need to do both actions, Paul - either:

    1. Unplug the safety switch on the sensor plate housing + key "on" = fuel pumps run

    or

    2. Key "on" + push the sensor plate down on the sensor plate housing that has the safety switch = fuel pumps run

    I prefer #1 as it can be done fully-dressed with no tools and little risk of getting dirty ;)
     
  11. Jasonberkeley

    Jasonberkeley Formula 3
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    Apr 23, 2017
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    When I had hot start problems did a few things which solved the problem.

    - replaced fuel pumps
    - tested fuel injectors. Leaking. Replaced with new.
    - fuel distributors leaking at o-rings. Rebuilt fuel distributors.

    Then had a bit of a cold start issue, which was solved by rebuilding the warm-up regulators.
     
  12. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
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    Or into the cylinders.
     
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  13. rovexienus

    rovexienus Formula Junior
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    Jun 10, 2010
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    Sainte Colombe, France (near Lyon)
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    Jean-Michel Savary
    Thanks Paul, that sounds much better than waiting for one hour at the gas station!
     
  14. Al Campbell

    Al Campbell Formula Junior
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    Nov 22, 2013
    411
    Australia
    The fact that you can crank & crank with no fire at all indicates to me that the start-up injectors are not getting fuel or power.

    All these other issues can be a cause of poor starting but if the start-up injectors are functioning you should be getting the odd kick of life. The fact that a squirt of starter fluid & it starts & runs fine says the fuel pressure must be there so I would look at the electrical side of the start-up injectors.

    The K-Jetronic is a mechanical fuel injection which relies on airflow through the conveyors to move a plate which moves the metering piston in the fuel distributors to control the flow to the injectors. The original starter motors crank the engine at a very low speed so start-up injectors are required to give an initial charge of fuel to get the engine to kick over & bring the mechanical fuel injection into play.
     
  15. Newman

    Newman F1 World Champ
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    Not correct. If the engine is warm the COLD START injectors are off line and they only inject during cranking using the starter solenoid as the trigger. Using ether does the same thing the cold start injector would do, fills in the gap until the mechanical system can take over. A cold start the next day would have no rest pressure or very little so the cold start injectors are needed even if its mild out.
     
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  16. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
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    Not when hot. There is sufficient displacement of the plate at cranking speed when the engine is hot to start the car. There is a reason Bosch referred to the start injectors as "Cold Start Injectors".
     
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  17. Al Campbell

    Al Campbell Formula Junior
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    Nov 22, 2013
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    Australia
    Sorry if I have mislead or upset anyone but I have experienced the exact same symptoms as the original post & in my case it was relay 1 that rectified the problems. I just thought I would offer this advice as it is a quick & easy thing to check before going through the more expensive & time consuming process of fitting new accumulators etcetera that I went through before fixing this fault.

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  18. raemin

    raemin Formula Junior

    Jan 16, 2007
    320
    Lyon (FR)
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    R. Emin
    Your relay box looks like a generation 1, not the failiure prone one that can be found in the gen2 / 412.

    My car was a late gen1 400i (january 1982) with double alternators, but I do not have this additiobal relay, which year is yours?
     
  19. Al Campbell

    Al Campbell Formula Junior
    Silver Subscribed Owner

    Nov 22, 2013
    411
    Australia
    Thanks for this info it is very interesting.

    I have two 1980 cars & both have relay 1.
    I also have a 1982 one which is apart for restoration. I just checked this one & it does not have a relay one. It appears that Ferrari made a change between these years to increase the duty cycle for the start-up injectors whilst warm cranking from around 50% to 100% duty cycle to make warm starting easier. I might retrofit this upgrade to the earlier cars sometime.
     
  20. wrxmike

    wrxmike F1 Veteran
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    Mar 20, 2004
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    The problem is probably insufficient fuel pressure to crack open the Bosch injectors. The K Jetronic system needs a high enough fuel pressure to work. The cause of low fuel pressure will most likely be electrical, ie not enough current to the fuel pumps, caused by a problem in the fuse box. Low current will allow the pumps to run, but not produce enough pressure to crack open the injectors.

    The fuel system in these cars is essentially duplicate, so if you had 1 dead fuel pump, or clogged filter, etc, the other side of the engine would still attempt to start and run, (they will run as a 6 cylinder :) ).

    Also you have enough spark to run the engine ( runs with starting fluid )
    And your plugs are dry ( symptom of not enough pressure to crack the injectors ) , assuming there is petrol in the tank :)

    You can take move the high current fuel pump circuits off the fuse box and use the original circuits just to switch some new seperate high current relays you install for the fuel pumps to ensure enough amps reach the fuel pumps.

    M
     
  21. raemin

    raemin Formula Junior

    Jan 16, 2007
    320
    Lyon (FR)
    Full Name:
    R. Emin
    To be honest I wouldn't do that on a generation 1, as the relay-box is much better than on the newer models. The relays are directly bolted on the harness and are not passing through the cheap PCB that can be seen on later (gen2 & 412). That's even more obvious for the fuel-pump relays: see on Al Campbell diagam, it is super easy to crimp new relay terminals on relay 1,2,3,4,5 (as a last resort).

    Also on generation 1, if you bypass the stock harness, you bypass the ammeter readings, and as the pumps are what draw the most, the ammeter becomes useless.

    As per Al Campbell suggestion one can also use the very silver grease he suggested a few months back (Thanks for the tip by the way:) ), this will cure most high amperage related issues on a generation 1 car.
     
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  22. james.colangelo

    james.colangelo Karting

    Jan 28, 2008
    212
    Detroit, MI USA
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    James Colangelo
    I have this exact same problem Jeff - So far I have replaced my coil and my distributor cap, but I have not been driving my car regularly. I'm going to be following this post in earnest. I have a feeling this issue will rear its ugly head again.

    Also Jeff I'm very curious about your oil leak - I'm going to send you a PM!!

    Jim
     
  23. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,202
    Romulus, NY (Finger Lakes)
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    Ken Battle
    Jeff asked, "One question, is California fuel more prone to vapor lock than the rest of the states? "

    CA has tight limits on maximum vapor pressure of fuels and therefore should be less prone to vapor lock, unless you are in the middle of a wild fire.
    Ken
     
  24. Santa Fe Jeff

    Santa Fe Jeff Rookie

    Mar 6, 2015
    17
    Santa Fe/Conroe
    Again, thanks for the input, I'll start checking tomorrow.
     

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