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1984 mondiel QV hard to start.

Discussion in 'Technical Q&A' started by Brian Gillies, Dec 29, 2020.

  1. Brian Gillies

    Brian Gillies Rookie

    Dec 29, 2020
    7
    Scotland
    Full Name:
    Brian Gillies
    Hi everyone

    I have just bought a 1984 3.0 QV mondiel and am have a problem with it. The car seems to take a lot of time to start. The emgine turns over no problem but doesn't kick until you pump the accelerator pedal a few times, even when warm. If you pump it to much it will flood the engine but when it does start it runs great. I know it has just had the caps and rotor arms replaced before I got it.

    I've never worked or anything like this before and just looking to see If there is anything common with them before I rip it apart

    Many thanks for any help and advice.
     
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  3. Steve Magnusson

    Steve Magnusson F1 World Champ
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    #2 Steve Magnusson, Dec 29, 2020
    Last edited: Dec 29, 2020
    Very common for the K-Jet equipped Ferrari like yours to have a warm restart problem, but much less common to have a cold start-up problem (and your post implies that you have that trouble, too) -- so you may have more than one issue to fix.
    One of the easiest things for a new K-Jet owner to learn how to do is to unplug the safety switch on the airflow metering unit. This will cause the fuel pump to run with just the key "on":

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    whereas, normally, with it plugged in, the fuel pump will run only: 1) during starter motor cranking or 2) if the key is "on" and the engine is actually drawing in air. So a simple test for a cold start-up is:

    1. Unplug the safety switch,
    2. Turn the key "on" -- you should hear the fuel pump run,
    3. With the fuel pump running, then turn the key to start, and see if it starts more easily without needing to pump the acc. pedal.

    If this does help cold start-up = you probably have a problem with the ...101 relay (Relay S - "Fuel injection delivery pump starting relay" per the 241/82 euro version OM) controlling the ...113 fuel pump relay.

    If no change in the behavior (and you are having a cold start-up issue), another thing to do would be to unplug the cold start injector and connect a 12V test light bulb to the two terminals in the harness connector -- during cold start-up motor cranking, the bulb should illuminate for a second, or two, and then go out. If it doesn't, you'd then need to dig into the Thermo-Time Switch operation (or really non-operation as that's the gizmo that should be providing this +12V pulse to briefly squirt the cold-start injector and add enrichment for cold start-up).

    Do you have a copy of the 241/82 OM if yours is a euro version 1984 Mondial QV?
     
  4. Brian Gillies

    Brian Gillies Rookie

    Dec 29, 2020
    7
    Scotland
    Full Name:
    Brian Gillies
    Thank you very much for the quick reply. I will check them out in the morning. It did come with a manuel but im not sure what one, I will also check that out. I think it is a euro version but i know very little about these cars so have alot to learn.
     
  5. GordonC

    GordonC F1 Rookie
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    Aug 28, 2005
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    Hi Brian, welcome to the forum, and congratulations on your 'new' Ferrari! Steve is one of the most knowledgable members here, so you will certainly benefit from his guidance.

    I would also suggest browsing or searching in the 308/328 and Mondial forum sections - while this section is called 'Technical Q&A', because it covers all models it's harder to find helpful history for the 3.0 QV cars. Most of the technical information and threads specific to these is in those 2 sections I mentioned.

    Oh, one more comment - pumping the throttle doesn't have any effect such as squirting extra fuel like with a carburetor's accelerator pump - "all" the throttle pedal does is open the throttle blade on the manifold. No more or less fuel is moved based on the throttle position when starting, just the amount of air is varied (which indirectly affects the fuel based on air flow through the K-Jetronic, but not like an accelerator pump).

    Regards,
    Gordon (a fellow Euro 84 3.0 QV owner, but in a 308 GTS)
     
  6. Brian Gillies

    Brian Gillies Rookie

    Dec 29, 2020
    7
    Scotland
    Full Name:
    Brian Gillies
    Thank you Gordon, I'm still trying to navigate my way through the site, but can't seem to find the mondial section. I'm using my phone so maybe that's the problem, I'll try my laptop later and see if that helps.

    I'm going to spend some time on the car this afternoon so hopefully find some issue's. I know what you mean with pressing the accelerator but it definitely makes a difference, I was thinking possible it was getting to much fuel and pump the pedal was giving it more air. I'm going to try a couple of different ways of starting it today and see what happens.

    Thanks again.
     
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  8. Brian Gillies

    Brian Gillies Rookie

    Dec 29, 2020
    7
    Scotland
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    Brian Gillies
    I would just like to thank everyone for there help and advice. I followed Steve's advice and noticed the safety switch on the air flow metering unit was disconnected and badly corroded. I replace the connector and plugged it back in, the fuel pump now only runs when cranking the key. I had the cold start injector unplugged to test the voltage but as soon I turn the key it fired up instantly. If I plug the cold start injector back in it won't start but as soon as I unplug it she starts within a couple of seconds. So it's look like the cold start injector is at fault.

    I will keep you all posted once I fit a new one.

    Thanks again.
     
  9. Steve Magnusson

    Steve Magnusson F1 World Champ
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    #8 Steve Magnusson, Dec 31, 2020
    Last edited: Dec 31, 2020
    Won't agree with that yet if what you described below happened during cold start-up.

    If this was during cold start-up, it's more an indication that the mixture is just way too rich. The cold start injector is supposed to squirt for a second, or, two during cold start-up. If that's making things so rich that it won't start either the manual mixture screw is set too rich or the cold control pressure is too low. Maybe the cold start injector could be "over-squirting" (so getting a new one is no harm, and, if that fixes things, great; however, it wouldn't hurt to confirm/deny the correct on-then-off electrical operation of the cold start injector during starter motor cranking and after releasing the key to run) -- but still think that you just have a way-too-rich problem (and unplugging the cold start injector isn't really a "fix" ;)).

    PS "...the fuel pump now only runs when cranking the key..." -- More importantly, now the fuel pump shuts off if you have a bad accident where a fuel line gets severed, you're unconscious in the Driver's seat, and the key is still "on".
     
  10. Brian Gillies

    Brian Gillies Rookie

    Dec 29, 2020
    7
    Scotland
    Full Name:
    Brian Gillies
    Hi Steve

    Yes I do agree with you, I just got a bit excited when it started so well. When I was checking it for voltage it only went to about 8 volts not a full 12 volts, but it did start exceptionally quick. I found some bad contacts in the fuse box and am fixing them first, once that is done I will do some further diagnostics and see what happens.

    Should it be a straight 12v going to the cold start and does it depend on how long it's cranks ?

    Thanks for all your advise.
     
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  12. Steve Magnusson

    Steve Magnusson F1 World Champ
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    No, it should be about the same voltage that the battery droops down to when the starter is drawing 150~200 A -- this might be as low as 9~10V. Throw in some small voltage drops for the many connections and the long small wiring = makes ~8V measured at the cold start injector connector not so unreasonable. For an extended cranking period, the battery voltage may continue to droop down even more and more, but this is not a normal situation -- on a working system, starter motor cranking is usually quite brief.
     
  13. Brian Gillies

    Brian Gillies Rookie

    Dec 29, 2020
    7
    Scotland
    Full Name:
    Brian Gillies
    It's seems you where correct Steve, I was going through the fuse box as there was some questionable wiring. I came across a few bad connection and some corrosion. After fixing these the car starts amazing both hot and cold. Fingers crossed I have rectified the problem. Thanks again for all your help.

    Ps any idea how I change the title as I have spelt mondial wrong .
     
  14. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
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    Steve Magnusson
    Glad that you got it sorted -- the F K-Jet models are old enough now that maybe every Gremlin hunt should start with "look for questionable prior mucking about with the wiring" ;)

    Don't think that you can correct the spelling in the title (even if done within the 20 minute editing window after posting) -- maybe if you contact a Moderator, they might be able to do it.
     

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