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Hot (No Start) Issue - Need A New Direction

Discussion in '308/328' started by BrockBenson, Jun 29, 2019.

  1. BrockBenson

    BrockBenson Karting

    Oct 18, 2018
    71
    Australia
    Hello Ferrari Chatters,

    I know this has been covered in many threads, which I've read most but still don't seem to be finding an answer to my hot (no start) issues. Some background, car is a '85 GTSi (US) version. Like many when this issue occurs, the car starts fine from cold, and drives fine. But once up to running temperature and switched off, it will not start. Just cranks over and over, even a little throttle makes no difference. Very annoying.

    As I was ordering some parts for another job, I took the advice that its usually the accumulator and/or fuel pump check valve. So I replaced these while also doing a fuel filter change and replacing some fuel lines down there. Unfortunately it made no difference. Hot start issue remains.

    So I purchased a CIS test kit and did what I should have done first ;) (test the system). Followed a guide I found on FChat which also is similar as the Bosch FI book I have. These were the results:

    ENGINE OFF/IGNITION ON (BALL VLV CLOSED) = 72PSI
    ENGINE OFF/IGNITION ON (BALL VLV OPEN) = 26PSI
    ENGINE ON (WARMING UP) = @6MIN 28PSI / @10MIN 34PSI / @12MIN 48PSI
    ENGINE ON (BALL VLV CLOSED) = 72PSI
    ENGINE OFF/IGNITION OFF (AT OPERATING TEMP) = @1MIN 42PSI / @10MIN 41.5PSI / @20MIN 40PSI)

    I believe this tells me the fuel pump, check valve, accumulator are fine? And that the pressures are within normal operating range. So where to from here? While the engine was hot I disconnected the cold start injector in case it was falsly letting fuel in when hot, but it made no difference (although this was after I had tried cranking the hot engine so could have already flooding the engine?). Could it be leaking injectors? Not sure the above test confirms/denies this?

    Any advise would be very welcome.

    Thanks,

    BB
     
  2. 308 milano

    308 milano F1 Rookie
    Silver Subscribed

    Jan 15, 2007
    3,841
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    Kim
    Are you still running OEM fuse blocks? Just throwing this out there but I had a no start issue with my old 84 GTB. Could walk into the garage and fire up first turn of the key, let it run for 20 minutes shut it off and would not start for a couple of hours. Upgraded to Birdman fuse blocks and never another issue.
     
  3. kcabpilot

    kcabpilot Formula Junior

    Apr 17, 2014
    766
    California SF area
    Full Name:
    Paul
    To begin this may sound weird but you are actually lucky that the condition you are experiencing is a hard fault and not something that's intermittent. Because when it is actually occurring you have the opportunity to diagnose and troubleshoot it. But you need to have an open mind and I say this because you seem to be convinced (so far) that it is a fuel delivery problem even though you have no evidence to prove that. You have already done some good work on the fuel side, maybe try looking at the ignition side as 308 milano suggests and I don't mean just go out and buy new fuse blocks - do some tests.
     
  4. BrockBenson

    BrockBenson Karting

    Oct 18, 2018
    71
    Australia
    Thanks kcabpilot. You are right, I have been focused on the fuel side. Mainly because when I searched "hot start issues" on the forum most were talking about the fuel side being the usual culprit. I suppose I wanted to eliminate fuel first before moving to electrical. Plus I'm more comfortable with mechanical than electrical :).

    Thanks 308 milano. The fuse blocks were swapped out by a previous owner to the Birdman product. So hopefully that eliminates anything in that area.

    Hopefully some other owners who've experienced the same might shine a bit more light on this!

    Cheers, BB
     
    308 milano likes this.
  5. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,147
    San Carlos, CA
    Full Name:
    Mitchell Le
    Your tests confirmed that the fuel pump, check valve, accumulator, and WUR are OK. Now you should check for correct operation of AAV. There is a chance of leaking injectors but I wouldn't go there just yet. Steve Magnusson will come on in a few hours and give you better hints.
     
  6. dinonz308

    dinonz308 Formula Junior
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    Nov 26, 2017
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    Dean
    Mine is experiencing a very similar issue, but mine will start with a decent application of throttle, run rough for 30 seconds, then run fine again - diagnosis was leaking injectors so they're being replaced this week.
     
  7. ferrariowner

    ferrariowner Formula Junior

    Feb 21, 2014
    475
    Mansfield, TX
    Full Name:
    Ron
    Isn't the fuel injection on the QV CIS (Continuous injection system) if so, how can fuel injectors leak? They spray fuel continuously.
    Given the Op's fuel system check results, when the car is hot, check the ignition system (is it getting spark)?

    Good luck.
     
  8. Alex308qv

    Alex308qv Karting

    Jul 1, 2016
    134
    PA
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    Alex
    I had this problem with my '85 after the prior owner had it "serviced" by a shop that did not have an exhaust analyzer. Turns out it was set to run very rich. The reputable shop I use found the CO at a high 9%, adjusted it to spec (0.9-1.1%), and it has started hot and run perfectly since.
     
  9. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    #9 Steve Magnusson, Jun 30, 2019
    Last edited: Jun 30, 2019
    You should certainly confirm/deny if it is an ignition problem as the others have suggested. If it's not ignition, one thing you should do is make the fuel pressure measurement when the problem is happening. Could be possible that the fuel pump is just not running during warm cranking -- just a thought...
    Alternatively, have you tried unplugging the safety switch, turning the key "on", confirming audibly that the fuel pump is running, then cranking the starter during a warm restart?
     
  10. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
    667
    Tulsa, OK
    What was the ambient temp when you took your control pressure measurement?
     
  11. dinonz308

    dinonz308 Formula Junior
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    Nov 26, 2017
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    Dean
    The CIS injectors are intended to be closed until about 3.5 BAR after which they will open. If injectors are dirty or faulty, they will leak under 3 BAR which obviously they're not supposed to do - this can cause a problem of raw fuel in the cylinder, and also means there's no stored fuel pressure in the lines like there's supposed to be.
     
  12. BrockBenson

    BrockBenson Karting

    Oct 18, 2018
    71
    Australia
    Thanks alll for your input. Here are my replies:

    yelcab thanks for confirming what I believe to be correct operation of the fuel pump, check valve, accumulator and WUR. I'll see if i can also test the injectors just to complete the fuel delivery stream before looking elsewhere. My only feedback on injectors would be if they are faulty why don't they not leak all the time, why would this only occur on a hot engine? I'll look into the AVV operation also once I find how to test it!

    thanks alex308qv. I'll keep this in mind if nothing else obvious is found. I can also check and see if a previous owner has removed the plug that allows access to the adjustment in the air meter unit. Normally these do not need adjustment as they are factory set....but you never know the things people do!

    thanks Steve. I'll pull the plugs one at a time and check for spark as a starting point. But I wonder what on the electrical side can be causing this when hot? I technically did the test when the issue was happening. I started the tests cold, but with the gauge connected I left the car idle for a good 30 minutes. Once I finished the tests I switched it off and tried starting it again, and it was a no-go. I haven't tried a hot start with the safety switch disconnected, I'll put that on the list. But as pressure is maintained during the tests I assume the pump is running fine during hot cranking? I did not with engine off, safety switch disconnected, and ignition on - that the system makes a whistling type sound and vibrates. If I put my hand on the injector lines or on the external pressure regulator. Does that sound normal?

    thanks kiwiokie. All the tests were done at about 24C (75F). So not a hot day. Were you thinking vapour lock?

    I'll try getting some more testing done tonight after work. Cheers, BB
     
  13. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Yes, whenever the fuel pump runs (a sort of low hum), the frequency valve will also be vibrating/buzzing. Give a shout if you can determine if it's a no spark or no fuel pump operation during a warm restart not working, and we'll go from there.
     
  14. kcabpilot

    kcabpilot Formula Junior

    Apr 17, 2014
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    California SF area
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    Paul
    A timing light is handy for checking spark. Though you are not looking at timing marks clipping it on each individual plug lead will confirm if it's firing.
     
  15. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
    667
    Tulsa, OK
    No the WUR contains a bi-metallic strip that changes the control pressure as it heats up but is also affected by ambient temperature. The usual control pressure range is quoted at 20C. Based on this chart from the Mondial service manual it looks like your control pressure might be a little low at 24C?

    Image Unavailable, Please Login
     
  16. BrockBenson

    BrockBenson Karting

    Oct 18, 2018
    71
    Australia
    Thanks for the information kiwiokie. That table is handy, I've not seen one before, and its not in the 308 GTSi QV Service Manual I have. The resolution was a bit low so I struggled to see the charts clearly, but I think Fig.33b says 4 Valve USA MY83? Couldn't make out the WUR part number to check if its the same on my 85 QV. But if that chart is right then you are correct pressure is a little low, I had 26psi (1.8 bar) @ 24C and the charts range @ 24C is 35psi (2.4 bar) to 38psi (2.6 bar). Though my 24C reading was ambient temp with engine cold and off, so not sure of the impact of no vacuum on the WUR along with no heat transfer from a running engine on the WUR. Would it of been higher on a running engine with vacuum assist @ 24C? Maybe I need a re-test.

    I also wonder if there is a way to test at several temps to see how linear the results are. Not sure there is an accurate way to monitor WUR temp? or are those charts talking ambient temps? Maybe in my case it starts a little low but gets better with temp and falls within band? I think this might be the case because if you take my full hot reading of 48psi (3.3bar) at unknown temp though, it is with the top part of the band on the chart.

    Going back to my no hot start issue, if we agree control pressure is a little lower than spec, would this be the cause of my no hot start issues and if so why?

    I can feel some more testing coming on .... :)
     
  17. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
    667
    Tulsa, OK
    I had a similar problem on my 911 a few years ago. Would take a few attempts to start, progressively got worse until it would not start when hot without someone manually lifting the air flow sensor. Ended up following instructions online to make the WUR adjustable. Dialed in my control pressure and all is now good. Starts first crank.
     
  18. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
    667
    Tulsa, OK
    The control pressure is what pushes against the plunger in the fuel distributor that determines how much fuel go to the injectors. Low control pressure causes the fuel distributor to flow too much fuel to the injectors for the amount of air.
     

    Attached Files:

  19. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Jan 11, 2001
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    1983 US version 308QV/MondialQV (K-Jet without Lambda) uses a different Warm-Up Regulator FPN 115473 than a 1984-85 US version 308QV/MondialQV (K-Jet with Lambda) FPN 121743. The 121743 WUR senses the atmospheric (barometric) pressure rather than the intake manifold pressure. The 1984-85 US version 308QV/MondialQV uses the same Warm-Up Regulator as the US version 328 which has these characteristics (from the FNA US 328 Tech Specs Publication):
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  20. yelcab

    yelcab F1 Veteran
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    Nov 29, 2001
    9,147
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    Even if the control pressure is a little low, it is unlikely to be the cause of non-starting when hot.
     
  21. Lawrence Coppari

    Lawrence Coppari Formula 3

    Apr 29, 2002
    1,855
    Kingsport, TN
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    Lawrence A. Coppari
    If you do not have a voltage sensor , you don't have to pull the plugs to test if there is spark. You are making extra work for yourself by doing that. Grab any old spark plug that works and attach it to a spark plug lead. Ground the plug to the block. I use jumper cables because one can grab the hex drive on the plug with one. Have someone crank the engine (preferably not in gear with clutch engaged) and look for a spark.
     
  22. FrannyB

    FrannyB Formula Junior

    May 20, 2014
    286
    Arvada, CO
    Have you determined if it is rich or lean when it won't start? Are the plugs wet or dry? This will send you into one of two possible diagnostic paths. I think electrical is a bit of a long shot because of the two independent units and no lights on the dash saying to slow down. Still, I believe there is a connector in the left side of the engine bay (upper) that can become corroded and may be affected by heat. Never a bad idea to clean all those connectors. They were pretty corroded in our car...

    Just a thought...

    Franny
     
  23. kcabpilot

    kcabpilot Formula Junior

    Apr 17, 2014
    766
    California SF area
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    Paul
    Those control pressures shown are cold with WUR unplugged. The next page shows warm pressures with and without vacuum (WUR plugged in after 3 to 5 minutes)
     
  24. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
    667
    Tulsa, OK
    Looks like range at 24C is 2.2bar to 2.75bar so 31.9psi to 39.9psi vs 26psi. 30% low seems more than a little to me and certainly was enough for my 911 to not want to start when warm or hot. Regardless I do not think it is very effective to go troubleshooting CIS with your basic measurements outside of the recommended design parameters.
     
  25. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
    667
    Tulsa, OK
    Or maybe a better way to look at this is the target is the midpoint so 35.9psi and the acceptable range is +/- 11% vs the measured reading which is - 27%.
     

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