308 QV Hot Restart problems after sitting | FerrariChat

308 QV Hot Restart problems after sitting

Discussion in '308/328' started by robo330, May 28, 2016.

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  1. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
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    Karl Robertson
    My 85 308 QV has a Hot Restart problem after sitting for more than 30 minutes or so. The engine has cooled down a bit, but not enough to activate the fuel enrichment. When I turn on the ignition, I cannot hear the fuel pumps running. This only happens after the car has been run, come up to temperature (about 195 degrees), shut down and left to sit for 30 minutes to an hour. Come back, turn on the ignition and crank the starter. No fire! Is there a temporary workaround?
     
  2. Doubleodan

    Doubleodan Rookie

    Nov 5, 2015
    17
    IA
    Full Name:
    Dan
    Same thing happened to mine about 10 years ago and it was the fuel line check valve allowing pressure in the fuel line to bleed down causing very difficult warm restart. I do not remember if the fuel pump could be heard or not.


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  3. miketuason

    miketuason F1 World Champ
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    Feb 24, 2006
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    Mike
    You might have a bad fuel accumulator.
     
  4. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
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    Karl Robertson
    By Fuel Accumulator do you mean the Fuel Distributor unit located in the rear next to the Air Box? I have worked out a temporary work around. Unplugged the Blue Connector which sits just next to and under the Air Filter Box. Now the Fuel Pumps run all the time when I turn the Ignition ON. Before that, if the car had been standing but was still warm, after about 30 - 40 minutes, I guess the fuel pressure had diminished in the lines, but the engine was still warm and the Enrichment device was tricked into NOT serving up fuel to start. Now with the Fuel Pumps working all the time the Ignition is turned on, the car starts even after being left for the 30 - 40 minutes. Question is, Can I be harming anything having the Fuel Pumps working all the time? As long as I don't turn the Ignition and not start the engine...?
     
  5. miketuason

    miketuason F1 World Champ
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    Feb 24, 2006
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    No, this the one right next to the fuel pump. It's job is to hold the fuel pressure after shutting down the engine during or while the engine is hot. Usually located below the lower left fuel tank.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    30°30'40" N 97°35'41" W (Texas)
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    No operational harm, but it is a huge safety risk as if you are in a bad accident and something in the fuel system gets severed/ruptured = fuel at 75 psi will be spraying everywhere (and almost certainly igniting).
     
  7. fly308

    fly308 Karting

    Jun 23, 2007
    183
    Bend, OR
    Full Name:
    Ray
    Had an 83 with the same problem after I bought it, debris in the accumulator.
     
  8. SeattleM5

    SeattleM5 Formula 3
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    Jul 9, 2006
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    Kirkland, Washington
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    Ettore Palazzo
    #8 SeattleM5, May 29, 2016
    Last edited by a moderator: Sep 7, 2017
    Karl, I'm sorry you're having this problem with your QV. This symptom is often the result of the car not holding residual fuel pressure at shut off. As others have mentioned, a compromised fuel accumulator, in particular, a failed internal diaphragm can cause this. I have also seen this in the setting of leaky fuel injectors. I would recommend checking fuel pressures after engine shut off to see if the car is holding fuel pressure. I'm not sure what the specs are for the QV, however for a 328, residual pressure 10 minutes after shut off should be at least 2.7 Bar and remain at 2.6 Bar by 20 minutes. If you find that your residual pressure is not holding I would first check the fuel accumulator. For US versions, remove the hose at the back of the accumulator right after shutting the car off and see if fuel leaks out (see diagram). There should be no fuel leaking from here and if you do see any, it means the internal diaphragm has been compromised. Note that on non US versions there is no hose on the end of the accumulator so if it fails, fuel would leak directly on the ground ahead of left rear wheel. If your accumulator if functioning fine, your injectors can be removed and tested for leaks. I have made a hobby of messing with the CIS systems in these cars and I have a particular interest in fuel injectors. I've ultrasonically cleaned and tested 150+ CIS fuel injectors from the 3x8/mondial/testarossa line and while abnormal spray patterns can be corrected nearly 100% of the time, I have found that injectors with preexisting leaks can be fixed approximately 50% of the time with ultrasonic cleaning. PM me separately if you would like to have your injectors cleaned and tested. Hope this helps and I wish you the best of luck!

    By the way, The first post in the following thread has a link to a nice write up by Carl Rose explaining how to perform fuel pressure checks: http://www.ferrarichat.com/forum/308-328-sponsored-yellow-compass-group/256467-328-kjet-fuel-pressure-checks.html
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  9. Falcon

    Falcon Formula 3

    Aug 19, 2008
    1,302
    New England Region
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    Falcon
    I have a similar situation with my 328. Car starts instantly when cold. I've discovered that my car is flooded. If I hold the excellerater to the floor and let it crank 4 or 5 seconds it starts. I think the injectors are leaking. Give it a try. Hold peddle on the floor. Turn the key and don't be afraid to let it crank a while. Don't give up and lift the peddle. You will end up adding additional fuel. It's a good work around.
     
  10. ClydeM

    ClydeM F1 World Champ
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    My '83 had the issue. There's lots of threads on this with troubleshooting hints.
    Mine was finally found by a dealer to be an intermittent fuel pump issue.
     
  11. SeattleM5

    SeattleM5 Formula 3
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    Ettore Palazzo
    Clyde, do you recall how the dealer discovered the fuel pump abnormality? I would imagine that a fuel pressure check during running would pick up on this issue as well provided the fuel pump was acting up during testing.
     
  12. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
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    Karl Robertson
    Post #8 - Ettore. A new in line valve was added and it seemed to improve slightly, but now the problem is back again. I need to check the leak- down after the fuel accumulator. There is a 16 mm bolt I have been told to undo and see if the fuel leaks out at more than 1 drop every 5 seconds (roughly). Have not done that yet.
     
  13. henrygondorf

    henrygondorf Rookie

    Jan 7, 2015
    19
    NOLA
    disable the cold start fuel injector and try to start
     
  14. ClydeM

    ClydeM F1 World Champ
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    Unfortunately, I don't know. I was just handed > 1K$ bill :(

    But it was worth it as several other shops couldn't find it and it was embarrassing waiting for the car to cool enough to catch.
     
  15. FerrariMech1

    FerrariMech1 Karting

    Dec 14, 2014
    78
    Dayton, OH
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    Michael Wilson
    #15 FerrariMech1, Jun 1, 2016
    Last edited by a moderator: Sep 7, 2017
    The usual, but, unusual method for getting a K Jet car back up and running temporarily is to swap the connectors from the WUR or CPR to the CSV.

    More in depth though... the vapor lock issue is that you are bleeding fuel pressure somewhere in the fuel circuit whether it be from a leaky injector, to a bad accumulator diaphram. Try fixing the cheap components first

    The primary pressure regulator, located on the side of the K Jet Distributor is simply a piston attached to a spring that regulates the amount of fuel going back to the tank in order to regulate control pressure (sounds like what it is?) in order for the car to run rich or lean depending on engine load requirements. There is a little o-ring that effectively seals the primary side of the system from dumping pressure back to the tank when the engine is off. Commonly, on K-Jet equipped cars (at least cars other than Ferrari) 30+ years of this little piston opening and closing can cause damage to this o-ring. This, in effect, can dump your much desired rest pressure and cause hot start issues.

    You can get these o-rings locally for less than $5. Just get a Viton one and you'll be fine
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  16. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
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    Karl Robertson
    Thanks Michael, this last post is a great help! I will pull it out when I get back this evening and see if I can change the O Rings. Sorry to ask this last question, is there a Metric size or some sort of reference number for the 2 O Rings you can share? Thanks again.
     
  17. FerrariMech1

    FerrariMech1 Karting

    Dec 14, 2014
    78
    Dayton, OH
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    Michael Wilson
    I wish I could remember...

    What I ended up doing was buying an assorted set and matched it up that way. If I come across anything, I'll be sure to let you know!
     
  18. chris_columbia

    chris_columbia Formula Junior
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    Feb 5, 2008
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    Try this test: When it is hot and won't start, take the 4 screws off the air filter airbox, and with the key in the run position, push the airflow flap down. If it is the pump check valve or accumulator not working, and allowing air in the lines, you will hear some weird noises as the air is pushed out of the lines. As soon as the air is pushed out of the lines let go of the airflow flap, otherwise you will flood car. Crank car. It should start right up.

    This saved me a few times to get the car started until I fixed the fuel pump check valve. BTW, it usually clogs open from little rust particles in the fuel. I added a pre-filter between the tank and fuel pump to avoid this problem again. The fuel level sending unit in the tank rusts!

    I learned from others here. Riverdriver says that the accumulator is often blamed for this, but in his many years of fixing 3X8, it is extremely rare that it is the problem.
     
  19. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
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    Karl Robertson
    I have also added the pre-filter between the tank and fuel pump. Yes I can get it to start by taking the top off the Air Filter box and pushing the Airflow Flap down. I have been through the "weird noises and then the Fuel Pump being activated. Yes it has also flooded and then I have to wait a few minutes. So I think it could be the primary pressure regulator as Michael has suggested in #15. Any other thoughts?
     
  20. millsj

    millsj Karting

    Oct 17, 2011
    214
    Charleston, SC
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    Joe
  21. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    This is the latest from me on the Hot Start issue: I got a set of Seals from Larry Fletcher of CIS Flow Tech. They are for the Primary Pressure Regulator, refer #15 from Michael Wilson (FerrariMech1). It consists of 1 X Large O Ring 7.0mm, 1 X Rubber Disc (looks like a small O Ring with both sides flattened), and a Copper Crush Washer. Changed the lot, cleaned it all up and started the car. Took a little while as the Fuel filled up and then it ran fine. Took it out for a warm up run, came back, shut it off, waited 10 minutes and it started right up. Shut it off, left it 30 minutes and the same problem as before, no start. Somewhere between 10 minutes and 30 minutes, the fuel pressure leaks down in the system. My next stop is to change the pressure switch in the return line. Fuel Pressure coming to the Fuel Distributor does not seem to be the problem. Fuel in the return part of the circuit seems to leak down when it shouldn't. It's Saturday, and I could not find a Fuel Pressure return switch. So we will try again on Monday. I have organized someone to help me measure the pressure in system, cold and hot. After that I may have to go see a dealer and pay the $1,000 odd!!! (Ref: Clyde McMurdy #14)
     
  22. robo330

    robo330 Formula Junior

    Apr 15, 2014
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    Karl Robertson
    Sorry, I called it the pressure switch, apparently it's called a Frequency Valve made by Bosch.
     
  23. SeattleM5

    SeattleM5 Formula 3
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    Ettore Palazzo
    #23 SeattleM5, Jun 5, 2016
    Last edited by a moderator: Sep 7, 2017
    Karl, unfortunately production of the frequency valve (Bosch part# 0 280 150 300, Ferrari part#121513) fitted to the 308QV/328 is no longer available and can only be sourced from parts cars. A couple of other cars of the era were fitted with the same valve which may help with your search (Porsche in particular), however, they generally have the incorrect length distal choline hose/fuel fitting which will need to be sourced separately. I have one available in the classified section if you end up needing one. This one came from a 328 so it has the correct length hose/banjo fitting: http://www.ferrarichat.com/forum/ferrari-parts-collectibles/523187-3x8-mondial-3-2-frequency-valve.html
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  24. ClydeM

    ClydeM F1 World Champ
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    Nov 4, 2003
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    I should note....I tried most of the fixes suggested here in the archives.
    I visited 3 dealers and an indy who couldn't fix the problem before it happened at a revisit at one of the dealers who was able to diagnose it. $1K was well worth getting rid of that nagging problem.
     
  25. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    Ettore,
    I have sent you a PM. Let me know. Thanks
     

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