Hi guys. I have noticed a rather odd «problem» now as I have been using my 550 almost daily for half a year and got time to test it under all kinds of conditions. Sometimes driving the car, there have been this quite unpleasant fuel smell, and sometimes not. I took off the fuel tank cover in the trunk, and there was absolutely no leaks at all that I could see. I supposed the rear facing fuel pump gaskets were leaking, but it was completely dry there. The thing is that I never smell anything like fuel EXCEPT if I drive about 30-70 kph. with one or both windows down!! No smell at idle and no smell at more than 70 kph. even with windows down. How is that really possible..........? This is what I have found out by «examine» the car. 1) The fuel tank is mounted between the cabin and the trunk over the rear axle. To me, it seems like this is a «room» for the tank which is separated from the other compartments of the car. 2) There are two air ducts under this room, actually in the plastic undertrays, one air intake on each side. These looks like they are connected to the «room» where the fuel tank is installed by big vent hoses much like the generator/alternator air hose. So it seems like this room is «ventilated» for some reason. The thing I start wonder about is if there is something wrong with a check valve or something on my car. Every time I open the gas cap to refuel, there is quote a lot of air pressure coming out of the tank filler unit... So my though is that when the car start to move, there is some air flow through the bottom mounted air intakes making the «room» pressurized, which in combination with excessive air pressure inside the tank (which will somehow leak out of the tank itself inside the «room») will then blend with the pressurized air in the «room» which in its turn find its way into the car cabin due to the reduction in air pressure as the windows are opened, and the air coming out of the HVAC vents no longer can «over pressurize» the cabin like normal when the windows are shut. I did one simple test this week. Instead of tightening the gas filler cap, I just screwed it on for one or two turns, making it «water proof» but still able to leak out overpressure inside the gas tank itself... (this is on the outside of the car within the fuel filler area of the body, right under the fuel flap door). Quess what....? Now I can drive with the windows down without sensing any fuel smell when the window are open!! So the big question is... Is it right that there is a real over pressure inside the gas tank? I can fill it up completely with 110 liters of fuel, and there is no leaks at all around the side mounted fuel pumps which would be a logic place to look for leaks. This lead me to think that some overpressure find its way out of the hoses where there are air / fuel vapor in the top area of the tank... Is something blocked or wrong? I have read somewhere that the tank is supposed to be pressurized on cars. But why should it be? I suppose the fuel expands when it gets hot as it return to the tank in the return lines from the engine which is around 100 degrees C. warm. This is one weird problem. Anyone have any experience with this? Thanks, Erik
Might be ...."Quote" Rifledriver said: ↑ I suspect he is speaking of the roll over valves. Most common point of leakage is any of the Ferraris of the period.
I am looking at Eurospares’ parts diagram, and can find no «roll over valves». Where are they located? I am also wondering how the «anti evaporation system» works. It looks like a small vacuum line goes from the intake manifold to the opposite side tank and both tank has a «drain» that goes into a T-fitting and then one hose is going under the car back to the top of the tank.....? Why? Thanks. Erik Image Unavailable, Please Login
I had the exact same issue with my 2001 456M. In my specific case it was the roll over valve. The roll over valve developed hair line cracks. I was hoping this was NOT the issue so I traced through the anti evac diagram you identified. I found no issues. I subsequently had the tank removed and the roll over valve was the issue. The roll over valve has become very difficult to source when I searched 5 years ago. At that time no one had identified an interchange part source / number, which I am sure exists. I was able to source one from FerrParts. ------- Yes, the roll over valve sits on top of the tank.
Thabks a lot for the info! I am looking at the parts diagram, and US/Canadian version has a different tank set-up than the Euro model. I noticed that the US-CAD have also a temperature sensor in the bottom of the tank which the Euro version does not have for some reason! Attached are two pictures showing the two different tanks, and the «valves» as shown as «31» and «50», for the two versions respectively. Are these the valves you were referibg to? There is one for each side. Thanks a lot! Image Unavailable, Please Login Image Unavailable, Please Login
Part 50 is a common culprit, so common a friend of mine recommended a therapeutic replacement when I was working on my tank recently. I opted not to do it, only because I was running out of time before spring driving season! Sent from my iPhone using FerrariChat.com mobile app
Erik- Late US 550s have a fuel cooling system that uses the AC refrigerant to cool the fuel. Warmer here than in Norway. 575Ms did not need it since they do not have a fuel return system.
You are right. I can feel it «misfires» slightly if it is standing still in traffic for over 15-20 minutes. It is as if the fuel is too hot. But I have never experienced any fuel vapour lock so it won’t start. It just runs a tad rough at idle when it is very hot. I guess the engine room temp heat up the fuel rail to over 90 degrees C. so the fuel almost boil... That is the engine room temp around the brake master cylinder when the car is not moving at all and it is about 30 degree C. outside!
Part No. 50 (one screen shot) or No. 21/22 (other screen shot) is what I replaced. I think part no. 31 that you are referencing points to another unrelated part...my eyes are bad and the exploded diagram is small, but I think No. 21 is the left side tank roll over valve and not No. 31. Bottom line - replace both roll over valves; one on each side of the the tank. It takes more time getting the tank out than replacing the parts, so you might as well replace both while your at it. I would also recommend replacing any rubber fuel tubing in that fuel circuit. You probably seen how the rubber under your engine bonnet literally deteriorates; might as well replace fuel line rubber while your at it for the same reasoning. Let me know if you are actually able to purchase these roll over valves from EuroSpares....I had not checked them when I was hunting (bad on me). Hope that helps.
Thanks alot. It is a type error!! i meant 21 of course. It is just refereres to as «valve»... Do I need to take the tank out of the car to replace them?
Are you getting a CEL reading a misfire? I spent a LOT of time hunting down this issue...checking and changing spark plugs, wires, and the coil to no resolve. I also had this checked on by my tech, who spent time trying to hunt this down to no resolve. He eventually said try putting in some fuel injector cleaner every 3 or so tank fill ups. That resolved. No more misfires. No more CELS related to misfires. This may not solve your issue, but it is an inexpensive test. The gasoline in the Bay Area very bad....even with top grade fuel from Shell, Chevron, Mobil and Exxon.
I am not sure if you can / cannot replace rollover valve without removing tank. You might be able to, but at the time I had my tech pull out the entire tank because we were not sure where the problem was....could have been anywhere at that time.
No I have never ever had a Check Engine Light. I runs 100% perfect all the time, but if it is in a hot outside climate and stand at idle for a looong time, it seems to run a bit rough, still running on twelve cylinders, but not perfectly as under normal conditions. I thought I had a real problem, but «got used to it». While running my XK8 in hot South Florida, I learned that the hot fuel will give a rough idle. When I left my car for ten minutes after it was run warm, it started and ran rough for about ten seconds. After that, fine. Every time. So that can happen on the 550 but not when starting. Only when running very hot. I will run a system cleaner additiv every now and then. It might help!
FYI.... FerrParts has a 456 rollover valve listed on ebay: https://www.ebay.com/itm/Ferrari-360-456-550-575-Flow-Valve-Roll-Over-Valve-P-N-180573/133698008154?hash=item1f2105b45a:g:7sUAAOSwquxgU7SY Note the cross model listing for the rollover valve: Ferrari 360,456,550,575 Flow Valve / Roll-Over Valve P/N 180573 That is very important = roll over valves from other Ferrari models will fit your 456...I didn't have that info before.
There is zero data on the fuel control system. It is the FCS light on the center console. I bet the Temp sensor on the bottom of the tank of MY 2000+ tells the FCS to come on or monitor it. Typically FCS light is low freon but it could also be bad temp sensor or maybe the solonoid for the FCs not opening because of the temp sensor???????? Just guessing here.
FBB- Affirmative, I do not have any tech bulletins on the FCS and about the only info I have seen is in the 2001 OM. Sorry about the size, best I could do. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
About CEL, on a Euro car there are only 2 reasons for a CEL, one (if I remember correctly) for the O2 sensors misbehaving, other I forgot. On a US version the CEL even lights when you sneeze I understand. This often leads to miscommunication, when the euro car owner reports "no CEL", where the US car specialist expects one...
As soon as I previously received CELs, I typically pulled over as quickly and safely as possible and plugged in my OBD2 scanner (kept in the car to collect data) and initiate a readout. In my case, almost all CELs had been tied to misfires. I am sure there are other reasons why a CEL is thrown. I took a process of elimination approach: * inspected carbon fuel vapor recovery system for any potential issues * inspected and replaced spark plugs * inspected and replaced ignition wire * replaced all 4 O2 sensors * removed and cleaned the mass air flow sensor * purchased and installed a new spark amplifier No resolution after any of these changes. Misfire driven CELs still showed up on OBD2 scanner. * had my tech go through this CEL issue. He re-reviewed my work, aforementioned. Saw no issues. He finally said try putting in fuel injection fuel treatment; he seemed to recall others having similar issues in our local area. Put fuel injector treatment in tank every 3 to 4 gas fill ups. * put in fuel injection fuel treatment, and I have not had any CELs for the past 2 years subsequently following techs recommendation. I feel like an idiot and should have thought of fuel injector treatment first; the above process of elimination occurred over 2 years and quite of bit of time and money. Reminder to self....try the easiest /low hanging fruit possible solutions first and not last. Don't do what I did. Bottom line - fuel spark sensor is overly touchy and sensitive, especially if engine is under load such as climbing a hill at a certain speed and then stepping on the gas; my guess is the poor gas and or related octane causing either detonation and or dirty injectors impacted under load...but that is just a guess. I noticed the engine runs smoother as well.
Thank you. Words of wisdom! I have run a few small bottle of the silver colored STP full system clean once every year, but not the last year. The only time I get some lights (with my Hyperflow sport catalyzers) is when I am decending down a mountain when the revs are around 2000 while engine braking. Over 2.000 rpm. and no throttle, the engine get zero fuel. (You can see the coolant temp goes all the way down to about 50 degrees C.)... But when the revs are just under 2.000, the engine still get a little bit of fuel even with zero throttle. After about 2-3 minutes like this, my SLOW DOWN red warning comes in the display. If I just rev it a few times of just continue on flat or uphill, the engine works more normally and the warning goes away. This never happened with the OEM catalyzers. On my 456M when running without catalyzers, the light went away when running steady at 180 kph. or more. But was on under that!
Stu- You should probably have your injectors cleaned and resealed. Did that to mine at about 20,000 miles and it really helped. Three were dripping.
Taz, Thanks. Added to list. I will probably do that at the next major since I am at 28k miles. I read/saw the Bradan 456 major thread with leaking injectors. Right now, 456M just a pleasure to drive without any issues.
hey I know old post... which fuel cleaner did you use? I have a few and I'm about to add some this weekend thanks, jay
