Issues when filling with gas.

Common problem with the evap system, air can't get out of the tank due to a fault so fuel can't get in.

Check your evap valves, hoses and canister system.
Alden

 

It's often station dependent. I have the same issue with my BMW 335xi

 

Some Exxon stations use a different type of nozzle which has a retractable plastic coil on the end, these stink at delivering gas on all my vehicles. At Shell they have a rubber cover that simply covers the tank spout to stop any spray. These work fine all the time. There is the possibility Evap is having an issue eliminating pressure but try a different pump first.

One time at Exxon as I was pumping gas, it sprayed out a pinhole in the middle of the hose. And the hose had electrical and duct tape. Have never returned there.

 

Did a bunch of people a lot smarter than me show us that shell nitro is the fuel to use?

 

My 348 TS is a non-cat version without the evap system on it and I get the same issue as the OP at certain petrol stations here in the UK.

It seems to Me that in My case, the fuel nozzle goes down into the cars filler tube and sits right by the first bend that takes the pipe forward towards the tank. Because of this, the fuel flow from the pump hits the bend, bounces off the walls of the filler tube, temporarily blocking off the nozzle and so the nozzles automatic cut-off is activated, shutting off the flow.

(BTW, we don't have any rubber or plastic tubes on the end of the nozzles here in the UK)

To counter that, I have to turn the pump handle clockwise until the nozzle is pointing in the same direction as the bend, hold the pump handle up slightly out of the filler opening to lift the nozzle away from the bend, and hold the trigger at half to three quarters of being fully open, in order to slow the fuel flow enough to prevent the fuel washing back and activating the cut-off valve in the pump.

It takes longer to fill the car (which already takes long enough if you're filling from empty due to the size of the tank!), and you do start to wonder if people think you're doing it deliberately just to be noticed filling up a Ferrari, but it's the only way I've found that works. (My car does most things pretty quickly, but filling up is definitely not one of them!)

I'm sure someone will say that they have no problems at all filling up their 348, and that there must be something wrong with My car, but I've had everything checked on the car by a Ferrari specialist who basically said: "I can't find anything wrong anywhere, all your hoses are fine and it's all venting as it should. I think you just need to find a technique with the pumps that works for you"

This isn't the first Italian car that I've owned that was a bit niggly to fill up - On both of My FIAT X1/9's you had to turn the pump handle to face almost completely backwards in order to prevent the pumps fuel cut off valve from triggering, and even then certain stations pumps still put up a good fight!

 

Both I and a highly respected Porsche tech at an area dealership have independently proven that Shell premium fuel is superior not only to other fuels, but to regular Shell gas. I was also told as much by an old friend's husband, who was in the business of mixing fuels. I used to use only Chevron because of BMW's endorsement of Techron, but now I will drive out of my way to buy Shell.

 

When you first remove the gas cap do you hear an extended hissing sound?

 

What Phil said above works for me also. I have even been able to get it to go at full flow but that does vary by station depending on how strong the pumps pressure is.

 

Every time I remove the fuel cap from my 348 it releases a noticeable burst of pressurized air that would easily blow the cap off if my hand weren't there to catch it.

And I too will sometimes have to slow down my fuel filling process to prevent the auto-stop feature from shutting down the flow. It's annoying but it's not nearly as bad as my old Lotus Esprit, so I've never really been bothered by this issue in my 348.

 

Mine varies by station too!

At My local BP station I can only hold the trigger half to two thirds open before it starts cutting off again (It's actually quite surprising seeing just how fast the fuel flows out of the nozzle, even on a reduced trigger pull!)

At the local Esso station - I still have to hold the pump handle the same way but I can have the trigger fully pulled in.

Standing on a petrol forecourt with a slow filling car is okay on a nice warm/hot day, but trust Me, when it's 7°c outside you soon start cursing your beloved car!

 

It is a fault in the evap system and it will get worse, not better. Our cars are "old" and the systems are meant to be serviced.

There is a valve (purge solenoid) that lets air out of the tank as you put fuel in. The air passes thru a filter canister to remove the fuel vapors to decrease air pollution by fuel vapor. If the valve does not open, no air can get out and the gas pump senses the back pressure as a full tank and shuts off.

Different stations will have varying degrees of back pressure to trigger pump shut off, that, and the fact that your air valve may be working some of the time, is why you have better luck at different gas stations.

When you pull the filler out a little you are allowing some air to exit at the filler neck, that is why you can sometimes fill that way, although you may have to go slow.

I would try to diagnose it and repair, it is fairly simple and is probably just one valve or a clogged vapor canister.

You may find yourself doing a one hour fill up at some point in the future, or worse yet, not being able to put fuel in the car at all.

Sample schematic, not Ferrari specific below.
Alden
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I agree with you completely, with two caveats. We frequently see problem in the evap system on cars, so equipped.

However, few cars see adequate service in this area, as "difficult to fill" is often accepted as the norm. No code, no fault sort of mentality. Secondly, pre-smog controlled Ferraris (no charcoal canisters, etc.) too see "difficult to fill" or "must fill slowly" issues. IMO, these are problems related to the fuel filler angle and the way in which the tanks vent back to the filler.

 

Does anyone know where this mysterious valve(s) would be on my 348? I'd love to take a look at it but I have no idea where to look.


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Check the one way roll over valve. It's located up under the left hand wheel well. You will have to remove the top splash guard to get to it. There is a ball bearing inside it that can get gummed up with varnish from the decades of gas fumes passing through, and thus get stuck and not roll freely. If you shake it lightly back and forth you should hear the ball bearing rattle around. If it doesn't rattle EASILY. with light shaking, then its gummed up.

What I am guessing is happening with your fuel fill up is, as the tank is getting filled the air inside the tank is not being allowed to flow past the check valve into the charcoal canister. Pressure builds up inside the tank and the pressure check in the pump handle clicks off from the extra pressure.

That's my best guess.

 

Roll over valve looks like this.
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On your car it does. On most of our cars it's filthy and the yellow zinc on the bracket is oxidizing.

Thanks for the image, Nick!

 

Has nothing to do with the Evap system. The evap system is sealed when the ignition is off and there is no venting; purge solenoids are closed. The evap system never vents to the outside air. It only vents into the intake plenum when the purge solenoids are open. The evap system maintains a zero or positive tank pressure. Excessive pressure may build up in the tank if the 2-way valve is not functioning correctly, but this has nothing to do with filling the tank. When the valve opens it only vents to the charcoal canister where fuel vapors are collected and held until the purge solenoid is opened, allowing the vapors to be ingested into the engine intake.

Tank venting when filling is by a vent tube which runs from the top of the tank to the filler neck, just below where the nozzle restriction is placed. Air then vents out the filler neck, around the fuel nozzle, through the nozzle restriction, which is designed with sufficient clearance around the nozzle to allow the air to exit.

Nozzle shut off is controlled by fuel splashing back over the nozzle tip. This can happen when fuel flow is too fast and/or the filler pipe is convoluted. As has been pointed out, this is not unique to 355s or Ferraris but happens with lots of car.

 

Sure......if you say so.
Alden

 

I happen to understand John's post and agree.

I have a 2008 BMW 335xi as my daily driver. 123k miles. I get gas mostly at 2 stations. One station I don't every have a single issue and the other is a total PITA to fill. The issue is not the car.

 

Thanks! I'll have a look for it in the coming days.

 

I would just like to point out that with a properly operating evac system on a 355 the evac will not vent until the tank pressure exceeds some where between 1/2 and 3/4 psi. Now consider the tank vent as shown in this annotated figure. The vent is open to the atmosphere when the cap is removed. So before the evac system would open the fuel in volume flow would have to exceed the air out volume flow by such an amount as to pressurize the tank to those levels. Given that the air out vent is approximate 25 time as big (cross sectional area) as the evac hoses, even if the tank were pressurized to such levels venting through the evac system would only contribute t 1/26 of the total air flow out of the tank, and that is before considering losses. For fuel to be pushed back up the filler it is simply a matter of attempting to fill the tank faster than air can escape through the air out vent path.

Is it really worth arguing about? Not really.
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Professor John teaches us again - excellent buddy, you are one sharpe guy

 

Don't have to believe me. From the same agcoauto.com site:
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