Issues when filling with gas.

No one is really arguing about this, it IS a problem with A PART the evac system, not the angle of the dangle on the fuel filler or whether you are holding your mouth right when you are filling the tank. The car did not leave the factory unable to take fuel.

SOMETHING is not letting the tank vent properly and that is shutting off the fuel pump.

I have extensive, hands on experience with this in late model Jags, and replacing one or more components of the evap system ALWAYS fixes the problem and you can fuel normally again.

So, you can keep twisting, pulling the filler out, looking at your watch, going to different stations, only fill on the waning moon and keep a rabbit's foot in your pocket, but sooner or later the problem is going to get worse unless you FIX IT!

From the illustration in your post above, John:

"Expelling gasoline vapor into the atmosphere is not lawful."

".....provides a vent when gasoline is being added.....the fuel vapors flow thru the vent solenoid and into the cannister..."

From the same page:

"Hoses can become blocked by deterioration of the rubber or physical damage."

The site goes on to say that continuing to fill after the pump shuts off (which is what you're are doing here) can cause fuel to flow into the charcoal canister, charcoal can be sucked in the engine, cause engine problems and CEL's.

"When the fuel nozzle starts to cut off, several times when filling the tank, there is a problem. Having the problem corrected before additional damage occurs will often save a great deal of money."

Please read the entire page here: http://www.agcoauto.com/content/news/p2_articleid/242

Chew on that for a while and FIX IT.

I am outta here, been fun guys.
Alden

 

Good article. I'm guessing that when I go to one station with no problems and another with problems, the one with problems has something on the pump filler that is blocking the filler vent and not allowing the tank to vent. Generally I pull the pump handle out of the filter a bit that the issue greatly improves.

Edit: not trying to argue here at all but if all vapors are supposed to go thru the evap system, why is there a vent pipe to the filler at all? Clearly if the car has a vent pipe to the filler, it has a purpose.

 

Here is a related issue/question:

When I first got my car I noticed a strong fuel vapor smell every time I drove the car. I narrowed it down to the driver side rear wheel well area.

Long story short, there is a small hose connected to the fuel filler neck. I reseated the hose and the clamp and the smell was gone.

However, ever since when I go to fill up I get an extended hissing pressure (vacuum?) release when I unscrew the cap. Not a quick whoosh like on any other car but a long hiss.

My guess is that before when the clamp was loose the pressure in the tank was equalized but now that its sealed, whatever valve is supposed to control this is not working.

What do you guys think?

 

What Alden said above is 100% correct about vehicles having problems with the line shown in diagram not properly venting up to the filler neck. Many cars today have some sort of valve in that line as well that can go bad and cause the problem the OP is having. This thread has been concentrating on the vapor line to the canister when what should be reviewed is the vapor line to the filler neck. To the best of my knowledge the 348/355 didn't have any type of valve in this line but it still could be blocked in some way preventing the venting and the resulting "backup" in the main filler neck causing the pump shut off. I know for fact the 996 P cars have the valve I mention and it has been a problem causing almost impossible fill ups if defective.

 

So how does the EVAC/EVAP system cause My 348 filling issues when the car doesn't have one fitted, and all of the pipes, valves etc., that are fitted to the car are found to be in perfect working order?

(Not My words but the words of a Ferrari specialist who worked on the car for Me)

And you do not think fuel wash-back from the nozzle can cause that?

So how do I fix something that's not fitted to the car?

In your own words: "Chew on that for a while and" tell Me how to "FIX IT." on a car that doesn't have it fitted from the factory!

Please don't leave! - I need your help to FIX the EVAP system on My 348 that it has never had since it left the factory back in 1990!

 

I think this just confirmed what JohnK had posted with regard to the filler neck vent tube...

 

Ok, Phil, your sarcasm sucked me back in, thanks.

Your car still has a way to vent air from the tank, it may not be an EVAP system in the classic sense of the word but something that's supposed to let air out of the tank when fuel is introduced is not working properly. And, it cannot be an open tube without a valve, or circular baffle of some kind or fuel would come out when the tank is full or under hard cornering.

Valves, baffles and tubes, for that matter, can and do clog or stop working.

People here are trying to say that the fuel filling system in their car is working properly and that is clearly not true, regardless of what your mechanic may say.

But, in the end, if you think your car is fine and your mechanic says it is fine and you like spending a lot of time at the pump, then carry on.

Just sayin'....
Alden

 

Guys, before I start getting hate mail, understand that this thread started out saying check the roll over valve; check the purge solenoid; check the 2-way valve, and that the problem was with the evac system. The point is, it is not a evac problem. Could the vent hose be clogged? Yes. But if it is, it's still an issue with fuel splash back due to excessing filling rate or just because of the position of the nozzle in the filler tube. Recall, older cars didn't have evap systems or vent hoses. Air came out the filler as fuel went in.

Could there be problems with the evac system? Yes. Would they cause this on a 355? No.

I'm not picking on anyone here, just trying to prevent someone from checking a lot of stuff that isn't relevant.

 

My fuel fill up speed is not the best Ive seen but I don't consider it to be faulty. Just a design issue. I think you just have to accept this for what it is. The vapour return hose to the filler neck is clear so it can't be that unless its too small a bore to deal with the displaced air when trying to fill fast. Unlikely but possible. I normally use the same fuel station too. The car also suffers from a pressurised tank which has only showed itself in the last year or so. I have always put that down to a fault in the EVAP system which I will be looking at in more detail in the near future. The roll over valve appears to be working correctly on inspection. The excessive pressure is positive so rushes out rather than in.
The important thing here is the fill rate has not changed since the pressure issue arose so I find it hard to relate the two complaints. As John mentioned, the amount of air displaced when filling would never pass quickly through the EVAP system plus from what I read in the workshop manual the solenoid valves need to be energised to allow fumes to pass, dependant on the various operating conditions of the engine. Not very specific. They are controlled by the ECUs so would need power to those when filling . There is only one way for the air to go when filling and thats out of the neck. 50 litres in means a lot of air out. It has to go somewhere plus if you can smell it its coming out to atmosphere. As I've said, there is no difference on fill with or without the pressure issue. Just my real world thoughts and observations.

 

"Expelling gasoline vapor into the atmosphere is not lawful." (in the US anyway)

I edited your text above to show all the faults and problems you listed in your post, that is a lot of stuff wrong to call it "normal."

Everyone is falling all over themselves to call these issues idiosyncrasies of our Ferraris.

I will give you poor A/C function, difficult ingress and egress, rear visibility issues, and expensive parts as part of the Ferrari mystique, but the faults we are discussing in this thread did not come from the factory and can be fixed, I have fixed enough "unfixable" fuel filler problems on other cars to know it can be done.

And no one is chiming in here to say that there are 1200 identical cars that came out of Maranello of the same year and model that will not take fuel normally.

I know, the pumps are slower in Italy, right? ;-)

Can't we discuss engine oil preference or something less controversial?
Alden

 

Alden,

I think the folks here are having an open discussion and you are getting upset which I don't understand. I posted earlier - what is the purpose of the filler vent tube if "Expelling gasoline vapor into the atmosphere is not lawful" ?

I'm not being a smart ass - it's a legitimate question I'm asking you.

 

Pressure build up is not a fault. As I posted initially, and as can be found in the work shop manual, the 2-way valve which vents the tank to the charcoal vapor collector WHEN THE CAP IS ON THE TANK, allow the pressure inside the tank to build up to about 1/2 to 3/4 psi before opening. Now much pressure builds up and when depends on several factors including how much fuel is in the thank, and ambient temperature variations.

These are not things unique to Ferrari.

As far as "Expelling gasoline vapor into the atmosphere is not lawful." That is a statement taken out of context. Some may recall gas station which had plastic bellows overt the fuel nozzle which had to be compressed against the filler neck. That was a system which was used to collect the vapors expelled from the tank during filling. They are no longer required in most states as it was ultimately not considered a problem.

[edit] Pressure build up is not a fault...unless it exceed that level at which the 2-way valve should open. (Just to be clear. )
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I guess I must be lying then. Im out.

 

It can also have to do with the Reid Vapor Pressure (RVP) rating of the fuel and the local station adherence to RVP requirements. There is also an allowed seasonal variation in the RVP in many states. In summer months, the RVP allowance is lower and if you live where its warmer and have ethanol "enhanced" fuel without the summer requirement for a lower RVP... you can get a much higher vapor level which can trip the pump shutoff as you will get higher vapor levels during fueling as you slosh the fuel. Since the summer cut over is June 1st, you might just be fighting the increased vapor allowance especially with added ethanol. That is why you can see this issue in many cars that aren't Ferrari's.

You should make sure the vent line from the tank to the filler neck is not blocked... and if its not blocked...

Avoid any gas station where you get frequent tripping on the auto shutoff. It could just be the fuel.

 

yesterday i unscrewed my cap quickly while the pressure was releasing. the cap practically flew off the neck. seems like more than .50-.75 psi. I've seen several suggestions to check for clogs on the vent line from neck to tank.

any other suggestions?

 

If you calculate the total pressure on a 3" cap, you get between 3.5 and 5.3 pounds, higher than you might have thought. That's enough to make it feel like it could slip out of your hands if you weren't careful or expecting it. The pressure will be highest on a warm day when the tank is near empty so around 5 pounds or so is about what I feel when I refill on a hot summer day and I believe my system is functioning normally.

 

Yep. Force = Pressure x area.

 

This is the pump nozzle that always works best...

 

Ok, officially now the cute girls pumping gas thread:
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Nice

 

This thread has suddenly taken a turn for the better.