355 Fuel leakage disappears

Hmmmm I am not aware of any valve that vents raw fuel into the open. Finding where it came from is worth pursuing. If its a 355 isnt there a fuel block that van cause leak issues?

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Klas sshow me in this diagram where the fuel is leaking fromas i do not understandhat you meant

 

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I guess this is the diagram sorry

 

It seems that all the liquid fuel in your charcoal filter was evacuated on the first start. Is it possible to check the tightness of the clamp on the left hand inlet hose? (or is access impossible?)

The Motronics ECU controls the flow of vapours (and I guess liquid fuel) into the intake plenum via the purge valve. The purge valve is rapidly opened and closed with an electrical square wave. This allows the flow of vapour to be regulated (in an appropriate manner). If there is no Check Engine Light, I assume the electrical side of the purge valve is ok.

 

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If we are still talking about 20 in this diagram there is no hose clamp they push in and lock to the intake plenum

 

Ian can you explain how the system pushes liquid fuel up to the plenum from the canister.
Does it pressurise the system??

 

Reading the manual, it appears to be with engine vacuum.

The manual is a little hard to understand, though. It talks about introducing fresh air into the canister when the purge valve is open. The vapour separator between the tank and the canister has 4 pipes on it: One goes to the canister and 3 appear to go to the tank, so I'm not sure where this fresh air is introduced.

https://www.pacificmotors.com/auto-parts-shop/ferrari/ferrari-f355/fuel-system-vapor-seperator-disareator-157977-oem-ferrari-f355-spider-1995/

There is a two-way breather on top of the vapour separator which allows fresh air into the tank in case of a vacuum in the tank, but also allows for slight pressurisation of the tank.

We need a proper schematic for this.

My mistake. I thought the bulge on the end of the hose in the parts manual was a hose clamp. Anyway, they shouldn't leak.

Here's a clear picture of them (I just found) on the Superformance site:

http://www.superformance.co.uk/355/fuel.html (See "Plenum Chamber Spares" / Anti Evaporation Piping" and click on the thumbnail)

 

I guess their may be a clamp from hose to hose. I do not recall seeing it but it obviously has one

 

A dried out hose that has degraded can temporarily seal from re-wetting and swelling. As well, where clamps are involved, the shrinking and swelling from wetting/drying, or large temperature swings, can change the sealing characterisitcs of the joint. It will continue to degrade if drying and degradation was the cause and should be addressed. Likewise a slight snugging of a clamp on aged hoses can help an intermittent leak, but being fuel related, consider changing the item out for new if due to degradation of the rubber.

 

I was just looking at my anti-evaporation system trying to figure out how the hoses were hooked up and found a split hose. In the diagram in post #4 there is a long section of hose numbered "30". Just the small bent section going into item 20 is split. It seems to be a bad design, being forced to make a right angled turn in a small distance.

Has anyone come across this before and what did you do about it? The bent section needs to be more like a right angle section. The sections on my car are held together with ear type stainless steel clamps (which require special crimping tools). I guess I can hacksaw the clamps off and install stainless steel jubilee clips. Just wondering where I can find small, right angled sections of fuel-vapour resistant hose. Something like this would do, but they don't ship to Australia:

https://www.amazon.com/16-Universal-Molded-Fuel-Line/dp/B07G2ZWGRG

The hose dimensions need to be around 8mm inside diameter, 15mm outside diameter. The lengths of a right angle piece would need to be around 35mm and 45mm.

 

When I did my major last July I replaced 99% of the rubber hose's I could see and most of those were totally stuffed where they intercepted or terminated. I know it's frowned upon by some but I just took samples to the local auto store and bought vacuum and fuel hose replacement hose and changed the lot. Not sure if it made a difference but it certainly gave me a sense of security. Especially after hearing about Ferrari eng bay fires. Just a thought.

 

Thanks, Paul. I'll see what they have at Repco or similar. Most stores will have reels of fuel pipes. It's just the L shaped pipe I might have trouble getting my hands on.

 

Ask if they will let you look at the hose hanging up. It's amazing what other cars have on them that are a similar shape then just cut to length.

 

No luck with my local auto store, but they gave me a small piece of flexible 8mm fuel rail hose for free! So, I thought I'd try it.

When I pulled the old hose off, it actually was an L shaped piece of somewhat hardened rubber. I'm not sure if it was original, but it had "A1/TGB/AE1 IMPEROX" written on it.

I had to remove the small cannister (vapour separator) for better access to the "ear type" stainless steel clamps at either end of the L shape. I cut the new fuel hose to the right size with a pair of scissors and fitted it with some small Jubilee hose clamps.

It doesn't look as pretty as the original installation, but there is little compression of the hose in the bend and at least it will stop fuel vapours escaping until I can fit the correct part.

 

Original (cracked) rubber hose

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New hose installation

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Looks like a Ferrari hose I rekon

 

BMW radiator overflow short hose (p/n 17 11 1 712 329, for 8 mm fittings) has a nice 90 deg. bend. It is for coolant but I believe it will be fine in contact with fuel vapours, especially if you get a genuine BMW one as they are very high quality.
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Or get one of these silicone elbows with 8 mm dia. (Australian seller): https://www.ebay.com/itm/ASH-90-DEGREE-SILICONE-HOSE-ELBOW-BEND-RUBBER-COOLANT-RADIATOR-AIR-INTAKE/251553875711?epid=1063164793&hash=item3a91c786ff:m:mmC3UfDVbgovCVdVQWr1VrQ. Preferably blue or red! (they also have it in not so nice black)

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Thanks, Miro. I didn't realise silicone was fuel resistant. I used to have a fuel breather pipe on my Lotus Esprit between the two tanks. I fitted supposedly fuel resistant, but they soon swelled and detached from friction fittings. Clamps are essential.

I'll go for black (It wouldn't match anything on the car). The original hose is quite shiny, so it shouldn't look too out of place.

 

I just saw that the Ebay seller I posted the link to says "Not Recommended For Use With Oil Or Fuel". Probably better to get the BMW one.

 

Why would that be frowned up on? I am sure the car does not mind...

 

Ooops.. Too late.

Looking at one source for the BMW pipe, with shipping and GST, it's getting close to A$100 (and we're still not sure how fuel resistant it is). Ricambi sells the whole original Ferrari pipe (P/N 157979) for U$73.04 (o-rings, clips, postage and GST extra), so I think I'll hold out for that.