355 fuel tank/return valve question

Some times my 355 dosnt start first time but on the second turn of the key. It has not always done it, over the last 2 years it some times does this and then as suddenly as it starts its then fixes its self. So i have put this down to a sticking non-return valve in the fuel pump. I put it down to this becourse if i stop the car and restart it within the min it starts first time. So that tells me that the fuel pressure is not being held by the valve.
So to the question....i have a 1995 model car which has two fuel pumps as opposed to the 1997+ cars which has one.

So are the fuel pumps on both all the same in both models/types??

Also on a twin fuel pump model if one valve has failed then why is the working valve on the other pump not enough to keep up pressure?

I have a spare fuel pump from a single fuel tank and want to locate and change the sticky non-return valve, how can i work out which non-return valve on my twin pump system is not working? Is there a test i can do?
Thanks for any replys

 

Could it be the fuel pressure regulator chaa? There should be one near the fuel rail towards the firewall at the front of the engine? That keeps the fuel pressure in the fuel rail at all times. I wasnt aware that they have they have that setup built into the fuel pumps.

 

That is indeed an option that i never thought about pap I will indeed look at that first.
So if any one can still answer my original question that would be great. Also now another question would be....

How can i tell if its the fuel pressure regulator thats sticking? Is there any tests?
Thanks again PAPs baby

 

Too easy mate. Ive had the same fuel reg issues with alot of other cars. It all depends on how worn the diaphram spring is in the fuel regulator or if it has a pin hole in the rubber diaphram itself. I have diagnosed/fixed cars that when switched off, wouldnt restart on the 1st try after around 10mins. Some would slowly lose fuel pressure overnight. All depends. The easiest way to check and see whats going on is to tee-in a fuel pressure tester/gauge before the fuel rail and then start the car and see what fuel pressure is, then switch the car off. Then we play the waiting game. If its leaking/bypassing badly back to the tank, you will see the gauge slowly dropping away fuel pressure. It may take 2mins, maybe 10mins, and even happens overnight. How long does yours last before it wont restart 1st time chaa? My old Ford used to leak back in around 20mins, before I had to start it on the 2nd attempt. That or turn the ignition on and off a few times to prime the system up. I finally replaced the fuel reg and its great now.

 

You know that does sound like a likely cause of my problem mate i will deffo look at that first. First class responce dude, what a damed shame ya waste ya self on a bloody 348
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Anytime chaa. Let us know how you go brother.
If you had loaned me another $50K when I was Ferrari shopping, then I would be behind the wheel of a 355.

 

Interesting read here chaa. Sounds like your problem mate.

http://www.ferrarichat.com/forum/showthread.php?t=120761

 

Ah no mate thats a hot start problem, Mine starts the same hot or cold. If i start in with in mins of shutting of it will start hot. Mine deffo is a problem with loosing pressure when turned of.
MB: Thought no-doubts bit was very interesting about if the car starts straight away after stoping, mine does. So thanks the thread has helped with a 3rd opinion