Issue with F40 Fuel Gauge

seriously, i never thought or realize the f40 has to 2 tanks. just realized after reading your post.

maybe, it's a faulty fuel gauge then?

 

If its anything like the 308/328 the gauge is fairly random - you should have a reserve light - why not try driving to that once so that you know how the gauge reacts at the low end and at what sort of mileage - there should be about a 3 gallon reserve

 

The F40 has one fuel tank, but two fillers, on either side of the car

 

I think most people may associate the F40 with having 2 tanks, each with its own filler, connected by a transfer line. - Tim
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Correct.

For the USA cars the left hand side tank is more substantial (#143444) and the right side tank is slightly smaller (#143445), but it is common knowledge that there are 2 tanks...

 

They act together however? They are joined with a common connector and the fuel feed to the engine comes from one place? Not like the old Jags where you had a to flip a switch to change tanks.

 

Each has its own fuel pump. Don't know if each pump feeds its own bank or whether they join someplace else. Seems like the engine is two separate 4 cylinders with most everything duplicated. I'm sure the experts on the thread will elaborate on how it really works. - Tim

 

Is there only a single fuel gauge in one of the tanks, or is there one for each tank with the computer averaging them out for the gauge? I wonder if the cars ever have a problem with the connector hose between the tanks getting clogged or pinched. Hmmm... - Tim

 

It sounds more and more like post 3 applies........

 

I'm not trying to doubt you and I don't own one of these fab machines and I accpet there are variations but why then is a reserve shown on the drawing above and a light referred to in at least the Euro 1990 handbook (page H4 # 26) ?

 

Huh? Is that a trick statement? The F40 has a 5.3 gallon reserve, plus a reserve light. ? - Tim
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Tim you've got your work cut out in this thread what with all the clarifications you're having to make to remind owners that there ARE 2 fuel tanks, and that there IS a fuel warning light. Im bracing myself for whats coming next... perhaps they are just testing you.

Good job!

 

Heck, I’ve learned about so many little variations between US and Euro F40s that I can only be sure of what my car has. I’m almost 100% convinced that there’s some F40 out there someplace that’s wired or built differently than what I’ve ever seen, or what the manual says.

Half the fun about these cars is in learning how Ferrari actually made them semi one-offs from time to time as they incorporated changes, or whatever parts they had in the bin at a particular time.

 

True...

 

You're right on the money Tim....despite what some may proclaim, there are no absolutes with handbuilt cars. In some cases, variations to F40's depends on who was working the line that particular day. Case in point, the location of the clutch bleed valve....certain serial numbers have them accessible from the topside of the engine, others are piped to be access from below only. Spent an hour looking for it once based on where the manual said it should be, only to be informed by someone that based on its build date, it was located elsewhere.

Such is the beauty of a hand built

 

Boxer,

In the diagram below of the Euro F40 fuel tank system, part number 21 refers to the fuel gauge from the tank side, and is found on the left side only. This may be the culprit in the form of faulty sending to the fuel gauge instrument. If there is anyway you can check the action of this part, it might help you. Part number is 139703
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This issue brings to attention another interesting difference between USA and Euro F40's, other than the bag tanks found in euro models. The USA fixed tanks have fuel pumps within them. Euro versions have fuel pumps inline separate from the tanks ( #5 in the first pic showing the Euro fuel system) The second pic is the USA fuel system.
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Had exactly the same happen to my (euro) F40 today. Put 25 litres in gauge read 1/4 ish initially then zero with reserve light after 10 mins.
Guess its the sender unit . Did you find a solution to your problem?

 

I am going to double check but I don't think I have a reserve light either......(in fact I am 99.9% sure). Mine is an early 1990 Euro car (originally Italian).

 

The low fuel light comes on in my car when I have almost 10 gallons left. I just figured they wanted to give me PLENTY of warning!?!