308 - Fuse Question

Sounds like a couple of fuses may have got swapped.

It's fairly common for the water pump fuse connector to get overheated, either due to poor connections to the fuse, or a failing water pump. That's what the brown discoloration is.

The fuse blocks have a history of poor connections/overheating & have to be watched carefully. The contact design is fairly marginal.

A lot have people have been buying Birdman's retrofit fuse blocks that take std fuses. They don't look the same, but fit the same & take std automotive fuses instead of the torpedo shaped fuses.

I recommend searching for 'fuse block' and deciding what you want to do.
Search both the current fchat & the 'old ferrarichat'.

 

I do recall a discepancy on my old 78 308 GTS, between what was shown in the owners manual, and for what was indicated on the fusebox cover. I think it was an 8A vs 16A, too, and it might have been for the parking lights.

8A should be sufficient for the parking light circuit. I believe on my 328, this circuit uses a 10A fuse.

In general, you should not use a higher amp fuse than the designers selected. They know what is a normal current draw for your circuit. Try going back down to what was originally called for. If you start blowing fuses, you might have a small short somewhere that the owner got around by putting in a higher amp fuse (not a good idea). Other times, you just don't have the right fuse so it's one of those "any will do for now" things.

--Mike

 

verell I DID NOT KNOW THAT 308 USE A FUSE TO RUN THE WATER PUMP. THIS IS A FRIST ONE FOR ME.

 

I think we mean "fuel" pump. Looks like water, anyway.

 

In the parking light circuit I would go with the 8 amp, since that's what is printed on the fuseblock covers. If it blows for no apparent reason, you could try going a little higher. In general you should try to limit the values to something reasonable. The whole point is that you want the fuse to blow if something is wrong.

Birdman

 

I am having a similar problem with my 83 Mondial QV. The Fuel Pump fuse gets very very hot, the plastic fuse body distorts with the heat. Contacts are brown due the excessive heat. My car will generally stop at least once in an hour of driving as the contacts generate so much heat they part their ways.

The temp fix is to replace the fuse every once in a while and burn ones fingers squeezing the contacts back together. It then starts instantly.

What bothers me is so far car has only stopped at traffic lights (yes it is funny for passers-by to see a Ferrari with the bonnet up), however if it did it on the motorway/highway then that is another thing.

I have purchased myself a fuse box with two spade connector type fuses. I intend to bypass the fuel pump fuse and possibly the a/c.

I also need a wiring diagram, I think Ferrari_tech_UK on this forum has them for sale.

 

Malc

There is a normally a wiring diagram in the owners handbooks.

Steve

 

Is there, can't say I have noticed it but will look this evening. Cheers Steve.

In fact there are soft copies on www.owners.ferrari.com I think, I will look

 

Ferrari UK has a dedicated book with a larger schematic than what is supplied in the 308QV owners manual. Cost about $60 as i recall, though other sources ask $100 for it.

 

Take your owner's manual to a copy shop and have them blow it up to an 11x17" size. Much easier to read. I had several copies done. Then I just use a hi-liter for the circuit I'm trying to follow. Once the copy is too messy, just recycle it and start with a new one.

Regards, Kerry

 

It doesn't sound like the problem is the fuse. You've got a problem somewhere else in that circuit. Before you start tearing things apart, grab you multimeter and check all of the parts of the circuit and the pump itself. You should not be generating that much heat at the fuse. And check all the connections, especially at the fuse box, to make sure they are tight, that they are not corroded, and that they are not shorting out on you.

 

I should mention, this is not the first time I have had issue see http://www.ferrarichat.com/forum/showthread.php?t=34979

There has been some repairs done previously. I am inquiring as I type about a permanent fix. I would like to replace the whole fuse box, but not enuf money in the pot for that at present as I have other needs. The fuel pump was checked last year and is OK. A fix was made to the rear of the fuse box panel, exactly what was done I am not 100% certain.

PS sorry I seem to have temporarily hijacked this thread.

I believe the best fix for this old fuse box is a replacement, but make sure you don't get a direct replacement i.e bullet type fuses, as I imagine the same will happen again.

 

These symptoms are consistent with a fuel pump that's starting to fail. First symptom is a significant increase in the current drawn by the pump to around 12A - 14A. Recommend measuring the current drawn by the pump to see if this is the case. You can pull the fuse & connect a 20A or higher ammeter across the fuseholder contacts.

BTW, one very hot day last summer I too lost a fuel pump fuse at a stop light! The load on a CIS pump seems to increase when the engine is idling & thus not using gas. I speculate that is because the resistance to fuel flow is higher thru the regulator's bypass back to the tank than the flow resistance thru the CIS.
However, it's a known problem for the fuse block metal contacts to get hot enough so that they loose tension enough so that the fuse keeps overheating. Only fix is to either replace the fuse block, or else use an auxiliary fuse the way you're suggesting.

One thing that can help is to use one of the glass bodied torpedo fuses instead of the ceramic ones. The glass bodied fuses have large metal tips like std 3AG fuses, thus dissipate heat better. Also, the metal doesn't tarnish up & degrade the fuse-fuseholder connection the way the tin on the ceramic bodied fuses does.

Hmm, first for me too! Early Alzheimers I guess (DUH).

 

Not with Mondials. The schematic is too complicated. There is a seperate publication for it and they break it up into like 17 pages!

The early Mondial fuseboxes are as bad as 308s because of those nasty conical-ended fuses with not enough contact area. The small contact area causes resistance which causes heat, which melts things. Then the fusebox gets flaky. Same thing as in the 308 fusebox, except the fusebox is much more complicated.

My Mondial QV has the blade-type fusebox from a Mondial 3.2. The previous owner got tired of the electrical issues and upgraded it. He told me it cost $1,000! (yikes!) I have never had any electrical issues with it. <crossing fingers, knocking wood>

Birdman

 

I am assuming this was part of the test done. I will find out, thanks

Which possibly means that as I am moving that the problem is certainly less likely to happen.

Not aware of the ceramic bodied torpedo/bullet fuses here in the UK. Anybody?
The existing fuse looks like one of the attached. The body is plastic I am sure?
Image Unavailable, Please Login

 

BUSS catalog calls the torpedo fues bodies 'ceramic', however, I've come across some melted ones that sure behaved like plastic.

Anyway, once in a while you can find glass bodied torpedo fuses.

Last year I called BUSS about them & they said that you can get either the glass or the ceramic/plastic style depending on who gave them a good price at the time they boxed them up.

Called LittleFuse, they never heard of the glass ones.

I then called all the local auto parts stores & talked them into going thru their bins & getting me a supply of the glass ones. Got enough to change out all my ceramic/plastic fuses with glass & a low supply of spares.

Good luck,

 

Thanks Verell I will look into it.