main fusible fuse blew

[kned33]

I have a 91 Festiva GL with FI. I left my headlights on accidently and discovered it two plus hours later. Surprisingly the car fired right up! I turned it off open the door and the seat belt didn't retract. I discovered today that the fusible (replacement fusible cartridge fuse had blow). Any ideas on why it would blow?

Thanks for any answers.

[jglutz]

What actual fuse blew?
Where was it located?
What position was the key in when the fuse blew...engine running?
The head lights on and blown fuse may be unrelated.

[kned33]

What actual fuse blew?
Where was it located?
What position was the key in when the fuse blew...engine running?
The head lights on and blown fuse may be unrelated.

The 30 amp (pink) fusible cartridge blew. It is located in the middle of the fusible link block. I only know that after turning off the engine that the automatic seatbelt didn't work. I really thought that kind of odd since the engine was just running. But I reasoned that the battery was more drained than I thought. I tried starting it the next morning and not even a click.

I put the battery charger on. Opened it an hour later and the seatbelt still didn't work. That is when I actually discovered the blown fuse... Haven't had anymore problems since replacing fuse. Still I would like to know what could have cause the fuse to blow.

[nattyphysicist]

I have had this problem many times, has anyone else??

When the battery gets too run down, but not enough to prevent starting, then the charging current draw exceeds the fuse rating and it pops. This stops charging the battery, but the car runs off the alternator. The only way to fix it is to charge the battery with a home charger and replace the fuse.

In the Ford Escort, this same fuse is rated at 80A instead of 20 or 30. My theory is that Ford cheaped out on the cable running from the alternator so they protect it with a low fuse. But does a 30A charging current seem ridiculously high to anyone?

This happened to me last weekend and now both my coil and ignition module do not work. I think the transient from blowing the fuse caused that. This seems like a very bad problem with the Festiva, but it hasn't got much attention here.

Is this the proper diagnosis? Is there a fix?

Nat

[Mike McKown]

I popped a main fuse the other day because of a loose battery cable (on purpose). I've never seen a "regular" car do this but when I hit the key to start, the fuse popped.

I have no idea why but I'd bet the cause of it is related.

[mechanicaldj]

i think the upgrade from Ford calls for a 35 amp fuse

[doylerl]

I've seen some posts on here saying 30-40-30 in the fuse block. I am not sure about the 35, but I know I have heard about the 40 in the middle.

[Pu241]

TSB raised center fuse from 30 to 35.
I personally run 40 in two different cars for 200K miles.
I still have the fuse blow if I leave the lights on and kill the battery.
Best to let it idle (restricting amps to battery) for a while and give the battery a partial charge.
Or if possible trickle charge it over night.
Either way a partially charged battery will not draw maximum amperage and should not blow the fuse.