Fuse on top of the starter blows twice.

[Ernie Vitucci]

Good Evening...One of our Model A Friends has had his fuse blow twice with the car ideling in the garage. Where do you guys suggest I start checking to go from the most likely to the least likely...Thanks in Advance, Ernie in Arizona

[Richard in Anaheim CA]

There is a short somewhere. It could be anywhere but I would checkout the stop light switch 1st
Richard
ANAHEIM CA

[Charlie Stephens]

Check the amp rating of the fuse.

Charlie Stephens

[CT Jack]

Before making suggestions for things to check. Tell us more about what was done before the fuses started failing. Have you been driving the car recently or has it been sitting for a long time? Did you change anything related to the wiring, lighting, add a new device, or replaced the battery? Do have a generator or an alternator and is the voltage 6 or 12?

[Synchro909]

Some of those fuse holders are of extremely poor quality. Tightening the screw when you connect a wire to them can cause the whole terminal to turn and cause a short. They are a non standard accessory and therefore a source of problems - not that all such accessories are problematic but these are, IMHO.

[31deluxe]

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Question on the fuse holders- If the fuse blows, does it affect all of the electrical or just lighting? Does it affect spark and coil function?

[Jim Brierley]

Another idea is to replace the fuse with a circuit breaker. Some are available that merely replace the fuse, others must be hard-wired in place. They will protect the wiring but will be off for a short time then automatically come back on.

[Y-Blockhead]

Originally Posted by 31deluxe

Question on the fuse holders- If the fuse blows, does it affect all of the electrical or just lighting? Does it affect spark and coil function?

The fuse wired in at the starter kills all power except the main power to the starter from the battery. In other words, the starter will still spin the engine but it will not start nor will anything else work.

I wired my Town Sedan so a few essentials bypass that fuse (I use a circuit breaker as Jim suggests) such as my four way flashers for safety. They are fused separately.

[KenBolton]

Kiddo what Synchro said !

[katy]

Originally Posted by Jim Brierley

Another idea is to replace the fuse with a circuit breaker. Some are available that merely replace the fuse, others must be hard-wired in place. They will protect the wiring but will be off for a short time then automatically come back on.

FWIW, There are 2 types of circuit breakers, the kind that Jim mentioned that automatically reset and another kind that must be manually reset.

[HDowse]

I had that problem once and it was the base of the generator cutout grounding out. But as all have said you need to systematically go through all the wiring to find the short.

[Gene F]

I'd try opening up the bail, and opening the end cap (it opens the two halfs twist it in your hands about 1/10th of a turn, and pull - like a tail light bulb). Let it hang for the purposes of test. Hit it with some brakecleen if it is coated with 600W oil. Check the little rubber insulating washer under the tab of the cutout on the generator. Next likely is something touching in the dash panel.

Yes, verify the fuse first.

[Tom Endy]

Attached document is a systematic way of finding the fault that is blowing the fuse on top of the starter. It will isolate it down to one of three areas.

http://www.santaanitaas.org/wp-conte...Quick-easy.pdf

Tom Endy

[henry's 31]

Hi Ernie: I know you heard many suggestions. Besides the fuse holder, the first place I would check is the headlight wiring if you have the original type connection. If he has placed LED taillights make sure the wire is not pinched with the cover.

[Steve_Mack_CT]

Went out to our A a few days after a run & the fuse was blown. I replaced it and the new one immediately blew - luckily I spotted a bit of smoke by the driver's motor mount area and knew immediately what happened. I was tightening float a motor mounts a bit after studying the proper engine height and must have pinched the brake/tail light wires. Putting stock mounts in but my point is even with relatively simple wiring it may take-a little patience.- look for areas wore may rub or punch as has been suggested.

I swear by that little aftermarket fuse - def saved my A and likely our minibarn. Shorts are scary. We nearly lost a restored Packard a week into ownership due to a faulty dome light switch.

Good luck with it!

[mass A man]

This happened to me a year ago on my way to a show. I checked everything "repro" on my truck, which isn't much! Checked the stoplight switch first, nope, found the repro instrument lamp internals were shorting out after two years I had it. I found a good original, restored it and no more shorts.

[ronn]

Good idea to disconnect battery when not using car and also for transporting.

[Ernie Vitucci]

Thanks everyone. The car has had very little use in 20 years. We did replace his fuse holder with a new better quality on from Arizona Model A. We are slowly checking all the wiring for any gaps in isnulation...Next we'll take off the dash modual and check the connections on he Amp Meter and ignition switch and tape the dash behind both. Then check the head lights which are all stock...Will report back in a few days...Ernie

[rich b]

If you replace the fuse with a light bulb; you can use it to diagnose the wiring. If it is on you can disconnect circuits and when the light goes out, you can check thru that circuit and locate the short. If the light is out, you can go around and wiggle the harness, components, and connections and if the light goes on you can check it for the short.

Pretty easy to find if it's a hard short; little tougher if intermittent.

[katy]

Originally Posted by rich b

If you replace the fuse with a light bulb; you can use it to diagnose the wiring. If it is on you can disconnect circuits and when the light goes out, you can check thru that circuit and locate the short. If the light is out, you can go around and wiggle the harness, components, and connections and if the light goes on you can check it for the short.

Pretty easy to find if it's a hard short; little tougher if intermittent.

Good idea.