Main Fuse ? THe on-off syndrome

[Mark H.]

My '65 was having an on-again-off-again ignition problem (driving down the road fine and then off, just like you pulled the coil wire, then back on again). Now the car won't start at all. The coil is showing 2.5 ohms, and I believe this is too high, but not sure if it is the real problem. Haven't checked the points yet. I was reading a motorcycle magazine and saw a guy that had a very similar problem with his Honda. Turned out to be a main fuse was cracked. Does my '65 have a "main fuse" ? If so, where ? If not, any other thoughts ?

Thanks,
Mark

[Paul Y.]

Re: Main Fuse ? THe on-off syndrome

I would check the back(engine) side of the fuse box. Sometimes the contacts get corroded and don't give a good contact. A good bump will get it in contact again. I would remove both of the wire harness connectors and inspect them. Good hunting. Paul

[Tom L.]

Re: Main Fuse ? THe on-off syndrome

I had a similar problem on my Mustang. Hitting a bump or simply pulling down on the steering column killed the ignition system. Turned out to the the ignition switch itself. A combination of aggressive driving and a stiff suspension broke one of the tabs that held the switch together. Good luck!

[Joel T.]

Re: Main Fuse ? THe on-off syndrome

My '65 was having an on-again-off-again ignition problem (driving down the road fine and then off, just like you pulled the coil wire, then back on again). Now the car won't start at all. The coil is showing 2.5 ohms, and I believe this is too high, but not sure if it is the real problem. Haven't checked the points yet. I was reading a motorcycle magazine and saw a guy that had a very similar problem with his Honda. Turned out to be a main fuse was cracked. Does my '65 have a "main fuse" ? If so, where ? If not, any other thoughts ?

Thanks,
Mark

Mark;

There is no "main fuse" as you mentioned. You might check out the ignition switch as well. If it is original, the innards may be worn which in turn could cause your problem.

Joel

[Grant M.]

Re: Main Fuse ? THe on-off syndrome

Mark,

I had this occur on my 65 as well, and it turned out to be a missing spade lug on one of the firewall connectors (the ones Paul Young refers to at the rear of the fuse box). Simply pushing the faulty connector more firmly against the socket improved the contact enough to re-start the car and drive normally. I subsequently took the time to clean all the contacts with emery cloth and occasionally check that the connector is tight. No problems since in some 21+years...I recently bought a new fuse box assembly and will eventually replace the broken socket.

The only other thing I could think of would be to check connections to the ballast resistor. Years ago I spent a few really cold hours broken down on the highway in a snow storm and awaiting a tow while driving an (army) Dodge Power Wagon. Tirned out all it needed was a ballast resistor (about a $1.89 part)! As the unit transport officer at the time I ordered spare resistors to be carried in the Power Wagon fleet, but I don't recall ever hearing of another failure....

Good luck!

grant

[Mark H.]

Re: Main Fuse ? THe on-off syndrome

Thanks Grant - great info. I'm quite sure the ballast resistor connections are OK, I'll check the resistor itself. Will certainly look into the fuse box. Would love to find out this was the problem !

Mark

[Mark H.]

Re: Main Fuse ? THe on-off syndrome

Thanks Lynn/Joel. Have now heard this from a coupe of NCRS guys. Will check it out tonight. Would be a great (easy) fix.

Mark

[Mark H.]

Re: Main Fuse ? THe on-off syndrome

Thanks Joel/Lynn. Have now heard this from a coupe of NCRS guys. Will check it out tonight. Would be a great (easy) fix.

Mark

[Paul Y.]

Re: Main Fuse ? THe on-off syndrome

Mark, I think that I would use something less aggressive than emery on the tabs. They can be quite fragile. I use a tooth brush with some Twin Etch or Electrical contact cleaner. Don't be afraid to apply some dielectric grease either. You might find that they are just bent or misalighned and can be adjusted. Paul

[Jack H.]

Re: Main Fuse ? THe on-off syndrome

Later era cars had a fusible link as a safeguard against failure(s) in various electrical branch circuits that were NOT switched/fused. That's probably what your friend was talking about...

I've seen the symptoms you describe on cars that were equipped with battery cutoff switches (green knob style) that was the result of the switch's contact surfaces wearing out due to insufficient torque-down force, vibration and electrical arcing eating away at the thin plating.

If your car is equipped with one of these style switches, it's a quick test to remove the switch and see if problem(s) go away. Personally, I use the slightly more expensive knife style of cutoff switch because they have beefier construction and give positive tactile feedback regarding their open/close position.

[Jim T.]

Re: Main Fuse ? THe on-off syndrome

Had a smiliar problem with my 68 back in 1975. Ended up walking home one day, got my tools and went back not knowing what to even look for. Got in the 68 and tried starting it.
It started and drove it home. Lot of trouble shooting later found that the coil was the problem. A terminal stud was turning in the coil. Changed the coil and no more problems.

[Mark H.]

Re: Main Fuse ? THe on-off syndrome

You guys are going to keep me busy this weekend. Thanks for all the "could be's" to look at. I'll let you know how it goes soon.

[Jeff A.]

Re: Main Fuse ? THe on-off syndrome

Here is a quick and simple fix for that old junction box syndrome.
Those little connectors were never made to last 40+ years.

I ran a small wire from my horn relay --all the way around and through the firewall to the little junction "2 post" block by the emergency brake.
That gives you an alternate route for constant 12volts.
No more worry about bad connectors - never had the problem again.

[Mark H.]

Re: Main Fuse ? THe on-off syndrome

Thanks to all that gave their thoughts on this. Will need to continue looking at the problem : I checked it out and have 8-12 V at the coil while turning motor, have spark at the distributor's center "hole" (from coil), and have spark at the spark plug "holes" leaving the distributor.

I've got brand new plug wiresw and plugs, so I have no idea at this point why I can't start the motor (recall it was running fine and just dead while running). Carb is fine. I have no battery "disconnect" switch (to save battery).

Any more thoughts are appreciated

Mark

[Mark F.]

Re: Main Fuse ? THe on-off syndrome

A couple of years ago, my 65 had the same problem. Turns out it was the ballast resistor as someone else identified. Jerry Bramlett helped me solve the problem by simply bypassing the ballast resistor with a couple of alligator leads. When a ballast resistor goes, the metal wire on the back side melts into the ceramic.

Cheers