General Tech Always Check the Fundamentals

[Mickey Richaud]

Don't know how many times I've given this sage advice to folks who are experiencing electrical issues with their cars: 99% of the time it's a simple fix.

The '73 MGB had been difficult to start for some time now, but with a twist: The starter would turn over fine, but would only start when I'd release the key. Finally it wouldn't start at all, but the ignition light did light up; had someone help push start it and sure enough, it fired right up. Naturally I figured it was the ignition switch that had gone south. After making sure I had continuity from the switch to the starter relay, and from there to the solenoid, I took the old switch out and separated it to clean up the contacts, which were pretty cruddy. Did that, reassembled it, and put it back in the housing in the steering column. Tried it, but nothing - starter didn't even turn over.

So I decided the switch must be bad (or, more likely, I didn't assemble it correctly!) and got another from a friend. Installed it, wired it in and tried it. The ignition light came on, but turning the key to the start position it made no sound at all. Checked the starter relay - it was fine; even put in a spare I had. Now I'm beginning to think it might be the solenoid.

Played around with the connections at the starter switch again and the starter relay and it fired up fine. Thought I must not have secured one of the well enough.

Let it run a while to charge the battery, and then shut it down. Tried to start it again, and no joy - starter turned over fine, but would not run.

Only realized what the problem might have been when I happened to turn on the lights to see how bright they were. The left bank of side and parking lights were out. Checked and found one ground disconnected (no idea how that happened), and they came on, but only briefly. Just for kicks I went to the fuse block and pulled and reinstalled the red wires for the lights; found that they weren't very tight, so cleaned them up and pinched the connectors for a better fit; even the other ones (which didn't seem that tight, either). Tried the lights again, and they came on. Just for kicks I tried to start it once more and it fired up fine. Ran it a while, then shut it down. Tried again and it started - several times. This was yesterday; this morning I went to the garage to see if it would start, and sure enough, it started right up. The only thing I can think is that the wire from the fuse block to the coil must not have been secure and was only intermittently making contact.

Next project is to clean up ALL connections and apply the proper grease to them!

These cars sure can dish up a huge serving of humble pie!

 

[drooartz]

Good reminder, Mickey. Glad you got it figured out in the end.

These cars do have a way of keeping you humble, don't they.

 

[bob67bgt]

Mickey,
The fuse box is not normally a area that would effect the ignition system. Now if its been messed with or different than my 74 well maybe. On my 74 GT the power comes to the fuse box from the key switch with a white wire. Its a double connector and from that connector it branches out to power the coil. (and the green circuit thru the fuse). My guess is cleaning the fuse box will not change the intermittent starting issue. Looking forward to knowing what the fix is! Hollar if I can assist.
Bob

 

[Mickey Richaud]

Mickey,
The fuse box is not normally a area that would effect the ignition system. Now if its been messed with or different than my 74 well maybe. On my 74 GT the power comes to the fuse box from the key switch with a white wire. Its a double connector and from that connector it branches out to power the coil. (and the green circuit thru the fuse). My guess is cleaning the fuse box will not change the intermittent starting issue. Looking forward to knowing what the fix is! Hollar if I can assist.
Bob

That's what I thought as well, but I'm thinking that the issue stemmed from where you said, "...from that connector it branches out to power the coil". I'm wondering if that "branch" is where my issue was. Mine's wired the same way as yours, and I know I have continuity from the ignition switch to the fuse box, and from the ignition switch to the starter relay. Relay's good, replacement switch seems to be good. All I know is that it started when I removed and reinstalled the white wires. (Just went out again and tried it - started right up again.) May have been corrosion inside that double connector that caused an intermittent open circuit?

At any rate, like I said, I plan to do a complete cleanup and greasing of all the connections, especially the starter circuit.

 

[bob67bgt]

I have been hunting a intermittent stumble in my 4 cyl GT. I changed points, condenser, rotor, cap , wires and plugs. Not in that order and even changed the condenser twice. Still there! Next step was to pull the distributor and try again. I changed the point plate since there is a ground wire on it and also changed the low tension wire while in there. I have about 35 miles on the test run and all is ok so far. I have not tried to test the ground wire or the l-t wire yet. I would make up a wire with 2 female ends that can be plugged on the fuse box at the white wire and long enough to go to the hot side of the coil. If you have a problem on the road you can be sure its not at the double connection by running the new wire along with the old one. ( I have a spare spade on the coil and on the fuse box at the white wire.) I would suspect that the electrical part of the key switch is the issue with your car. I wish we lived closer. It would make assisting much easier!
Bob

 

[Mickey Richaud]

Yeah, this virtual reality of the internet can be a blessing and a curse!

My initial thought was a bad ignition switch, but it's done this with two - both original types, not the replacements that are sold today. Anyway, your idea about the spare white coil wire is a good one; will add that to my list.

Still owe you a visit; maybe we can work on that come spring.

Mickey

 

[DrEntropy]

I've even seen a "no start" issue where the rivet holding the spade connector on the input side of the coil had become sloppy, corrosion then made for a poor connection. A "jiggle test" while the engine was running revealed that issue. A soldering gun and a 'blob' of solder fixed it.

 

[Mickey Richaud]

Good info so far - thanks to all.

But with that, let's go back to the initial issue that presented: When I went to start it, it would turn over fine but not fire. It would only fire when the key was released from the "Start" position, and that would occur frequently. That's what led me to thinking it was the starter switch. However, changing the switch didn't seem to fix it.

This may just go down as one of those mysteries...

 

[Jim B.]

I have seen/had the following happen twice. Once on a 1960ish Morris Minor the other on a 61 Mark IX Jag.

The Lucas fuse construction has an issue. The fuse wire is not compatible with the solder used to retain it and form the end cap. Under moist conditions the solder to wire connection will corrode and the fuse will open up BUT it will not appear blown to the eye.
If you look at the very end of the fuse you will see a dark circle surrounding the fuse wire. Checking with a multi meter will show, either an open or high resistance.

I had heard about it from the MM owner and found one on my Jag. If I had not known I would still be there.

 

[bob67bgt]

I also had a coil spade come loose way back when I had my TR4A. Mine always started but would cut out while going down the road and when it made contact again would just about blow the muffler off the car. Fun times!

 

[DrEntropy]

:lol:

Brer Mick; check every connection of the white wire circuit from the iggy switch. There is (or should be) a Lucar double connector at the bundle going down the right side to the rear, two "legs" out, one for the fuel pump, the other for the coil via the fuse box.