Starting problem

[John Larkin]

I stalled my '73 Sprint at a junction yesterday, and it would not re-start. The starter motor worked just fine --- but there was no ignition.

Two hours* checking this morning and it transpires that the starter solenoid delivers 12V to the coil when the ignition switch is in the ignition position, but nothing when in the starter position. The starter solenoid does not have a manual starter button as on my S3 Elan, so it may not be the original unit.

Any suggestions apart from a new starter solenoid?

*My wife tells me that I show more compassion, patience and understanding to my cars than to any human being. Any psychiatrists reading this?

John Larkin

[john.p.clegg]

Something doesn't sound right there "the starter soleniod delivers power to the coil"?
Do you mean the starter switch?

John

[John Larkin]

You're right. I meant to say ignition switch (the car's not the only one with wiring problems it seems).

I realised my mistake just after I posted the topic but I could not get back onto the website till now.

Investigative surgery on ignition switch now in hand.

[john.p.clegg]

Sounds like a new switch required as 12v is given to the coil from one connection on the switch in both the run and start position by a "bridge" in the switch....
Best of luck

John

[john.p.clegg]

Just forgot-you may have a ballast resistor in the circuit,in which case this may be the culprit

John

[Frank Howard]

The ignition switch "...delivers 12V to the coil when the ignition switch is in the ignition position, but nothing when in the starter position."

John, your ballast resistor would be suspect if the opposite were true. That is if the ignition switch delivered 12V to the coil when the ignition switch was in the starter position (III), but nothing when in the ignition position (II).

I suggest you go to another topic in this section (Elan) called "More Electrical Gremlins". Gary from Miami has the opposite problem in that his car will not stop. Perhaps the two of you should get together!

Gary has photographed the back of his ignition switch and that section contains information that you will find relevant.

One other thing. Are you using a Gustafson Super Starter, or are you using the original Lucas starter? Good luck.

Frank Howard
'71 S4 SE
Minneapolis

[John Larkin]

The car still will not start through the loom (but will on jury-rigged wiring).

I removed the ignition switch yesterday. The wiring does not match the workshop manual (fewer wires, some different colours), although they look original. There was one broken brown wire connected to one of the ignition feed terminals with no insulating shroud on its spade connector, and I suspect it is not part of the original wiring.

There should have been two white wires instead of just one on these two ignition feed terminals --- one feeding one of the two fuses, and the other feeding the ignition coil via the tachometer. Instead the single white wire goes to a four-way bullet connector from which a feed goes to the tachometer and connects to one of three connectors on a recessed brown plastic thingy (voltage stabiliser??) at the rear of the tacho. Another white wire leaves that same brown plastic thing and goes to the coil, and it has seriously overheated --- it melted its insulating shroud. The melted plastic cemented the electrical connections together.

My wiring diagram shows four green wires connecting to the voltage stabiliser in the tachometer. I have found three wires --- two white and one green --- connected to the recessed brown plastic thing.

Is this the voltage stabiliser? Why does the feed to the ignition coil come from it? What happen when it fails? Any ideas why the output to the ignition coil should overheat?

I have cut two fingers on my left hand, and badly grazed my right wrist investigating this problem, and I'm feeling very sorry for myself.

Can some enlightened soul please help?

John Larkin

[john.p.clegg]

John
When the voltage stabiliser fails,the readings on your fuel,oil pressure and engine temp. are affected,either no reading or increasing/decreasing with engine revs (increased voltage),remember they are dampened and thus slow to move...

Best of luck...

John

[Frank Howard]

"There should have been two white wires instead of just one on these two ignition feed terminals --- one feeding one of the two fuses, and the other feeding the ignition coil via the tachometer."

John, why do you say that? If that were true, then the accessories would function only when the key was in position II or III and you don't want anything except the starter and the ignition working when the key is in position III.

"...a feed goes to the tachometer and connects to one of three connectors on a recessed brown plastic thingy (voltage stabiliser??) at the rear of the tacho."

The "recessed brown plastic thingy" is an insulated board that holds the tach connections. It's part of the tach, not the voltage stabilizer.

"Another white wire leaves that same brown plastic thing and goes to the coil..."

That is the same as the white wire going in. The two connections are on either end of a short white wire inside the tach. The wire inside the tach loops around a magnetic pickup and exits right next to where it goes in. One connection is male and the other is female. That way, if you want to run you car while the tach is being repaired, you just connect the two white wires to each other instead of running them through the tach.

"...and it has seriously overheated --- it melted its insulating shroud. The melted plastic cemented the electrical connections together."

OK, now we're getting somewhere. You've got a dead short in the wire that goes from the tach to the coil. The short may be the result of the connection at the coil touching ground, or it may be the result of the wire itself touching ground between the tach and the coil. I'm surprised that the white wire from the bullet connection to the tach is OK. I can just about guarantee that the little white wire that I was talking about that is in the tach is melted also. You'll have to remove the tach and have a look. A new one can be fabricated if you can salvage the male and female connections. Meanwhile, as I suggested above, connect the two white wires to each other, bypassing the tach while you attempt to solve this problem.

"My wiring diagram shows four green wires connecting to the voltage stabiliser in the tachometer."

The voltage stabilizer in not in the tachometer. It is mounted on the rear of the tach or the rear of the speedometer, I can't remember which. (I have since moved mine to another location.)

"I have found three wires --- two white and one green --- connected to the recessed brown plastic thing. Is this the voltage stabiliser?"

Again, the "recessed brown plastic thing" is the circuit board that holds the tach connections. It's part of the tach, not the voltage stabilizer. We've already been over the two white wires. The green wire is 12V coming in to power the tach.

"Why does the feed to the ignition coil come from it?"

I think I've already gone over that.

"What happen when it fails?"

No power to the coil.

"Any ideas why the output to the ignition coil should overheat?"

Dead short somewhere between the ignition switch and the coil.

Have you taken my suggestion and looked at the "Gremlin" post? Good luck.

Frank Howard
'71 S4 SE
Minnesota

[John Larkin]

Thanks Frank for the comprehensive reply. I appreciate the time you took writing it.

At this point I have I have boiled the facts down to this:-

The white wire with the melted insulator is the feed to the coil but it shows a loss of continuity between the tacho and the coil. I understand that in the Sprint this wire feeds the coil via an anti-theft switch (which I am having difficulty finding, but I'll continue searching for it this evening). So I suspect that I have a faulty anti-theft switch, broken connections, or a short on the coil feed.

The loop of wire inside the tacho is showing electrical continuity, so may be OK. How do I open the tacho? Must I remove the chrome bezel?

The Lotus wiring diagram for the Elan deserves a prize as a work of fiction.

John Larkin

[types26/36]

I understand that in the Sprint this wire feeds the coil via an anti-theft switch (which I am having difficulty finding

John,
The anti theft switch is located at the right side of the glove box, it is quite small and can be quite easily missed with a quick glance.
(p.s. dont tell anyone about this switch )

[John Larkin]

Today at lunchtime I ran a temporary cable from the terminal on the tachometer to the coil, and I the car started and ran without a problem. The tachometer works just fine. So the culprit was the low tension "output" from the tacho --- the one with the melted insulating shroud. I'll have to trace the old cable and see what the problem was, as there must be an electrical discontinuity somewhere.

I'm still trying to reconcile the actual wiring with the diagram in the manual, although I suspect that this may prove to be a futile occupation. The Lotus wiring diagram seems to be more of a draft design intent instead of an as-installed drawing.

I appreciate very much the support and advice I have received on this forum.

Thanks again!

John Larkin

[Frank Howard]

"So I suspect that I have a faulty anti-theft switch, broken connections, or a short on the coil feed."

John, you are definitely on the right track.

"The loop of wire inside the tacho is showing electrical continuity, so may be OK."

It's OK as long as the insulation is still on the wire.

"How do I open the tacho? Must I remove the chrome bezel?"

Yes, you must remove the chrome bezel but only after removing the tach from the dash board first. There is a rubber gasket just behind the bezel. Slide this off the back of the tach. You'll notice that the bezel has several tabs that wrap around the back of the flange that is the front of the can. This flange has corresponding notches in it. Grab the bezel and rotate it until the tabs line up with the notches and the bezel will come off with the glass. Supporting the glass is a ring that must be pried out. Then undo the two screws holding the guts to the back of the can and they will fall out into your other hand hopefully. Good luck.

Frank Howard
'71 S4 SE
Minnesota