Lotus Elan

Ignition problems, another no sparker! Advice please FIXED

PostPost by: RichardS » Thu Jul 22, 2021 5:11 pm

Problems started last week. My Elan Sprint normally starts first time but took a little longer than usual to fire. Then started cutting out after engine warmed up, fortunately in the drive rather than out and about. Engine stopped dead.
Engine turning over fine but not firing now.

I established there was no spark at the plugs, but good regular spark from the coil HT lead so presumed faulty distributor cap. Have replaced the rotor arm and new distributor cap and leads, and plugs, but still the same issue. No spark at plugs but fine at coil output.

I have Aldon ignitor electronic ignition, which seems the only part left to suspect. But if I am getting a good regular spark from the coil doesn’t that suggest the Aldon is triggering ok? Can’t work out why, if distributor is getting volts from the coil then volts not being transmitted to the plugs.

Engine earth is fine.

I am puzzled and wonder if anyone can suggest where to go next

Thanks

Richard
Last edited by RichardS on Thu Aug 05, 2021 2:44 pm, edited 1 time in total.
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PostPost by: Billmack » Thu Jul 22, 2021 5:18 pm

If you put in a black rotor arm, try a red one. The black ones are often defective and short to ground thru the cam
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PostPost by: RichardS » Thu Jul 22, 2021 6:05 pm

I’ve fitted a red one!
So it’s not the rotor arm…
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PostPost by: mark030358 » Thu Jul 22, 2021 6:07 pm

I have a spare set of leads, cap, rotor arm and electronic ignition if you want to borrow them? And a spare coil too.

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PostPost by: RichardS » Thu Jul 22, 2021 6:30 pm

Thanks Mark, I might take you up on that kind offer!
Coil is generating a spark from its HT lead and ignition generating a regular spark so it seems it has to be a problem in the cap or distributor. Suppose I might have been unlucky with the new cap but I forked out for the Magnecor set so think unlikely
Just chatted to my brother in law who is a retired mechanic and he is baffled.
I recently posted I never have electrical problems with the Elan so serves me right!
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PostPost by: EPA » Thu Jul 22, 2021 7:08 pm

Check that the blade of the rotor arm aligned with the posts in the distributor cap when the ignition is firing as the distributor may have moved and the spark is being generated when the rotor arm is in the wrong place
Best of luck
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PostPost by: RichardS » Thu Jul 22, 2021 7:49 pm

EPA wrote:Check that the blade of the rotor arm aligned with the posts in the distributor cap when the ignition is firing as the distributor may have moved and the spark is being generated when the rotor arm is in the wrong place
Best of luck
Ed


Thanks Ed, that sounds logical and may be the answer. Hadn’t thought of that but would explain the missing spark.
What’s the best way of checking this?
Richard
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PostPost by: HCA » Thu Jul 22, 2021 8:06 pm

assuming the dist cap is not cracked, the centre carbon is in place, the rotor is good, the posts are good, the cables are good and placed in correct firing orders and the plugs are good, then a spark from the coil should fire a spark at the plugs.

You say there is no spark at the plugs - you have had all the plugs out, earthed and no spark whatsoever, yes?

However, you say there has been a lead up to all this and that it did not happen suddenly. Coils can appear to give out a spark on the bench but break down when it matters - usually after warming up. Have you measured the windings? You do not say if the coil is with or without ballast resistor. Readings are different for each - check them out on the internet for whatever coil you have.
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PostPost by: EPA » Thu Jul 22, 2021 8:23 pm

RichardS wrote:
EPA wrote:Check that the blade of the rotor arm aligned with the posts in the distributor cap when the ignition is firing as the distributor may have moved and the spark is being generated when the rotor arm is in the wrong place
Best of luck
Ed


Thanks Ed, that sounds logical and may be the answer. Hadn’t thought of that but would explain the missing spark.
What’s the best way of checking this?
Richard

I would set cylinder 1 on the firing stroke and at the the timing mark and the rotor arm should be aligned with the post for cylinder 1
As has been said if the cap/leads are good and a spark is being generated then it should be distributed out.
How are you testing the spark from the coil?
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PostPost by: RichardS » Thu Jul 22, 2021 8:28 pm

Thanks Hal
Cap/leads/rotor arm all replaced
Definitely no spark at plug end.
Even when intermittent I was always getting a spark from the coil HT lead whether cold or hot.
I will investigate Ed’s suggestion that the distributor might have moved so the volts are not getting from the rotor arm to the posts
Richard
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PostPost by: RichardS » Thu Jul 22, 2021 8:34 pm

Thanks Ed, that sounds logical and may be the answer. Hadn’t thought of that but would explain the missing spark.
What’s the best way of checking this?
Richard[/quote]
I would set cylinder 1 on the firing stroke and at the the timing mark and the rotor arm should be aligned with the post for cylinder 1
As has been said if the cap/leads are good and a spark is being generated then it should be distributed out.
How are you testing the spark from the coil?
Ed[/quote]

Testing spark by earthing distributor end of coil lead to ground, and always getting a regular spark when turning engine over
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PostPost by: EPA » Thu Jul 22, 2021 9:21 pm

I think it highly unlikely that the relationship between the rotor arm to distributor cap is incorrect as they are located in a way to prevent this (though I once had this happen but can’t remember why). It’s more likely that the spark is tracking to earth somewhere and you should look for tracking marks on the distributor cap and the rotor arm.
Sometimes it’s worth watching in darker conditions when it’s easier to see any unwanted sparking.
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PostPost by: SENC » Fri Jul 23, 2021 12:28 am

I'm with Ed, and would check the inside of both distributor caps closely for signs of arcing within. I had similar symptoms, though with a traditional distributor - finally found a small trace in an odd place, and realized the connection for the condenser wire at the terminal post had turned in a way it was nearly touching the wall of the cap and allowing a spark to go to ground. That there was spark there didn't make sense, but then found that the fiber washer had creased or cracked or compressed enough that a good bit of energy was going straight to the cap and to ground.
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PostPost by: Billmack » Fri Jul 23, 2021 2:26 am

If there us spark at the coil wire and a good red rotor the possibilities are pretty limited. Sounds like something with the cap. Maybe wires on wrong??
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PostPost by: sprintsoft » Fri Jul 23, 2021 11:21 am

Hi Richard,

How are you verifying that there is no spark at the plugs?

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