Lotus Elan

No spark until key is released

PostPost by: Flightmate » Fri Jun 24, 2016 9:54 pm

I appreciate any thoughts as to where to look first. I don't have the original points to swap back in, so if the ignition is suspect I would just have to replace it and see what happens.
Last edited by Flightmate on Mon Sep 11, 2017 8:58 pm, edited 1 time in total.
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PostPost by: rgh0 » Fri Jun 24, 2016 11:38 pm

Did the car originally have a ballast coil system? If the start wire was disconnected and the run wire used for the replacement electronic system then you would get your symptoms.

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PostPost by: elancoupe » Sat Jun 25, 2016 1:26 am

I had a very similar problem on my car a couple years ago. Intermittent poor running, which progressed to hard/no start, also intermittent. I swapped out coil, wires, plugs and Pertronix unit to no avail.

The key to me fixing mine was the spark when the ignition was released. This made me think that the ignition switch was the problem, and indeed, a new switch cured the ills.
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PostPost by: DuncanC » Sat Jun 25, 2016 2:14 am

You might be able to jumper the wires attached to the ignition switch to ensure that current flows to the coil when cranking, and that might prove whether or not it's the switch.

The performance issues could be unrelated to either the switch or the Pertronix unit. Improper ignition timing or improperly working mechanical advance can cause lower power at high rpm. Plug wires need replacement? Carbon tracking inside the distributor cap (hard to see with the black caps)? Is the coil overheating?

I hesitate to mention fuel feed issues since conventional wisdom says that most suspected fuel problems turn out to be ignition related. Disconnect the fuel line at the carb and see how much fuel flows from the hose when the fuel pump is running -- the demand may be exceeding the supply. If using non-ethanol fuel, water droplets can restrict flow through a fine enough mesh filter. Did you already try changing the fuel filter? Old rubber hoses sometimes develop an internal separation, causing a flap of rubber to partially block the flow. I once found a tiny V-shaped cut in a fuel line on a BMW. It was at the high point in the system, so it didn't leak liquid fuel but since it was upstream from the pump so it would suck air and cause loss of power, particularly when the engine's torque would cause it to shift, the bend the hose formed a tighter curve and caused the the cut in the hose to open up.
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PostPost by: Flightmate » Sat Jun 25, 2016 2:33 am

Rohan, I'm not sure if the car originally had a ballast system. I don't see a resistor anywhere unless it is tucked way back behind the panel where I can't find it. I see the 3 wires coming through the firewall on the right side. One going to the starter and two white wires going to the top of the pertronix coil. I'm not sure what each is for. Could those two be put on backwards? Would it hurt to try to swap them?

Elancoupe, that is a definite possibility that I hadn't thought of.

DuncanC, I have not yet looked into the fuel side. Since the car is fairly new to me it definitely wouldn't hurt to run through some of those things such as the fuel filter and check the flow the pump is putting out. Is there a good rule as to how much fuel I should see flowing out of the hose? Also should probably do plug wires either way even though they look fairly new I have no idea when they were replaced last.

Thanks!
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PostPost by: DuncanC » Sat Jun 25, 2016 3:34 am

Standard rule of thumb usage for fuel is 1/2 lb per hour per horsepower, so for 120 hp at 6 lbs per gallon, you'd need 10 gallons per hour or 0.167 US gallons per minute = 21 oz per minute or one ounce about every three seconds. That assumes no friction loss, so I'd bump it up to a ounce every two seconds as being a safe minimum flow level.
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PostPost by: DuncanC » Sat Jun 25, 2016 3:35 am

Find out if the flame thrower coil has an internal resistor -- it might, and in that case you would not need the external one.
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PostPost by: Flightmate » Sat Jun 25, 2016 1:40 pm

I pulled the coil out of it's strap and the markings on the bottom were 11P12 which looks to be an original or original replacement from what I can find online.
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PostPost by: DavidLB » Sat Jun 25, 2016 8:26 pm

Had exactly that problem on a sprint years ago, it was the ballast wires on the wrong terminals
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PostPost by: LaikaTheDog » Sun Jun 26, 2016 10:06 am

Just to be differect.
I had same symptom. It turned out that the white feed to the coil was on the incorrect ignition switch terminal. There is one terminal which is live when the engine is running but is dead when you turn the key to engage the solenoid.
I couldn't understand why I wasn't getting a spark during turnover until I noticed I was as soon as I stopped cranking...very difficult to start when you only have a single spark !
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PostPost by: Flightmate » Sun Jun 26, 2016 12:48 pm

Since I have two of what look to be identical white wires running to the coil would it hurt to swap them on the coil? Can I do any damage trying that? One has some blue tape on it which I'm sure was used to try to distinguish the two when hooking them up. I could easily see the owner getting them crossed at some point.
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PostPost by: rgh0 » Sun Jun 26, 2016 12:53 pm

you appear to have two other wires ( red and black) going to the coil what are those for ?
The white wires also appear non standard so all 4 could be doing anything.
I would try to understand what each wire is before swapping things around

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PostPost by: Flightmate » Sun Jun 26, 2016 2:12 pm

The distributer where the red and black wires end up. It is kind of hard to see the black wire, but it comes out of the wire sleeve with the red and is running just under it. It connects just under it in the distributer.
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PostPost by: Craven » Sun Jun 26, 2016 7:15 pm

My interpretation of the wiring is : -
White wire through bulkhead is the live ( + 12v ) from the ignition switch, needs to be there in normal run key position and is the feed to the coil.
White wire with blue tape is the pulse for the rev counter. From coil ? terminal.
Red wire on coil is the live feed to the ignition unit in the distributor the coil + terminal is used as a junction point.
Black wire is the switching pulse for the coil, coil ? terminal.
FWIW
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PostPost by: Flightmate » Mon Jun 27, 2016 2:42 am

Can anyone help me on which is the normal run position to check to see if the power wire is connected correctly?
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