Lotus Elan

Stalling when hot. UPDATE

PostPost by: Evante » Tue Jul 07, 2020 8:37 pm

Hi All,

About two weeks ago I posted about having problems starting my car. I got some great advice. Ultimately, my Petronics distributor was replaced and the car ran great!

That is, until it got to 90C (194F). Then it stalled out. Sometimes it would restart immediately, but other times, I had to wait for it to cool down then it would restart immediately, run great, then cut out at 90C, again. A 1500 pound car is easy to push by yourself until you get to hills.

I am now looking for some advice on what it might be. So here are the specifics:

• 1972 Federal Sprint with no emissions controls.
• It has a high balance pipe between the Strombergs.
• New sparkplugs
• New wires from Powerspark
• New Powerspark distributor cap
• New Powerspark electronic distributor
• Lucas Sport coil
• Mechanical fuel pump 3 years old
• Timing is set at 32degrees at 3,000 rpm

I first thought it might be the coil. I replaced it with another one and the same thing happened.
I was told that at high temps the carbs might be flooding the engine so I rebalanced and tuned the carbs-no luck.

Someone suggested the Powerspark electronic distributor might be bad.
Two people suggested a vapor lock.

Any thoughts?

As always, that your for your suggestions.

Jay S.
Last edited by Evante on Fri Jul 17, 2020 3:26 pm, edited 1 time in total.
Jay S.
1972 Federal Sprint, Colorado Orange/White
2005 Elise, sold
1988 Evante 140TC, sold
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PostPost by: Evante » Tue Jul 07, 2020 8:54 pm

Let me add this:
The engine stalls as the revs go down to idle.
Also, I tested to see if there was an air leak by spraying starter fluid where the carbs connect to the manifold and no change in rpms.

Thanks again!

Jay S.
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1988 Evante 140TC, sold
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PostPost by: mbell » Tue Jul 07, 2020 9:05 pm

First i be trying to work out if its a spark or carb issue. Maybe get one of the inline tester and see if your getting spark when it cuts out. Could also pull a plug and see if you get a spark when its earthed, but that harder to do at the side of the road.

Evante wrote:• Timing is set at 32degrees at 3,000 rpm


What is it at idle? Do you know how much advance the dizzy will have at that engine speed?
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Quart Meg Miles » Tue Jul 07, 2020 10:57 pm

Have a look at the petrol level in the fuel pump. When my car was in traffic after a fast run in hot weather the alcohol in the fuel vapourised and the bowl emptied, stalling the engine. Fitting an electric pump in the boot solved that problem (which may not be yours).
Meg

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PostPost by: sprintsoft » Wed Jul 08, 2020 12:17 am

Hi Jay,

Are you still getting the cough and backfiring you had before you replaced the Pertronix?

Can you tell us the static timing?

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PostPost by: Evante » Wed Jul 08, 2020 1:40 am

No Iian, the coughing and backfiring is gone. I took the Petronics distributor apart after I got it out and found that the carriage that held the four magnets had separated and one of the magnets had moved up into the top while three others were in their original position. This meant that one cylinder was not regularly firing as the magnet was not in reliably in the vicinity of the sensor. This problem was completely solved by the new Powerspark distributor.

I think that it may be the carbs because I noticed tonight when it started to die and I was pumping the gas to try to stop it from doing so, that gas was coming out of the float vent hole on the rear carb but not on the front carb. I had taken this apart before and the valve was working fine. I also emersed the float in gasoline and it did not sink so I do not think it is bad. Perhaps it is not set at the right clearance?

Any thoughts?
Jay S.
1972 Federal Sprint, Colorado Orange/White
2005 Elise, sold
1988 Evante 140TC, sold
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PostPost by: mbell » Wed Jul 08, 2020 2:58 am

Weber's?

If so if the fuel is coming out of the breather to the air box then your carbs are getting very flooded and they're is something wrong with float or needle valve.

I wouldn't be running the car like that due to fire risk from leaking fuel.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Evante » Wed Jul 08, 2020 3:19 am

Strombergs.
Jay S.
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PostPost by: 69S4 » Wed Jul 08, 2020 6:23 am

I had a similar problem many years ago when one of the needles came apart. The actual needle is held in a small brass cylinder with a spring to bias it to one side. That assembly had come apart and the needle had jammed about 4-5mm higher than it should be. The car would start from cold ok and run at highway speeds ok but hot idling was all over the place and hot restarting impossible. I only found out when that carb flooded (outside Blockbuster video - told you it was a while ago! :lol: ).

A couple of new needles and some tlc to the temperature compensators - making sure they were actually opening when the engine was hot - was the fix. As others have said, it also wouldn't hurt to check the needle valves are seating properly and the float level is correct - 17-18mm iirc.

I know you've done a lot of work on the ignition side but I once had similar symptoms with a bad (or in my case, wrong) rotor arm.
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PostPost by: alanr » Wed Jul 08, 2020 10:40 am

I would remove the Powerspark ignition and put it back on points and then see what happens.

Personally I am anti these electronic aftermarket ignition systems having seen so many times the problems they generate. They are usually made with short life junk chinese electronic components!
For a normal road car just keep it simple and keep it on points!

Alan.
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PostPost by: sprintsoft » Wed Jul 08, 2020 11:07 am

Jay,

Needle valves can 'look' fine but can still leak, and stick.

With your back carb flooding, and the other not, minimally you need to put in some new needle valves to properly eliminate these, then make sure your float levels are set correctly.

federal stromberg trail here...
https://lotuselan.net/forums/viewtopic.php?t=42511

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PostPost by: Evante » Wed Jul 08, 2020 11:57 am

Once again, thank you all for you all for your valuable and insightful input. You have all given me some good direction to go on.

I will get back to you with updates as I progress.

Stay safe.

Jay S.
Jay S.
1972 Federal Sprint, Colorado Orange/White
2005 Elise, sold
1988 Evante 140TC, sold
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PostPost by: Evante » Thu Jul 09, 2020 7:20 pm

Hi all,

Just posting a follow-up. Given the leaking of fuel out the vent hole on the Strombergs, I first remove the floatbowl from the rear carb. The needle valve was not stuck but it was sluggish so I replaced it and set the flat to the correct level.i then did the same on the front carb. I tested it twice now, getting up to 90c. No stalling so far. I will test it out a few more times just to make sure but it seems to be working well.

Thank you all once again for your help.

It takes a village to own aa Elan.

Best to all,

Jay S.
Jay S.
1972 Federal Sprint, Colorado Orange/White
2005 Elise, sold
1988 Evante 140TC, sold
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PostPost by: Evante » Fri Jul 17, 2020 3:40 pm

Hi All,

I finally got the problem fixed. After my last post, the engine continued to stall at 194 degrees so I had to go back to the drawing board. I went over all of the suggests that were made and still no luck. I was talking to Ray at RD Enterprizes becasue I ordered a set of points and condenser to eliminate the electronic ignition. He said that he thought it sounded like it was something electric because when the car stalled, it did not burble out it judt went dead, He also said it sounded like the coil but I had replaced the coil 2 times and it happeded with both.

I then remembered (in the middle of the night) that I had, some some reason I could not remember, attched a wire from the positive side of the coil to a hot lead on the solenoid. Do not ask me why. It makes no sense but I had done this when I rewired the car and it did not make any difference in how the car ran for 2 years until I changed out the Petronics ignition for a Powerspark. I think that the Powwerspark unit must have drawn more power and with this useless additional electrical input, the coil was getting too hot and would cut out. With the wire removed, the problem was solved. I have tested it out multiple times now and no stalling.

However, the tach stopped working completely. I just ordered an RVC unit from Spiyda to hopefully fix that problem.

I am embarrassed to admit that I added an unecessary hot lead wire to the coil, and caused my own problem, but there it is.

Thank you all for your input.

Best to all,

Jay S.
Jay S.
1972 Federal Sprint, Colorado Orange/White
2005 Elise, sold
1988 Evante 140TC, sold
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PostPost by: pharriso » Fri Jul 17, 2020 4:04 pm

Good to hear that you are running again reliably. Sometimes we handicap ourselves :oops:

Take it out & have a good blast!
Phil Harrison
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