Lotus Elan

Cough, cough

PostPost by: Robbie693 » Sat Sep 30, 2017 10:54 am

Hello,

Recently my Plus 2 has become a bit of a pig to drive in traffic/around town - I have to slip the clutch to get away without bogging down, giving it a bit of a blip beforehand to clear it's throat, and now and again it will cough violently accompanied by a smell of fuel when trying to pull away, requiring my to dip the clutch, rev, then try again.

On the open road and wide throttle openings it's ok. I haven't changed anything to prompt this behaviour as far as I know, just adjusted the balance between the carbs (Dellortos) now and again to see if I can improve things.

I was wondering if this was a sign of flooding? - I have re-set the float heights, they were way off (12mm), which made me think at the time I had found the problem but sadly it remained the same alas. They are 8.5g floats so I set them to 15mm. I was wondering if I should go to 16mm as suggested in the manual if flooding occurs but I'm not sure this is a flooding problem?

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PostPost by: LaikaTheDog » Sat Sep 30, 2017 3:10 pm

Sounds like it is running rich at idle causing carbon build up that clears with a blip.. I have the same but I intentionally run rich to avoid stumble on my webers at 2000rpm
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PostPost by: William2 » Sat Sep 30, 2017 5:36 pm

Hi Robbie, if it were me I would clean the filter on each carb union and whip out the idle jets and holders and blow through with compressed air just to be sure there are no bits of dirt anywhere. Are you sure that the carbs are correctly balanced. I set mine using a Synchrometer which seemed to work well enough. I also found that BPE6s plugs seemed not to foul up in traffic jams compared to BPE7s.
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PostPost by: alan.barker » Sun Oct 01, 2017 10:31 am

What fuel pump do you have fitted. Is it electric or mechanical replacement.
The all metal mechanical pumps produce too much pressure and need a pressure regulator in the line.
For the Dellorto carbs balance is easiest, best and quickest with Carbtune 4 columns.
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PostPost by: Robbie693 » Mon Oct 02, 2017 10:20 am

Thanks for the replys,

It is definitely running rich a bit, I get sooty plugs around the rim and brown staining on the rear valance and bumper. It was set up by Aldon to cure a stumble at about 2000rpm (if i remember correctly - it was a few years ago :oops: ) so I haven't played with the mixture screws for that reason, thinking that, if I haven't touched them, then the recent arrival of the problems must be something else...?

I have just had all the jets out and they seem fine, as were the filters. I have been running BPR7 for some time as I couldn't tell any difference to the 6's but I won't hurt to try the 6's again just to check.

I use a synchrometer to set the balance, I'm not sure I have the ports for a manometer system.

The Fuel pump is the standard AC mechanical, rebuilt by Brian B.

Will stick some BPR6 in and see what transpires

Cheers

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PostPost by: alan.barker » Mon Oct 02, 2017 11:48 am

If you have Dellorto carbs you have the manoports for sure.
Alan
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PostPost by: William2 » Mon Oct 02, 2017 3:52 pm

I don't think it is the case that the AC mechanical fuel pump produces too much pressure. If this were true every Elan would require a petrol regulator. I was under the impression that if anything the pressure was a bit marginal.
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PostPost by: alan.barker » Mon Oct 02, 2017 4:44 pm

Sorry,
but when i said all metal pumps i'm talking about the replacement all metal pumps. Without the glass bowl.
I think some of the all metal pumps are produced in India or somewhere.
I had this problem on a +2S130 when i fitted an all metal pump that was flooding the Dellorto carbs because of too much pressure. :shock:
The problem was flooding at tick over.
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PostPost by: Elanintheforest » Wed Oct 04, 2017 8:01 am

Put the BPR6 plugs back in Robbie. I'll bet that will sort it out.
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PostPost by: Robbie693 » Tue Apr 24, 2018 10:50 am

Resurrecting this one as I have found the cause.

New plugs didn't help unfortunately and the low-rev running continued to be poor but on a recent post lay-up test drive the car broke down in a similar way to when I had problems with a failing electronic ignition module - misfiring, reluctance to rev, followed by dying when the clutch was disengaged and loud backfire when trying to restart.

In an effort to get going enough to limp home I fitted the old ignition module which I new worked until the engine got hot and managed to get it running. Performance was much better than it has been for months during the 2 miles I had to get home so it looks like I have another failed module.

I believe the failures a due to heat breakdown but I'm not blaming the module itself (Powerspark) as I know that my engine runs hot - it is the reason I could never get it to work with points/condensor - and the new radiator only just keeps things in check, constantly cycling the fan...

So now I'm wondering wether to get another Powerspark and accept that they have a limited life-span in my car, or look into other electronic ignition options.

So if anyone has any experience of failures with electronic ignition systems for whatever reason I'd love to hear about it and what make it is!?

Cheers

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PostPost by: Hawksfield » Tue Apr 24, 2018 1:36 pm

Robbie

Fit lumenition optronic fit and forget :)
25 years a believer
Regards

John

+2s130 1971
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PostPost by: JonB » Tue Apr 24, 2018 5:22 pm

I'm wondering if he's treating the symptom rather than the underlying cause.

Maybe an updated radiator to help cool things down first?
1973 Elan Plus 2S 130/5 - UK - Chassis 50/1115L
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PostPost by: pauljones » Tue Apr 24, 2018 6:49 pm

I used an Aldon ignitor 2 module, flame thrower coil and 8mm leads. Years ago i quoted in a post that you could see the spark from space.
I also swaped to bosche super 4 plugs.

Cant remember the cost of it all but i still have it in case i want to ditch the EfI.

If you can get to them i believe they can fit it all and Rolling Road setup too.
Kick the tyres and light them fires...!!!!!!!
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PostPost by: RichC » Tue Apr 24, 2018 7:42 pm

exactly the same problems .. drove me crackers kept blaming the modules for overheating .. one after the other .... ended up checking out electrics with a multimeter & concluded there was a hidden ballast in the system somewhere so swapped for EI module to work with ballasted system and worked fine ever since
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PostPost by: Robbie693 » Wed Apr 25, 2018 8:10 am

Thanks chaps,

the radiator is a new one, a Fat Boy with modern shrouded fan.

I have considered the Optronic as I had one before on another car and as far as I remember it worked perfectly, I don't really like the look of the control unit but it may mean I can position it somewhere cooler...

The Aldon unit is very similar the the Powerspark visually, I believe it is the same as the Petronix. I do recall someone having problems with them breaking down but I can't find the post now.

Rich - I have considered the possibility of a ballast resistor many times but I can't find one anywhere, think I need to get the multimeter out and check properly (I might have done this before but I really can't remember! :oops: ) Where did you find yours?

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