my Eclat is a very naughty boy!

[Tim Jones]

My 1979 Eclat (which I’ve owned for 25 years) dumped me at the side of the road again this Sunday

I will try to describe what happened in as much detail as possible to see if it puts any light bulbs on your end.There is some similarity with what happened on a previous run. Let's start with that previous run.

 I took it out for a run on a local motorway.

The car cruised well at 70mph, I was in 5th most of the time but occasionally would drop it to 4th to let the engine have a few moments at higher revs. Ran well, pulled well, no hesitation at those sorts of speeds. After about 23 or so miles, I ran out of Motorway so took an exit to do a U-turn and come home. As I hit the roundabout at the bottom of the exit, the car fluffed and almost died - I gave it some throttle and it reluctantly came back and then recovered and drove without issue on the Motorway until I left it to reach my house. It started to run poorly in the last mile (I live within a mile of the exit from the dual carriageway) and felt like it was running on 3 cylinders by the time I got home. Assume running rich and fouling plugs.

 I took it out on Sunday just gone. I'm on a dual carriageway, cruising at 70mph. Car running sweet as a nut. At one point, I had to drop to 50 to go through a restricted speed area in a town but still no problems. Dropped to 4th. Out the other side, and picked up to 70 again. No hesitation, no issues at all. Done about 46 miles, Temperature, Oil pressure and Volts all good.

 Now, that road is mostly uninterrupted with conventional exit ramps but there are two occasions when there are roundabouts. As I hit the first roundabout, into 4th, into 3rd, as I tried to pull away, it fluffed (but then there is a massive mid-range flat-spot which needs looking at. Gave it some throttle and it came back. Put it down to the flat spot. Back to cruising nicely at motorway speeds. Reached a second roundabout - hit 4th, hit 3rd - it died and I couldn't catch it. Stationary at side of road. Tried to restart it repeatedly but not a sniff.

 It took the RAC a little over an hour to reach me, by which time, it has started again. I wondered about trying to drive it home but felt in my bones it would fail again and ended up being recovered.

 So - what happened? I can't help thinking that the fact that 3 times, it hasn't liked dropping from motorway speeds to roundabout speeds has to be relevant, does it not? It has, for many, many years, had an intermittent fault where it would cut out but then start later when it had cooled down but I thought Lotusbits had got to the bottom of that when they changed the electronic ignition from Lumenition Optronic to Lucas (I seem to recall they also did something with the coil / ballast resister). So I'd like to think it's not that again.

 But because of the above, I've always thought this is an intermittent electrical failure, but why would it get arsey when I stop cruising at motorway speeds and hit a roundabout? Isn't that more likely to be a fuel issue? . Some sort of fuel surge? (but I didn’t brake hard – everything was super gentle) Could it have instantaneously flooded and fouled its plugs as I hit the roundabout? I find that hard to believe but it would fit the timing of events. Would those plugs have dried themselves in the hour it was standing?

 Very dispiriting. Any ideas out there?

[Dan E]

Sounds terminal, wanna sell it? 😂

[Tim Jones]

Good effort Danny - having put up with him for 35 years, I think I'll hang on in there

 

[Dan E]

Looks stunning mate love it. Unfortunately can’t help you out any further than that. Someone on here will know though 

[williamtherebel]

My old problem with my Eclat (30 years +) doesn't really sound the same as yours, although there are similarities. Anyway see what you think :- Running about town there were no problems. However, if I went on long runs, sometimes it would falter then cut out completely. If I waited for a time it would start again and everything would be ok. This happened on a number of occaisions. Drove me nuts.  🤬 Checked everything more than once. In the end one day I just happened to be filling up with petrol and when I twisted the filler cap there was a great intake of air. Then the penny dropped. My breather pipe was completely blocked. The filler cap was a very good fit, so on a long journey a vacuum formed in the petrol tank until the fuel pump could no longer compete with the vacuum and so the car died through lack of fuel. If I waited long enough some air would get back into the system so when I tried to fire her up again it worked. Sorry for the long winded explanation. I should have just said "see if your breather pipe is blocked"!  Worth a try anyway. Hope you get it sorted.

[esprit s2]

Does it fire up ok from cold? Idle well? 

Timing issue maybe is what I'm thinking.

[USAndretti42]

Fuel vapourisation?  Runs OK at high revs/throttle when fuel flow is relatively high.  Underbonnet temps get up there.  Slow for roundabout and close the throttle and fuel flow drops to idle levels. Fuel heats up and boils in the line causing vapour lock and stopping flow of fuel to carbs.  Leave it to cool.  Vapour condenses and allows fuel throught to float chambers and alls well again.

[Escape]

Could it be ignition? Even though that has been looked at. Maye the coil heats up at high speeds, and when you slow down the airflow decreases pushing the temperature beyond the limit? If you can accelerate again, airflow picks up and temperature drops, but if you can't catch it, it stalls and heatsoak prevents it from starting again. Just a theory, and probably hard to check due to the very specific circumstances.

Filip

[directordanw]

My Eclat had very similar symptoms, ran fine on the motorway but then (random) power loss once I was running it a bit slower - but only after the engine had had a good long run fully warmed up.  I tried EVERYTHING - all of the suggestions above and more.  In the end I discovered two tiny splits in the O rings that form part of the mounting between carbs and manifold.  Clearly once the engine had warmed up something was expanding and then the reduced airflow running at lower speeds meant that there was a big vacuum leak generated in the manifold once off the motorway because of different heating/cooling times - hence starving the engine of fuel.  It took me weeks to find this!  Good luck!

[ramjet]

I would also check the earth wire on the fuel pump. Easy to do and I found several earths on my car which does not have to put up with the environmental factors that you guys do.

[jason.goad]

Have you got a rivited rotor arm ?

[silverfrost]

Pop an new coil on it, not expensive and easy to fit they can pack up given a rise in temprature when they are on their last legs,

[black eclat]

Try fuel cut off solenoid. Mine was loose on the chassis (so poor earth). Mine gave me all sorts of spurious loss of power issues until I discovered that.

(I also had the vacuum issue in the fuel tank)

[Tim Jones]

Thanks to everyone who took the time to respond. It's much appreciated and quite a few different things to consider there.

I don't think it's the blocked breather pipe to the fuel tank (mostly because I can't see that this would sync with slowing from cruising speed to slow speed) but propose to run with a temporary fuel cap which will be drilled to vent it just to rule it out.

With regards to the perennial issue of bad earths, I'm considering having temporary secondary earths run from all key components straight to the battery, probably terminating in a cluster of bullet connectors so I can enable/disable the secondary earths on a per component basis to try to isolate which one (if any) may be faulty. The way I look at it, if the fault still exists after that, it probably isn't a bad earth and I'll remove the temporary earthing wires. I'm thinking fuel pump, coil, electronic ignition and fuel cut-off solenoid (I don't even know where the latter is)

The coil is only a few hundred miles old (indeed, everything ignition wise is only a few hundred miles old) but I am considering fitting a spare coil in a disconnected state so if the fault occurs, I can swap the connectors from the original coil to the spare coil - if it starts, then at least I can focus on the coil (but why is it failing is a different question)

I personally don't think this is under-bonnet temperature issue - it was relatively early in the day - it wasn't warm and only seconds had passed between running perfectly fine on a dual carriageway and it failing as I hit a roundabout at the bottom of the exit ramp - temperatures couldn't vary that much that quickly. That makes me think it isn't fuel vapourisation (but what do I know)

Cheers all

Tim

[Dunc]

Which coil?

Has someone perhaps fitted a 12V coil to your car which has a requirment for a Balasted coil?

[Tim Jones]

Hi Dunc - I think it is a 12V coil but it was done by Mike at Lotusbits who was fully aware of any ballast resister issues

[Dunc]

Tim,

PM me your address and I will post you a known good fuel pump to try. I will need it back however after you've tested the car with my pump.

Cheers

Dunc

[tom kilner]

Fuel cut off solenoid should be low down on the rh chassis inside the engine bay (bottom right in worm's eye view photo) - fuel pipe comes in the back from the transmission tunnel and output comes up towards the carbs. Electrical connection makes a clunk when switched.

Can't see how it would cut out at roundabouts though,  but a test and a wiggle, and maybe clean the clamps, easy to eliminate it from the suspects list.

[Drawfiler]

Tim

Run the car and then feel the coil, if it is hot that's your problem, change it for a resin filled one, as the oild coil warms up it expands and faulty wiring inside can break up, it will then work intermittently..