Area Representative marcos59 Posted March 30, 2015 Area Representative Share Posted March 30, 2015 Sorry for poor english but you should mostly understand and I hope be able to help.On Xflow twin Weber Lucas Electronic ignition:Each time after 30mn blatting engine start to misfire with pop and bags from exhaust then cut off few hundred meters later.Engine can't be started again before 10mn and fresh fuel can be seen leaking/dripping between carbs and inlet manifoldIt seem engine have too much fuel or do not burn it anymoreWhat have been done (without any success) - Fuel pressure tested (was a bit high) - Needle valve exchange - Float chamber level (One was fairly out) Question is: Is it a carb or ignition problem ? - If ignition problem: How fresh fuel can leak between carbs and manifold ? Without ignition unburned fuel should go through exhaust only isn't it ? - If Carbs problem why always after 30mn ? and why some bangs like and ignition problem?Help very welcome..very annoying problem. I can't use my car only by 30mn run ! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 30, 2015 Member Share Posted March 30, 2015 Deleted Link to comment Share on other sites More sharing options...
revilla Posted March 30, 2015 Share Posted March 30, 2015 30 minutes to me sounds temperature related. Is it possible that you have two problems, a leak somewhere around the carbs and maybe something on the ignition side breaking down when it gets hot? I'm thinking coil or condenser? I guess it's just about possible if something around the carbs or manifold is not properly tight it may start to leak as things heat up and expand but sounds unlikely. Just one other thought ... it is definitely fuel and not water leaking? I don't know much about the crossflow setup but some engines pass water through the inlet manifold to warm it and if the gasket has gone it may both leak water and ingest it into the engine, upsetting the ignition, particularly when it gets hot and pressurised. May be completely on the wrong track, but just a couple of things to think about. Link to comment Share on other sites More sharing options...
Area Representative marcos59 Posted March 30, 2015 Author Area Representative Share Posted March 30, 2015 Thanks for your comments. Definitively not water..I'm happy it is a Xflow and not pre Xflow (It have burnt !) Link to comment Share on other sites More sharing options...
john g Posted March 30, 2015 Share Posted March 30, 2015 I had a similar issue a couple of years ago after winter hibernation, didn't have leaking fuel but had the not running after 30 minutes. It turned out to be dodgy spark plugs, getting hot and breaking down. The plugs, at the time had been replaced the year previously so had only done a couple of thousand miles, however they, or at least one of them was the culprit. Link to comment Share on other sites More sharing options...
OliverSedlacek Posted March 30, 2015 Share Posted March 30, 2015 30 mins and I'd bet it's ignition. I would try changing the coil as it matches the symptoms very well. Link to comment Share on other sites More sharing options...
SM25T Posted March 30, 2015 Share Posted March 30, 2015 Or blocked vent in fuel filler .... not allowing air in to the tank ? When it stops, try taking the fuel filler cap off and see if there is a rush of air into the tank ? Link to comment Share on other sites More sharing options...
DJ. Posted March 30, 2015 Share Posted March 30, 2015 I'd bet the coil is the problem too. Duncan Link to comment Share on other sites More sharing options...
F355GTS Posted March 30, 2015 Share Posted March 30, 2015 My BDR would behave like this, turned out to be bad main connections on the Alternator. Does the rev counter misbehave when you get the problem? I have a spare Lucas DLB101 coil here if it helps Link to comment Share on other sites More sharing options...
6speedmanual Posted March 31, 2015 Share Posted March 31, 2015 I too vote for ignition. I had near identical problem on SAAB V4. Was the king lead breaking down when hot. Link to comment Share on other sites More sharing options...
DaveMorris Posted March 31, 2015 Share Posted March 31, 2015 I would vote for it being the coil also.(Just out of interest - what orientation do you have the coil. Vertical, horizontal or at 45degres ?)D Link to comment Share on other sites More sharing options...
Molecular--Bob Posted March 31, 2015 Share Posted March 31, 2015 I had much the same when mine had a crossflow in it, I went through most of the above before taking it to a garage and as luck would have it they had an old school mechanic who went straight to the distributor and gave it a twist. The locking clamp had come loose and the timing had moved. It ran well when cold, but as soon as it got hot it wouldn't hold load and miss-fired. Not saying this is your problem, but check your timing before you change the expensive stuff.If I can find my thread I will edit this to add a link. Link to comment Share on other sites More sharing options...
Nigel Riches Posted March 31, 2015 Share Posted March 31, 2015 Ok, just to throw in a different angle. My uncle had a Mk 3 cortina, from cold would start no problem, run for a while, a few miles and expire, leave it ten minutes and off it would go again, only to repeat the previous scenario.Turned out the baffles and packing in the silencer had collapsed, partially blocking the back of the silencer, restricting the exhaust gas flow, so not allowing new fuel charges into the cylinders, a new silencer sorted the problem. Might be worth a look at your exhaust system. Regards, Nigel. Link to comment Share on other sites More sharing options...
Area Representative Nick Bassett Posted March 31, 2015 Area Representative Share Posted March 31, 2015 Not sure if this helps, but here goes... many, many years ago I owned a Mini 1000 that my Dad helped me to modify one summer with a LCB exhaust and large bore system etc. The car started fine and would run for 5 mins without issue, then would cut out. Dead. Leave it for 10 mins and it would start again, but only run for 5 mins and the whole cycle would start again.The problem? The battery lead that ran the whole length of the car from the boot was fouling the new (larger bore) exhaust and as the exhaust heated up it melted the plastic insulating layer on the battery cable which then shorted out. Easily fixed once the problem was found, but there was a bit of head scratching!!!Sound similar to your issue - could something be heating up and cutting out as a result? Link to comment Share on other sites More sharing options...
David Brown Posted March 31, 2015 Share Posted March 31, 2015 Perhaps from a different angle. On a Morris 1000 I had many years ago it did this. Found it was a blocked breather on the fuel cap so tank was under suction. Remedy was to remove the cap and the tank then filled with a whoosh and a bong.Really impressed my soon to be father in law who took us for a run in his brand new Wolsey 1800. Exhibited the same symptons which I was able to resolve in 30 seconds. He couldn't believe the instant diagnosis and fix. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted March 31, 2015 Share Posted March 31, 2015 If you have fuel leaking from the carbs it's unlikely to be the filler cap as this being blocked will result in fuel starvation. Irrespective of the engine cutting out, you do need to stop this leak or you could have a fire! I suppose if the filler cap is blocked and the car is getting very hot, the pressure might build up in the tank causing the fuel to be over pressurised, but very unlikely.Do you have and use the fuel enrichment device (choke)? These are notorious for causing problems although I would expect symptoms sooner than 30 minutes. If you use the choke, these devices can stick and leak lots of fuel into the carbs and make it run very badly if at all. It might also explain the fuel leak.There's a bit more about the symptoms and cure here.Paul Link to comment Share on other sites More sharing options...
Roger King Posted March 31, 2015 Share Posted March 31, 2015 Fuel leaks from the flexible mounts between the carbs and inlet manifold are standard I'm afraid: fuel is a real escapologist when it comes to getting past 'O' ring seals. All you are probably seeing is the little puddle of fuel that is inevitably left at the back of the carbs when you switch off seeping past the 'O' rings. It's a little difficult to describe this as nothing to worry about seeing as it is fuel dripping out, but nearly all installations with DCOE's do it and it can be regarded as normal.It's not possible to diagnose your problem for certain, but I would definitely follow some of the advice above and look at the coil and fuel tank breather. The coil can sometimes fail as it warms up and a blocked breather can take some time to stop fuel getting to the carbs (it won't necessarily stop the drips described above though).You have also used the dreaded words "Lucas Electronic Ignition" (American joke - why do Limeys drink warm beer........... because their fridges are made by Lucas). The Lucas Constant Energy competition systems are brilliant, but you may well have the Hall Effect QDB100 system. Caterham fitted this to many cars as standard and it is the worst ignition system I have ever had the misfortune to work with (read "throw away" for "work with"). It's easy to tell if you have this by looking at the rotor arm; if it has a slotted steel skirt of around 1.5" diameter hanging down from the rotor arm itself, you have this plague. Aside from the weak spark it gives, the rotor arm works loose on the distributor shaft. Normally this wouldn't be a major problem, but unbelievably Lucas chose to use the slotted skirt to signal the spark to fire. What this means in reality is that your ignition timing goes all over the place when the rotor arm suffers wear; seriously, we're not talking about a couple of degrees variation here, but tens of degrees. THROW THIS THING AWAY and employ a man with a box of matches to light each cylinder manually at the correct time, or failing that, get another (any other) system. Link to comment Share on other sites More sharing options...
elie boone Posted March 31, 2015 Share Posted March 31, 2015 Nicolas, Like Roger said most likely the ign, do you have a good spark when it stops ? does the coil get hot ? if you need a other dizzy i think i have a spare, fore sure a spare one of that dreadfull Lucas system with electronic box u can have for free and i think i have another dizzy with points. Link to comment Share on other sites More sharing options...
Area Representative marcos59 Posted March 31, 2015 Author Area Representative Share Posted March 31, 2015 Thanks for all comments I will investigate further this WE If it can help: Problem occur after 30mn from cold but after first stop it occur far more fastly. Yes coil and amplifier are a bit hot but not too much (look normal to me)To Roger: - Fuel leak is not a "normal" caramel residual unburned fuel. It is fresh clear fuel dropping +-1 drop every 5 secondes after car stop during few minutes before it start again. Is a car rolling few hundred meters without ignition could over fill carbs and create a leak ? - Lucas ignition look like that: Is it the bad one ?To SM25T: A quick look (need to double check) do not show any vent on this old 80's steel tank..but it have a beautiful 00's mocal fuel filler(and far more airtight than 80's ones) ..so need to investigate your idea further.To Elie: Thanks for your offer about spare parts. I will investigate everything else before and come back to you Link to comment Share on other sites More sharing options...
SM25T Posted March 31, 2015 Share Posted March 31, 2015 Check for the inrush of air. That's the best clue. Link to comment Share on other sites More sharing options...
Roger King Posted April 1, 2015 Share Posted April 1, 2015 First, the bad news - I mean fresh fuel dripping as you describe; I reckon around 70% of DCOE installations do it. Setting the correct float level can sometimes make a small difference, but a new set of 'O' rings and facing off the manifold and rear faces of the carburettors can also help. For what it's worth, I once replaced an old fashioned cork seal fuel tap on my lawnmower with a modern one using an 'O' ring seal - it leaked continuously when in the closed position. It seems that fuel is able to seep past 'O' ring seals.Now the really bad news - you have the QDB100 igntion system. Get rid of it and your problems may well go away. If you have a Bosch distributor, then fitting something like a Lumenition kit to it will be a vast improvement, but if you have the Lucas so called "unleaded" distributor, junk the whole lot and fit a new system with a new distributor that has the normal Ford advance curve. The Bosch has the correct advance curve already whereas the "unleaded" distributor leaves you with around 10 degrees too little advance at high revs. The difference in performance is quite substantial. Link to comment Share on other sites More sharing options...
elie boone Posted April 1, 2015 Share Posted April 1, 2015 I think i also have a Fiesta MK1 Bosch Dizzy, Not sure about advance curve on these. Aldon sells a ignitor kit to fit neatly inside the dizzy. IMHO if it was a overfuelling problem you wouldn.d be able to restart after 10 min, it would take more if the plugs where wet with fuel Link to comment Share on other sites More sharing options...
OliverSedlacek Posted April 1, 2015 Share Posted April 1, 2015 Just to second Roger,a drop of fuel every few seconds is quite common and although undesirable is unlikely to be the cause of any problems.It's also worth bearing in mind that a Megajolt mapped 3D ignition is comparable in cost to a new distributor + electronic ignition and gives substantially better torque and fuel consumption. Link to comment Share on other sites More sharing options...
harrebe Posted April 1, 2015 Share Posted April 1, 2015 Nicolas, how about installing a Megajolt system.?I did that 2 years ago and the improvement(s) are significant.Hope your weird problem will be solved quickly.Bas. Link to comment Share on other sites More sharing options...
Roger King Posted April 2, 2015 Share Posted April 2, 2015 The Megajolt appeared on the scene after I stopped building engines so I have no hands on experience with it, but as a matter of principle a well mapped and reliable 3D system will certainly be vastly superior to a simple distributor.If set up properly you can expect improved throttle response, an increase in part throttle torque and better economy. Link to comment Share on other sites More sharing options...
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