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I have owned a July '67 TR4A IRS RHD for a couple of months now. Fuel-wise, I don't believe the car has been converted but know it had run ok in the past on good unleaded fuel. The other day I took her out for a short run and saw the fuel gauge getting close to the "E". Stopping at the garage I dropped in some Castrol classic valve master plus Lead additive to exactly equate to 25 its of super unleaded fuel which I poured in straight after.

However, about half a mile from pulling out of the garage the car suddenly coughed and spluttered and began to misfire. A couple of actual backfires then followed and she really started to vibrate too. I immediately headed for home quite gingerly but did try to check acceleration in case it was simply some tank deposits which needed blowing through. I stopped a couple of times too and standstill tick over sounded ok but low rev vibration was still there and you could tell a loss of power in 3rd and 4th gear too.

I left her a few days hoping it may have just been a temporary blockage but tried to drive the car today and the same misfire and vibration exists with some additional knocking underneath the car, which felt like it was along the route of one of the exhausts, probably a result of the amount of vibration from the engine not turning over smoothly. I'm really quite mystified, as she had been purring beautifully since getting her in August and all I did was refill with the same lead and unleaded mix as before. What would be the list of things I'd need to check?

Any thoughts gratefully received.

GJI

 

 

 

 

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Are you sure it was petrol you filled up with? 

That is how my car went when I topped it with diesel a couple of years ago.  The Shell Super diesel pump was next to the Super unleaded.  My fault for not looking.

To check - Open the filler cap of the tank and take a sample out by dipping a clean wooden stick in, withdrawing it and then smell the wet bit of stick. - It should stink of petrol and not feel slippery when rubbed between the fingers.

Cheers

Peter W

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If you have filled up with diesel there would usually be a good deal of smoke.

Pull off the fuel pipe at the carb end and see if fuel flows freely - if it does then it's unlikely that the tank is blocked.

Condensors are a significant issue these days and if one goes it may well run like a dog, backfire and possibly stop altogether, so don't assume it was just fuel as a possible culprit

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22 hours ago, BlueTR3A-5EKT said:

Are you sure it was petrol you filled up with? 

That is how my car went when I topped it with diesel a couple of years ago.  The Shell Super diesel pump was next to the Super unleaded.  My fault for not looking.

To check - Open the filler cap of the tank and take a sample out by dipping a clean wooden stick in, withdrawing it and then smell the wet bit of stick. - It should stink of petrol and not feel slippery when rubbed between the fingers.

Cheers

Peter W

Many thx Peter for replying. Yes, I did worry about that but can confirm it was def Super Unleaded and the same hose I've used on past fill-ups. Useful tip though on how to check for diesel in tank.

BTW..do any of you know if there's a super quality tech manual for TR$A's even beyond Haynes. Someone suggested I ask you. thx, GJI

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22 hours ago, stillp said:

Is the filter in the fuel pump clear? You might have disturbed some crud on the bottom of the tank when you filled up.

Nice looking car!

Pete

Thx Pete. Good thought. I'm a bit of a novice under bonnet so need to learn quick. Is this the filter? If so, should there be an element in it to stop crud entering engine?

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4 hours ago, Andy Moltu said:

If you have filled up with diesel there would usually be a good deal of smoke.

Pull off the fuel pipe at the carb end and see if fuel flows freely - if it does then it's unlikely that the tank is blocked.

Condensors are a significant issue these days and if one goes it may well run like a dog, backfire and possibly stop altogether, so don't assume it was just fuel as a possible culprit

Thx Andy. That's a whole new thing to me. Will research the condensers. It all happened quite suddenly. Maybe filling up was just coincidental 

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On 10/13/2019 at 9:27 PM, Gordon Irish said:

However, about half a mile from pulling out of the garage the car suddenly coughed and spluttered and began to misfire. A couple of actual backfires then followed and she really started to vibrate too. I immediately headed for home quite gingerly but did try to check acceleration in case it was simply some tank deposits which needed blowing through. I stopped a couple of times too and standstill tick over sounded ok but low rev vibration was still there and you could tell a loss of power in 3rd and 4th gear too.

I suspect the timing of this new dilemma is coincidental to adding fresh fuel., not least because unless you've drawn in water with your fuel - I don't associate backfires with fuel  but rather ignition. And tick-over vibration most often relates to just one or two cylinders not firing,  something inside breaking or jumping adjustment, or an engine mount not being secure  ..whereas generic fuel problems tend to effect all cylinders.  Because  'something inside breaking or jumping adjustment '  is horribly pessimistic, and in any case often accompanied by odd noises from inside the engine (even at tick over) - my approach would be to start off by checking the HT leads and spark plugs.   

Indeed with any such mystery - I remind myself of the basic workings of an internal combustion engines, and systematically check (..but unless very obviously wrong - not adjust) those.   Not knowing exactly how " bit of a novice under bonnet"  you are - I'll explain, but my please accept my apologies if I'm teaching grandma to blow an egg.  

The basics are  1. spark,  2. fuel,  3. timing (of both ignition and and valve opening), and 4. compression.  And each of these need to be roughly close to tolerance for each cylinder.  And 'the process'  is one of elimination. ie. if you check something works fine ..then you can eliminate it from being the fault.   I've numbered ' the basics' in order of being most commonly at fault on an engine which was previously running normally.    

So, if in your situation, having already thought through the fuel issues, I would start by first checking the HT lead on each plug.   So, start the engine and when warm enough to have a steady slow tick-over -  pull the HT lead off just one plug at a time (wearing rubber gloves or with rubber handled grips / pliers - to save you getting a high voltage shock)  ..and listening to hear for a difference in engine note.   If, when you pull a HT lead cap off, there is no difference in engine speed then that plug or lead is faulty.  

Even if that doesn't identify the issue,  because it's a quick job to do, and so quickly things to eliminate - I'd move on to systematically removing each plug to check its gap and condition.  At the same time you'll be visually checking the condition of each HT lead and cap - for cracks in the insulation, security of the cap onto the lead, and for corrosion, and to check for a positive lock of the cap onto the spark plug.  Also for any chafing of the lead itself along its whole length.  

While each plug is out, check its spark by refitting its cap and resting the threaded part of the plug against the cast iron cylinder head. When turning the engine over you're looking for a small but sharp, bluish spark across its electrodes.  NB. This doesn't check the sparkplug as much as the HT leads, because a spark plug can work (just OK) at tick over but falter when engine revs are applied.  Having said that, a big whitish coloured spark is likely to be faulty spark plug.  Substitution with a set of known-to-be-good plugs, set to the right gap, is the easiest way to eliminate those from the list of suspects.   

If the spark isn't good on each plug - then go one step up-line and check the points. The contact breaker points gap should be something like 15 thou - which is much the same as ordinary copy paper folded three or four times.  Prise the contacts' gap open with a small screwdriver to see if they are clean and bright, or whether they are dark and pitted. If it looks fine then don't touch or adjust things.  When turning the engine over with the cap off - the points gap's spark should be a barely visible bluish crackle, not a big spark which usually indicates a faulty condenser.  Also feel the distributor to ensure it's clamped securely to the engine block, so it doesn't turn.  Carefully also visually check the distributor cap for cracks and cleanliness. Either might be a path to loose your spark through.  Also check the HT lead between the coil and the distributor and it's connections, as well as the small wire feeding power to the points.  

If all that checks out as fine - great you can eliminate 'spark'  from the list of being the potential fault. 

From the photograph I see you have fuel in the bowl.  Undo the clip to drop that glass and see and smell the petrol is fresh and not contaminated with water or debris from the almost empty fuel tank. There should be a fine gauze filter on the underside of the aluminium housing.  Assuming the fuel and filter is clean then carefully refit the glass, taking care to feel that it sits flat on its seal before the clip is refitted.  Personally I'd think it unlike that a carburettor is suddenly at fault.  So if you still have the fault, I'd not touch anything on those for the time being, aside from checking and cleaning each filter in the fuel pipe's banjo connection.  If all is well there I'd go on to check the ignition timing.  

I'll let you breeze through the above checks, before boring you with others. But I hope it's helpful, and again I apologise if I'm explaining something that you were perfectly aware of.

Pete.    

 

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Gordon, Did you solve it? We have been through just about every simple fault that exists. All easy to check but difficult to find if happening at the same time. Or one after the other. The great thing is all cheap and easy to fix. So here’s our list......

1. New plugs either faulty of fouled possibly due to one of the following

2 front carb overflowing, needle valve stuck

3 back carb dry needle valve stuck the other way

4 coil slowly dying! Quite possibly the cause of fouled plugs

Good luck JJC

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Hi Gordon, what carbs are you running, if strombergs then you could have a split diaphragm, or two even.

Chris

Edited by ChrisR-4A
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I had an identical experience when bringing the 4A from Melbourne to home in Canberra. Had run beautifully for about 350 miles then ran like a dog for the last hundred after a fuel fill at Yass (about 80-90miles).

When I got home I was able to find a nice dose of water in the tank and in the fuel bowl it has up in the engine compartment. When I did the total refurbishment I also found a lot of rust and crud in the tank that could shift to cover the fuel outlet from the tank, especially when the fuel level was low. I guess when the tank was fuller it could swish past the outlet more easily.

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Hello Gordon

Before fiddling about under the bonnet I suggest that it is likely to be the fuel. Last year two of us filled up at the same supermarket in Wales and both of us experienced both cars running terribly afterwards. Once the fuel level had gone down and we were able to fill up with fresh fuel the problem went away. My 4A will run on bog standard 95 octane without any additives (it had valve seats fitted nearly 30 years ago) but on this occasion there was something wrong with the fuel.

Keith

Edited by keith1948
correction
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Hi all...thx so much for your help. I wish I'd checked the page in past few days but thought I had switched on the bit that tells you when someone adds to the thread. Hence, from Pete's (BFG) incredibly helpful note down, I've only just pocked up all your messages and am now going through all with fine tooth comb :-)  And, yes, Pete, I really am a novice and guess this problem is pay back for me getting the car first before spending a year or so apprenticeship to know enough in order to maintain the car to a large extent. But this gorgeous Valencia Blue baby was just staring at me with those big headlight eyes!

Ok so yesterday I had my first go under the bonnet. I removed the glass petrol bowl adjacent to the fuel pump and cleared out all old sediment. I also pulled away the circular gauze filter above the glass and checked/cleaned that but it was in pretty good nick. All the while there was a steady flow of petrol cascading from the head into a bowl under the car until I re-attached the gauze, the rubber seal and the glass cup and tightened below. There's also a lever under the fuel pump which when pulled up appeared to blow air into the glass bowl and force any remaining sediment out, which it duly did, albeit only a small particle or two. I also checked the 4 spark plugs because, exactly in line with Pete's note, my gut feel is that the issue is somewhere in the engine. The one nearest the windscreen seemed quite covered in grime compared to the other 3 and the screw area was discoloured a bit like a light bulb screw section when a bulb has blown. I carefully sanded the top of each plug (mainly the upper and lower parts of the gap) and cleaned all 4 plugs before replacing,

I've never had bother starting her up and left her to tick over for a while, which didn't;t seem too bad. there was the usual vibration while the choke was out and things warmed up. The main engine block does though seem to vibrate more than I remember previously. I then carefully pressed the accelerator in neutral and it didn't sound perfect but I could be sure if the problem was still there is bad as it was. So I decided to take her out on a very short run up the road and back. As soon as I accelerated in first gear and then again to go up the gears, it was clear the problem is still there.I really feels like I'm on only 3 cylinders and not 4. She does accelerate but very roughly and sounds like a pre-war car udder g that process. When at a steady speed things  settle but clearly not right. Then, as I slowed down to turn back into driveway, there was this awful knocking under the car, as if the vibration was disturbing the exhaust pipes.

So before reading Pete's note tonight I was about to ask you all if it is indeed possible for a spark plug to "go" just like that and , if so, would I get the sudden mis-fire/back-fire that I experienced when leaving the garage those few days ago? I"ll now try Pete's tips on checking the spark plugs. Just hope that, if one of these is the culprit, that I haven';t damaged the engine or the timing by taking her out for these one or two very short test runs or by accelerating the engine in neutral. I can't thank you all enough for your time and thoughts in helping me.

Gordon  

 

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Hi Gordon,

up till 2 years ago I was a fan of NGK spark plugs. Then , over a few month period I found them going stale after apprx 500-1000 miles.

I now use Champion L87 and they last a great deal longer.

So yes, they can go off just like that.

Roger

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On 10/19/2019 at 4:28 PM, ChrisR-4A said:

Hi Gordon, what carbs are you running, if strombergs then you could have a split diaphragm, or two even.

Chris

Wow Chris ..what an absolute beauty you have. Love the red. thx for this thought. I admit to being a novice here so thought it best to send you a photo of the carbs, which I hope will tell you at least what ones I've got

 

On 10/16/2019 at 10:49 PM, Malbaby said:

Do you have a fuel filter between the pump and the carbs?

No Chris...not any addy'l in-line filter if that's what you mean. just the copper piping and a couple of rubber linkage points. But I;'m hoping I may have now solved this issue. See my reply to Pete. Thanks v much for your input. G

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47 minutes ago, RogerH said:

Hi Gordon,

up till 2 years ago I was a fan of NGK spark plugs. Then , over a few month period I found them going stale after apprx 500-1000 miles.

I now use Champion L87 and they last a great deal longer.

So yes, they can go off just like that.

Roger

Aha...well that all starts to make sense Roger thanks. See my reply to Pete coming up now. G

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On 10/16/2019 at 1:43 PM, Bfg said:

I suspect the timing of this new dilemma is coincidental to adding fresh fuel., not least because unless you've drawn in water with your fuel - I don't associate backfires with fuel  but rather ignition. And tick-over vibration most often relates to just one or two cylinders not firing,  something inside breaking or jumping adjustment, or an engine mount not being secure  ..whereas generic fuel problems tend to effect all cylinders.  Because  'something inside breaking or jumping adjustment '  is horribly pessimistic, and in any case often accompanied by odd noises from inside the engine (even at tick over) - my approach would be to start off by checking the HT leads and spark plugs.   

Indeed with any such mystery - I remind myself of the basic workings of an internal combustion engines, and systematically check (..but unless very obviously wrong - not adjust) those.   Not knowing exactly how " bit of a novice under bonnet"  you are - I'll explain, but my please accept my apologies if I'm teaching grandma to blow an egg.  

The basics are  1. spark,  2. fuel,  3. timing (of both ignition and and valve opening), and 4. compression.  And each of these need to be roughly close to tolerance for each cylinder.  And 'the process'  is one of elimination. ie. if you check something works fine ..then you can eliminate it from being the fault.   I've numbered ' the basics' in order of being most commonly at fault on an engine which was previously running normally.    

So, if in your situation, having already thought through the fuel issues, I would start by first checking the HT lead on each plug.   So, start the engine and when warm enough to have a steady slow tick-over -  pull the HT lead off just one plug at a time (wearing rubber gloves or with rubber handled grips / pliers - to save you getting a high voltage shock)  ..and listening to hear for a difference in engine note.   If, when you pull a HT lead cap off, there is no difference in engine speed then that plug or lead is faulty.  

Even if that doesn't identify the issue,  because it's a quick job to do, and so quickly things to eliminate - I'd move on to systematically removing each plug to check its gap and condition.  At the same time you'll be visually checking the condition of each HT lead and cap - for cracks in the insulation, security of the cap onto the lead, and for corrosion, and to check for a positive lock of the cap onto the spark plug.  Also for any chafing of the lead itself along its whole length.  

While each plug is out, check its spark by refitting its cap and resting the threaded part of the plug against the cast iron cylinder head. When turning the engine over you're looking for a small but sharp, bluish spark across its electrodes.  NB. This doesn't check the sparkplug as much as the HT leads, because a spark plug can work (just OK) at tick over but falter when engine revs are applied.  Having said that, a big whitish coloured spark is likely to be faulty spark plug.  Substitution with a set of known-to-be-good plugs, set to the right gap, is the easiest way to eliminate those from the list of suspects.   

If the spark isn't good on each plug - then go one step up-line and check the points. The contact breaker points gap should be something like 15 thou - which is much the same as ordinary copy paper folded three or four times.  Prise the contacts' gap open with a small screwdriver to see if they are clean and bright, or whether they are dark and pitted. If it looks fine then don't touch or adjust things.  When turning the engine over with the cap off - the points gap's spark should be a barely visible bluish crackle, not a big spark which usually indicates a faulty condenser.  Also feel the distributor to ensure it's clamped securely to the engine block, so it doesn't turn.  Carefully also visually check the distributor cap for cracks and cleanliness. Either might be a path to loose your spark through.  Also check the HT lead between the coil and the distributor and it's connections, as well as the small wire feeding power to the points.  

If all that checks out as fine - great you can eliminate 'spark'  from the list of being the potential fault. 

From the photograph I see you have fuel in the bowl.  Undo the clip to drop that glass and see and smell the petrol is fresh and not contaminated with water or debris from the almost empty fuel tank. There should be a fine gauze filter on the underside of the aluminium housing.  Assuming the fuel and filter is clean then carefully refit the glass, taking care to feel that it sits flat on its seal before the clip is refitted.  Personally I'd think it unlike that a carburettor is suddenly at fault.  So if you still have the fault, I'd not touch anything on those for the time being, aside from checking and cleaning each filter in the fuel pipe's banjo connection.  If all is well there I'd go on to check the ignition timing.  

I'll let you breeze through the above checks, before boring you with others. But I hope it's helpful, and again I apologise if I'm explaining something that you were perfectly aware of.

Pete.    

 

Ok Pete...I've just been in the garage with rubber gloves and done exactly what you instructed. Started the car and left it until running with small amount of choke and then pulled out HT leads one by one. In all cases bar one the engine went down a tone and stuttered more, but with the second plug away from screen there was no distinct change in engine tone. I then turned engine off and swapped this plug with the one nearest the windscreen and tested again, only to find the engine not changing when taking the first HT head off this time, albeit still trying to give me a shock or two from the lead itself !! So I believe that spark plug might be the culprit (and not the HT leads themselves), the plugs are made in France with BP6H on one side and NGK on the other. I'll buy a replacement tomorrow (probably will replace all 4 based upon the thoughts of others) and will update you tomorrow eve. Here's hoping !! GJI

 

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