Technical Engine not running smoothly

[jezashton]

Hi everyone,

A little bit of introduction: I have one of the last RHD Fiat 500s - registered in January 1973. I’ve owned it since 1992 when it was in a complete state: a lot of corrosion and no engine/gearbox. About 10 years later, with little progress made, I had a bodyshop weld in the new panels and paint it in what I believe was the original colour, Tahiti yellow. Again, years passed with no progress until last year I decided it was time to sort it out and so I paid a Fiat 500 specialist to fit a reconditioned engine I’d purchased a few years before plus sort the electrics, brakes, etc.. basically getting it to the point where it passed an MOT leaving me with the easier finishing off jobs like trim.

The engine seems really sweet, but I’ve had issues with it not always running smoothly and I was hoping for some thoughts on what the possible reasons could be. This is the first few miles the engine has driven and it’s just sat around for years so it doesn’t surprise me it needs some tweaking to get it running nicely.

• Generally it starts really nicely, even if it’s had a few weeks since it last ran.
• The first thing that happened was that on a short drive it lost power and had to limp home, luckily it was a short drive and it was nearby to home. After a few minutes it was fine again.
• Then another time, I reversed it out the garage and it didn’t have enough power to reverse up the driveway which is on a relatively gentle incline. It wouldn’t rev and applying the throttle just caused some major backfires. I left it running for about 30 minutes and suddenly notice an audible change in the engine note and it was fine.
• Today I took it for a drive and it’s just a bit spluttery all the time. I generally could rev the engine through the lumpiness but it wasn’t great. It also wouldn’t hold its revs when stationary and idling at traffic lights. I needed to keep applying throttle to keep it going.
• I stopped the engine halfway through the journey and had a slight problem getting it started again. It didn’t need much starter motor to get it started but again wouldn’t hold the revs so wouldn’t stay idling and took a few attempts before it managed to stay running.

I’m not an expert at all with engines and will be relying on finding a good garage to help me maintain it, and I’ll probably be wanting help from a garage to sort out this issue. To that end, could anyone recommend a mechanic who would have some experience of this engine in the Lichfield/Burton upon Trent area of East Staffordshire who I could use to get it running nicely and for routine maintenance?

Thanks for any advice in advance,

Jez

 

[RDS]

Hi everyone,

A little bit of introduction: I have one of the last RHD Fiat 500s - registered in January 1973. I’ve owned it since 1992 when it was in a complete state: a lot of corrosion and no engine/gearbox. About 10 years later, with little progress made, I had a bodyshop weld in the new panels and paint it in what I believe was the original colour, Tahiti yellow. Again, years passed with no progress until last year I decided it was time to sort it out and so I paid a Fiat 500 specialist to fit a reconditioned engine I’d purchased a few years before plus sort the electrics, brakes, etc.. basically getting it to the point where it passed an MOT leaving me with the easier finishing off jobs like trim.

The engine seems really sweet, but I’ve had issues with it not always running smoothly and I was hoping for some thoughts on what the possible reasons could be. This is the first few miles the engine has driven and it’s just sat around for years so it doesn’t surprise me it needs some tweaking to get it running nicely.

• Generally it starts really nicely, even if it’s had a few weeks since it last ran.
• The first thing that happened was that on a short drive it lost power and had to limp home, luckily it was a short drive and it was nearby to home. After a few minutes it was fine again.
• Then another time, I reversed it out the garage and it didn’t have enough power to reverse up the driveway which is on a relatively gentle incline. It wouldn’t rev and applying the throttle just caused some major backfires. I left it running for about 30 minutes and suddenly notice an audible change in the engine note and it was fine.
• Today I took it for a drive and it’s just a bit spluttery all the time. I generally could rev the engine through the lumpiness but it wasn’t great. It also wouldn’t hold its revs when stationary and idling at traffic lights. I needed to keep applying throttle to keep it going.
• I stopped the engine halfway through the journey and had a slight problem getting it started again. It didn’t need much starter motor to get it started but again wouldn’t hold the revs so wouldn’t stay idling and took a few attempts before it managed to stay running.

I’m not an expert at all with engines and will be relying on finding a good garage to help me maintain it, and I’ll probably be wanting help from a garage to sort out this issue. To that end, could anyone recommend a mechanic who would have some experience of this engine in the Lichfield/Burton upon Trent area of East Staffordshire who I could use to get it running nicely and for routine maintenance?

Thanks for any advice in advance,

Jez

Hello Jez

Did you sort this?

Have you checked whether your distributor is secure and ignition timing correct?

Cheers

Rds

 

[jezashton]

Hello Jez

Did you sort this?

Have you checked whether your distributor is secure and ignition timing correct?

Cheers

Rds

Hi,

No I haven't resolved it yet. I was hoping for a garage recommendation most of all, I'd really like to find somewhere fairly local that has experiecne of this engine in particular.

I will check the distributor cap is secure, how would I check the ignition timing - and would that be as sporadic as I've described?

Thanks, Jez

 

[ClassicFiat500]

Hi,

No I haven't resolved it yet. I was hoping for a garage recommendation most of all, I'd really like to find somewhere fairly local that has experiecne of this engine in particular.

I will check the distributor cap is secure, how would I check the ignition timing - and would that be as sporadic as I've described?

Thanks, Jez

Hi which part of the country are you based in? I had encountered similar problems like you with little knowledge of such a small engine unlike a 4 or 6 of even an 8 cylinder where you don’t notice the odd misfire in fact with a V8 they just plod on regardless of all their ancillaries breaking down, it seems with aFiat 500 everything has to be set up 100% correct for it to run smoothly. I finished up hiring someone with a trailer to take mine to Bicester, and even after spending £5000 on an engine out job and brake overhaul within 6 months I started having recurring problems. I really envy people on the forum like The Hobbler & Toshi (plus others on the forum) who know these cars inside out & back to front, they can strip & rebuild their cars with their eys closed. So any advise they give is a godsend. The average garage now doesn’t even know what a carburettor is.

 

[ClassicFiat500]

Hi which part of the country are you based in? I had encountered similar problems like you with little knowledge of such a small engine unlike a 4 or 6 of even an 8 cylinder where you don’t notice the odd misfire in fact with a V8 they just plod on regardless of all their ancillaries breaking down, it seems with aFiat 500 everything has to be set up 100% correct for it to run smoothly. I finished up hiring someone with a trailer to take mine to Bicester, and even after spending £5000 on an engine out job and brake overhaul within 6 months I started having recurring problems. I really envy people on the forum like The Hobbler & Toshi (plus others on the forum) who know these cars inside out & back to front, they can strip & rebuild their cars with their eys closed. So any advise they give is a godsend. The average garage now doesn’t even know what a carburettor is.

Hi again Jez, just read your 1st feed and noticed at the end you live in Burton upon Trent area. I would persevere with asking on the forum if they know anyone in your area. Your certainly looking in the right place for help, I know someone will respond. Best of luck & don't give up on it.

 

[the hobbler]

Hi again Jez, just read your 1st feed and noticed at the end you live in Burton upon Trent area. I would persevere with asking on the forum if they know anyone in your area. Your certainly looking in the right place for help, I know someone will respond. Best of luck & don't give up on it.

The nearest garage that I can suggest to you is Motobambino who are at Carnforth (junction 33 on the M6. Mark is very well versed in the restoration of the 500, as well as being a really good guy to deal with. Motobambino have a web-site with their phone number on it. Another garage who are also 500 experts is Middle Barton Garage, Oxfordshire

Hi again Jez, just read your 1st feed and noticed at the end you live in Burton upon Trent area. I would persevere with asking on the forum if they know anyone in your area. Your certainly looking in the right place for help, I know someone will respond. Best of luck & don't give up on it.

Based where you are, I would suggest a couple of garages---Motobambino who are at Carnforth (junc 33 M6) or Middle Barton Garage (Junc 10 M40) Both these garages are experts in 500s. Sadly, to the best of my knowledge, there is nobody in your actual area. Yes, you will have to trail/deliver your car to their premises, but having worked in garages most of my working life (including helping to set-up 2 M/Benz garages from scratch) from experience I know that these intermittant problems are the hardest to resolve---I wish that i had been given a fiver by every customer who came in on the appointed day and said "but it is not doing it now!" Both the above garages have web-sites with their phone number and addresses on them---Mark at Motobambino and Tony at Middle Barton

 

[FR85]

Before you go down the route of garages, tell us what your distributor is like.
Identify if you have points and condenser (original set up) or if it has an electronic set up after the rebuild.
Your symptoms I have experienced, my electronic ignition failed recently, couldn't rev high with barely any power but it would idle alright-ish.
Popped in points and a condenser and we were back in business.
I have seen from other users that points and condensers don't do well with heat which is unfortunate due to the distributors location at the exhaust and thermostat outlet so again from what you described, a short drive and lack of power, this set up too could be breaking down and when warm can cause hard starts.
Hard starts from hot and under performance can also be related to valve clearance but if it comes to it we'll get to that.
Try and identify your set up and report back.....

 

[jezashton]

Before you go down the route of garages, tell us what your distributor is like.
Identify if you have points and condenser (original set up) or if it has an electronic set up after the rebuild.
Your symptoms I have experienced, my electronic ignition failed recently, couldn't rev high with barely any power but it would idle alright-ish.
Popped in points and a condenser and we were back in business.
I have seen from other users that points and condensers don't do well with heat which is unfortunate due to the distributors location at the exhaust and thermostat outlet so again from what you described, a short drive and lack of power, this set up too could be breaking down and when warm can cause hard starts.
Hard starts from hot and under performance can also be related to valve clearance but if it comes to it we'll get to that.
Try and identify your set up and report back.....

Hi all,

Thanks for the help. I’ve thought about Middle Barton but like you say, it’s quite a drive so wondered if I could find someone nearer, so any more recommendations would be appreciated.

I’ve attached some photos of the distributor, so hopefully they help you see what you need.

Thanks, Jez

 

[FR85]

Hi all,

Thanks for the help. I’ve thought about Middle Barton but like you say, it’s quite a drive so wondered if I could find someone nearer, so any more recommendations would be appreciated.

I’ve attached some photos of the distributor, so hopefully they help you see what you need.

Thanks, Jez

You are still on points and a condenser which are prone problems from heat rising from the exhaust. There is normally a heat shield just above the exhaust but where this screws to has been butchered to fit in the exhaust. I'd have a look at changing the points, condenser, coil and spark plug leads and see how you get on. Then have a look at timing ect if that doesn't cure the issue.
It to me sounds like a fall down in spark.

If this solves it, look at moving the coil and condenser over to the other side of the engine bay where it's cooler, that's next on my list.

 

[ClassicFiat500]

Hi all,

Thanks for the help. I’ve thought about Middle Barton but like you say, it’s quite a drive so wondered if I could find someone nearer, so any more recommendations would be appreciated.

I’ve attached some photos of the distributor, so hopefully they help you see what you need.

Thanks, Jez

Hi Jez as I said earlier my knowledge of the mechanics sounds a bit like you, thats the reason I looked for a garage that knew what a Fiat 500 engine looked like. There are not many by me either. When I asked Middle Barton Garage they recommended a guy from near Bicester to pick up and return my car, he was very good and charged me I think about £80 from Woburn to Bicester. With Middle Barton Garage they appeared to be good & very knowledgeable, but I was a little disappointed with them regarding the fact they rebuilt the steering box which now has a permanent drip, also I still have an annoying leak from under the engine which was one of the reasons the car went to them, but the worst problem was the fact I have a webber DCO40 the left one of the retaining bolts off & the other three were very loose causing a massive air leak. They did other work like a brake & suspension rebuild & corrected the Oil cooler position which was too low.When I mentioned about the leaks they said they would put it right with no problem but it meant another trailer journey again to Bicester at another £80 each way. So the moral of it, is to find someone locally even if you can find an older retired mechanic who may come to you. if you ask in your local garages & explain the problem, most garages know of older retired mechanics. Bye the way the work at MBG cost me £5k plus transport there & back. You will find someone locally but I would be reluctant to send it too far away as I did. (if you have a look on my threads you will see the problems i have encountered.) Best of luck Barry Classicfiat500

 

[ClassicFiat500]

Hi Jez as I said earlier my knowledge of the mechanics sounds a bit like you, thats the reason I looked for a garage that knew what a Fiat 500 engine looked like. There are not many by me either. When I asked Middle Barton Garage they recommended a guy from near Bicester to pick up and return my car, he was very good and charged me I think about £80 from Woburn to Bicester. With Middle Barton Garage they appeared to be good & very knowledgeable, but I was a little disappointed with them regarding the fact they rebuilt the steering box which now has a permanent drip, also I still have an annoying leak from under the engine which was one of the reasons the car went to them, but the worst problem was the fact I have a webber DCO40 the left one of the retaining bolts off & the other three were very loose causing a massive air leak. They did other work like a brake & suspension rebuild & corrected the Oil cooler position which was too low.When I mentioned about the leaks they said they would put it right with no problem but it meant another trailer journey again to Bicester at another £80 each way. So the moral of it, is to find someone locally even if you can find an older retired mechanic who may come to you. if you ask in your local garages & explain the problem, most garages know of older retired mechanics. Bye the way the work at MBG cost me £5k plus transport there & back. You will find someone locally but I would be reluctant to send it too far away as I did. (if you have a look on my threads you will see the problems i have encountered.) Best of luck Barry Classicfiat500

 

[the hobbler]

You are still on points and a condenser which are prone problems from heat rising from the exhaust. There is normally a heat shield just above the exhaust but where this screws to has been butchered to fit in the exhaust. I'd have a look at changing the points, condenser, coil and spark plug leads and see how you get on. Then have a look at timing ect if that doesn't cure the issue.
It to me sounds like a fall down in spark.

If this solves it, look at moving the coil and condenser over to the other side of the engine bay where it's cooler, that's next on my list.

An alternative condenser that I reccomend is the unit sold by "Swiftune". This condenser is built to high standard for competition cars that, due to the rules, have to use their original ignition system. The "Swiftune competition condenser" has long leads (both earth and feed) so can be situated up by the coil and away from the hot 'cooling' air coming off th engine. The points don't normally get affected by the heat, but modern, cheaply built, condenders do. Using one of these condensers will mean that the coil can stay on the o/s of the engine bay and you can mount the condenser up close to it away from the heat.

 

[Mark126]

I can't help noticing the damage to the the HT lead in the second picture you've uploaded. I recently had a lot of trouble with my 126 which was displaying all the symptoms you list, it turned out the HT lead from the coil to the distributor had a small crack in it, and when replaced the car ran fine again. Maybe it's worth changing your leads as they aren't expensive and will rule that out as a potential cause.

 

[jezashton]

You are still on points and a condenser which are prone problems from heat rising from the exhaust. There is normally a heat shield just above the exhaust but where this screws to has been butchered to fit in the exhaust. I'd have a look at changing the points, condenser, coil and spark plug leads and see how you get on. Then have a look at timing ect if that doesn't cure the issue.
It to me sounds like a fall down in spark.

If this solves it, look at moving the coil and condenser over to the other side of the engine bay where it's cooler, that's next on my list.

I hate the way it’s been (as you put it) butchered to fit the exhaust. Does anyone have a recommendation for a heat shield that will fit around this exhaust as the one I have is clearly for a different setup, see attachment below?

 

[jezashton]

An alternative condenser that I reccomend is the unit sold by "Swiftune". This condenser is built to high standard for competition cars that, due to the rules, have to use their original ignition system. The "Swiftune competition condenser" has long leads (both earth and feed) so can be situated up by the coil and away from the hot 'cooling' air coming off th engine. The points don't normally get affected by the heat, but modern, cheaply built, condenders do. Using one of these condensers will mean that the coil can stay on the o/s of the engine bay and you can mount the condenser up close to it away from the heat.

Thanks for your comments. Does the Swiftune unit replace the component I’ve circled in blue in the attached photo?

If so, it only has one cable coming out (see other photos) that seems to attach to the body of the distributor and is then also connected across to the coil.

And does it need to be physically mounted to some itching specific or can I attach it near to the coil and what matters is where the two cables are attached?

And is this the correct replacement unit:
https://swiftune.com/parts-shop/ignition/swiftune-competition-condenser.html

 

[jezashton]

I can't help noticing the damage to the the HT lead in the second picture you've uploaded. I recently had a lot of trouble with my 126 which was displaying all the symptoms you list, it turned out the HT lead from the coil to the distributor had a small crack in it, and when replaced the car ran fine again. Maybe it's worth changing your leads as they aren't expensive and will rule that out as a potential cause.

That’s a great spot! The mark that really looks like damage, is actually just some muck on the leads which I’ve cleaned off. They actually look in great condition, but I’m glad you pointed it out.

 

[Toshi 975]

I hate the way it’s been (as you put it) butchered to fit the exhaust. Does anyone have a recommendation for a heat shield that will fit around this exhaust as the one I have is clearly for a different setup, see attachment below?

You have the standard F/L heat shield there but you have a 500R/126 type engine. If you look on the Ricambio web site they lists a 500R heat shield. You are also missing the left hand / near side engine under tray.

 

[the hobbler]

That’s a great spot! The mark that really looks like damage, is actually just some muck on the leads which I’ve cleaned off. They actually look in great condition, but I’m glad you pointed it out.

The factory fitted condenser fits onto the distributor with its one lead going to the points wire (the negative on the coil) and earthing out through the condenser body. With the 'Swiftune' condenser you can mount it up by the coil using one of the coil-bracket securing bolts/nuts. It comes with one lead with a 'O' connecter on it---this is the earth wire and can, again, be secured to one of the coil-bracket bolts/nuts. The other lead has a normal 'female' connector on it---this is the lead to the negative side of the coil. When you remove the condenser from the side of the distributor, put the little screw back in as this helps locate/secure the points 'deck'

 

[jezashton]

The factory fitted condenser fits onto the distributor with its one lead going to the points wire (the negative on the coil) and earthing out through the condenser body. With the 'Swiftune' condenser you can mount it up by the coil using one of the coil-bracket securing bolts/nuts. It comes with one lead with a 'O' connecter on it---this is the earth wire and can, again, be secured to one of the coil-bracket bolts/nuts. The other lead has a normal 'female' connector on it---this is the lead to the negative side of the coil. When you remove the condenser from the side of the distributor, put the little screw back in as this helps locate/secure the points 'deck'

Thanks for all the useful comments

I've bought and installed the Swiftune condenser and mounted it next to the coil. It's all working but unfortunately hasn't resolved the issue.

I'm thinking the next step is to see whether the fuel filter at the petrol tank needs cleaning out. I don't suppose anyone has or has seen a pictorial guide to doing it have they?

Jus a bit more info on the symptoms, because thinking about this I don't think it's related to engine heat as it's worst when I first start the engine and when everything is still cool (despite this I am still sorting out the exhaust heat shield).

• The problem is worst when I first start the engine from cold, and usually will disappear after a few minutes running. At this point I can't rev the engine at all, any attempt to depress the throttle and the engine loses revs and threatens to stall.
• Despite this the engine starts first time every time from cold with very little time turning over the starter motor.
• It seems to have a possible link to the choke being open. After starting the engine, when I get to the point where I can close the choke, the problem has usually gone - but not always.
• I did have one particular bad run which I referenced in the OP. I drove for about 20 minutes and stopped the engine. After about 5 minutes I came back and really struggled to restart the engine, and having restarted it, on the return journey, the engine was at its worst - spluttering constantly and struggling to idle if I stopped at traffic lights.

 

[the hobbler]

Thanks for all the useful comments

I've bought and installed the Swiftune condenser and mounted it next to the coil. It's all working but unfortunately hasn't resolved the issue.

I'm thinking the next step is to see whether the fuel filter at the petrol tank needs cleaning out. I don't suppose anyone has or has seen a pictorial guide to doing it have they?

Jus a bit more info on the symptoms, because thinking about this I don't think it's related to engine heat as it's worst when I first start the engine and when everything is still cool (despite this I am still sorting out the exhaust heat shield).

• The problem is worst when I first start the engine from cold, and usually will disappear after a few minutes running. At this point I can't rev the engine at all, any attempt to depress the throttle and the engine loses revs and threatens to stall.
• Despite this the engine starts first time every time from cold with very little time turning over the starter motor.
• It seems to have a possible link to the choke being open. After starting the engine, when I get to the point where I can close the choke, the problem has usually gone - but not always.
• I did have one particular bad run which I referenced in the OP. I drove for about 20 minutes and stopped the engine. After about 5 minutes I came back and really struggled to restart the engine, and having restarted it, on the return journey, the engine was at its worst - spluttering constantly and struggling to idle if I stopped at traffic lights.

The more I hear, the more I am convinced that it is a carb problem. The standard carb on a 500/126 does not have 'choke' in the correct technical sense. although everybody refers to it as "the choke". It is a "fuel enrichment device"---it might be worthwhile (a) checking that it actually opening and closing properly and (b) that there is nothing inside it fouling it or blocking it internally---it is very simple to take apart and rebuild.
With regard to the filter on the tank-unit; it is a simple job to remove the small nuts holding the tank-unit onto the tank (mark its position on the sender AND on the tank) then withdrawing the complete unit out. Cleaning the filter is very simple---it is a simple cylindrical filter on the end of the tank-unit. Be careful when you remove the wires on the tank-unit---put a bit of insulation tape around them or a little bit of hose (so nothing goes amiss electrically re petrol fumes)