Technical Very frustrating engine cut out !

[Simon1234]

I’m battling with a engine cut out problem.
so, I run a Fiat 500L 1970 with a 126 650cc engine. The car starts no problems, runs no problems until I stop for a while. Then when I re start the car starts, pulls away and starts to splutter. The engine nearly stops just ticks over or sometimes stops.
I have been down the line of thinking that the car was running out of fuel ( as the clear filter seems to empty ), so I replaced the fuel pump.
no luck the problem persists

What should I do next

any assistance would be appreciated

 

[F30Msport]

sounds like the same issue i'm having. I still need to figure it out:

Fuel system (filters, etc) | FIAT 500 (Classic)

So yesterday the 500 seemed to be struggling to get fuel on a ride around the block. Seems fine at idle, but not going down the road where it bucked and sputtered. I stopped and gave it a second, then made it back to the house with little drama. I've searched and had trouble finding clarity on...

www.fiatforum.com

 

[ClassicFiat500]

Try cleaning out the filter in the fuel tank, carefully removing the float assembly (take a photo of the connections) inside the tank you will find a mesh filter, mine was quite gunged up. You say you have a clear plastic filter, REMOVE IT, it has no use & they can catch fire too easy.
Best of luck

 

[Simon1234]

Hi
Thank you for your reply. Today I’m going to clean out the carburettor and check the float for any crack. Although, I’m more convinced it could be an electrical issue that occurs when the car is hot.
So, it’s also time to check out the; points, plugs, caps, leads, distributor, and coil ….. wish me luck.

Just a note to anyone else who has a 126 (650cc) engine in their little old 500.
The carburettor on the 650 has a return pipe outlet on the top that faces back towards the rear seats. This is often blanked off with a small piece if fuel pipe capped off, (usually screw and jubilee clip).
Because it’s not easy to see or access it’s forgotten about.
Mine was the cause of petrol stink in the car, as it was weeping.
So I also investigated the best way to use/resolve this outlet. Through must searching and chatting a very experienced Italian mechanic simply stated to me that the car would never run properly if I didn’t return the pipe to the petrol source (ie the pipe from the tank in the engine bay). With a 6mm brass “T”, thank you internet ! I installed this option. This apparently relieves the carburettor of the pressure build up for smooth running - so I did photo attached, and it does plus no nasty petrol smell



thought I’d share, I’m new to this site so the above has probably been posted 1000 times

Re; latest trouble I will come back with results

 

[Simon1234]

Try cleaning out the filter in the fuel tank, carefully removing the float assembly (take a photo of the connections) inside the tank you will find a mesh filter, mine was quite gunged up. You say you have a clear plastic filter, REMOVE IT, it has no use & they can catch fire too easy.
Best of luck

Thank you I will add that to my list
I have heard much about the fuel filter I have ordered a metal/glass one, I know it’s of no use but for some reason it’s assuring to have it there

 

[Simon1234]

Fuel filter in petrol tank cleaned - very mucky indeed

 

[ClassicFiat500]

Your filter residue looks as black as your coffee. I tried a glass & metal filter but i couldnt seem to obtain a good seal between the glass and the casing, then I read how many 500s went up in smoke caused by the filter leaking onto the alternator or dynamo, I agree its a good way to see if there is a flow of fuel. Shame nobody makes a good safe see through section of strong glass tube to fit into the fuel pipe at the engine end.

 

[Toshi 975]

Hi
Thank you for your reply. Today I’m going to clean out the carburettor and check the float for any crack. Although, I’m more convinced it could be an electrical issue that occurs when the car is hot.
So, it’s also time to check out the; points, plugs, caps, leads, distributor, and coil ….. wish me luck.

Just a note to anyone else who has a 126 (650cc) engine in their little old 500.
The carburettor on the 650 has a return pipe outlet on the top that faces back towards the rear seats. This is often blanked off with a small piece if fuel pipe capped off, (usually screw and jubilee clip).
Because it’s not easy to see or access it’s forgotten about.
Mine was the cause of petrol stink in the car, as it was weeping.
So I also investigated the best way to use/resolve this outlet. Through must searching and chatting a very experienced Italian mechanic simply stated to me that the car would never run properly if I didn’t return the pipe to the petrol source (ie the pipe from the tank in the engine bay). With a 6mm brass “T”, thank you internet ! I installed this option. This apparently relieves the carburettor of the pressure build up for smooth running - so I did photo attached, and it does plus no nasty petrol smell

View attachment 392453

thought I’d share, I’m new to this site so the above has probably been posted 1000 times

Re; latest trouble I will come back with results

I makes me shudder every time I see a plastic filter in that position ‘nough said.
In your list of electrical components you have missed out the most likely suspect , the condenser. Any owner running standard ignition should carry at least one spare in their car.
I would have thought that your very experienced Italian mechanic would have been aware of the millions of Fiat 500 cars that ran fine on the original 26IMB carb that is almost identical to the 28IMB that you have but has no return pipe outlet.
however I see you have a late 126 engine where the carb has a solenoid cut off device. I assume that is functioning properly?

 

[the hobbler]

I makes me shudder every time I see a plastic filter in that position ‘nough said.
In your list of electrical components you have missed out the most likely suspect , the condenser. Any owner running standard ignition should carry at least one spare in their car.
I would have thought that your very experienced Italian mechanic would have been aware of the millions of Fiat 500 cars that ran fine on the original 26IMB carb that is almost identical to the 28IMB that you have but has no return pipe outlet.
however I see you have a late 126 engine where the carb has a solenoid cut off device. I assume that is functioning properly?

As David (Toshi) has mentioned, remove that fuel filter between the pump and the carb--it is NOT NEEDED! You have 3 filters in the system already--tank-unit, top of pump and top of carb. I would be tempted to try an ordibary idle jet, and do away with the 'electronic' one---if that is sticking shut, the engine will not re-start. Condensers---modern condensers are made very cheaply, plus they are in a position on the distributor where they get very hot, and they don't like heat. My suggestion is that you get one of 'Swiftunes' "competition" condensers (SW.1G-SS). They are (a) designed for classic racing care where the original ignition system has to be retained (even Ford GT40s) and, (b) they have 2 long leads on them, 1 x feed and 1 x earth--this allows you to fit the condenser up by the coil, away from the heat of the engine's 'cooling' air.

 

[F30Msport]

Is cleaning out the filter in the gas tank pretty straight forward? What do you clean it with?

Should I disconnect the battery before attempting this?

 

[the hobbler]

Is cleaning out the filter in the gas tank pretty straight forward? What do you clean it with?

Should I disconnect the battery before attempting this?

You could use petrol, thinners etc and a small brush. If the tank is that dirty, it might be worthwhile taking the tank out and having it proffesionally cleaned out---most radiator repair businesses can carry out that sort of job. As to disconnecting the battery--always a wise move!

 

[F30Msport]

Here's what it looks like right out of the tank. Seems pretty clean, I think.

 

[F30Msport]

Car is running well again, but I doubt that was the final remedy. Next onto the carb I guess.

 

[Simon1234]

Your filter residue looks as black as your coffee. I tried a glass & metal filter but i couldnt seem to obtain a good seal between the glass and the casing, then I read how many 500s went up in smoke caused by the filter leaking onto the alternator or dynamo, I agree its a good way to see if there is a flow of fuel. Shame nobody makes a good safe see through section of strong glass tube to fit into the fuel pipe at the engine end.

Hi
thanks for reply - ive now removed the filter, just to see if it was contributing to the problem

 

[Simon1234]

I makes me shudder every time I see a plastic filter in that position ‘nough said.
In your list of electrical components you have missed out the most likely suspect , the condenser. Any owner running standard ignition should carry at least one spare in their car.
I would have thought that your very experienced Italian mechanic would have been aware of the millions of Fiat 500 cars that ran fine on the original 26IMB carb that is almost identical to the 28IMB that you have but has no return pipe outlet.
however I see you have a late 126 engine where the carb has a solenoid cut off device. I assume that is functioning properly?

Hi Toshi
Many thanks for the reply
unfortunately, the “frustrating cutting out”, is a new problem. The smell of petrol was the old problem.
The filter is now history.
Having spent a most enjoyable day carrying out all the jobs from front to back the car still is cutting out when hot. So today I’m replacing the condenser as you recommended, fingers crossed if that doesn’t work then I’ll replace the solenoid

 

[Simon1234]

As David (Toshi) has mentioned, remove that fuel filter between the pump and the carb--it is NOT NEEDED! You have 3 filters in the system already--tank-unit, top of pump and top of carb. I would be tempted to try an ordibary idle jet, and do away with the 'electronic' one---if that is sticking shut, the engine will not re-start. Condensers---modern condensers are made very cheaply, plus they are in a position on the distributor where they get very hot, and they don't like heat. My suggestion is that you get one of 'Swiftunes' "competition" condensers (SW.1G-SS). They are (a) designed for classic racing care where the original ignition system has to be retained (even Ford GT40s) and, (b) they have 2 long leads on them, 1 x feed and 1 x earth--this allows you to fit the condenser up by the coil, away from the heat of the engine's 'cooling' air.

Many thanks for the location and product suggestion.

 

[Simon1234]

Your filter residue looks as black as your coffee. I tried a glass & metal filter but i couldnt seem to obtain a good seal between the glass and the casing, then I read how many 500s went up in smoke caused by the filter leaking onto the alternator or dynamo, I agree its a good way to see if there is a flow of fuel. Shame nobody makes a good safe see through section of strong glass tube to fit into the fuel pipe at the engine end.

Hi
Thanks for the reply, I have now ditched the filter all together. The overwhelming advice here is remove it so I have.
Yep, that petrol filter was very dirty. I don’t think it’s ever been cleaned.

New question: I don’t know the exact colour code or colour name of my car and I noticed your 500 is the same colour. And ideas?
thanks.

 

[Simon1234]

Morning
Having replaced the coil and the problem disappeared,

I had a local garage test the voltage and it read between 12.3v and 22.7v
i am no expert but that is a bit on the high side ?

I have ordered a replacement Voltage regulator from Ricambio, but would like the best quality any suggestions?

 

[fiat500]

Morning
Having replaced the coil and the problem disappeared,

I had a local garage test the voltage and it read between 12.3v and 22.7v
i am no expert but that is a bit on the high side ?

I have ordered a replacement Voltage regulator from Ricambio, but would like the best quality any suggestions?

...it's very much on the high side at 22.7; I wouldn't use it until you change the voltage regulator I
(I assume you have a dynamo)..
If you don't mind the appearance of it, get one of the electronic versions.

 

[lazylobster]

...it's very much on the high side at 22.7; I wouldn't use it until you change the voltage regulator I
(I assume you have a dynamo)..
If you don't mind the appearance of it, get one of the electronic versions.

22.7, seems way too high. Give the engine some revs, 2 - 3000 RPM (by ear) and whack a meter on your battery terminals. From memory, the max should be 14.8v or below, if higher this will cook your battery over time and you'll need a replacement. The electronic one is the way to go. You can mount the old mechanical cover over the top if you still want that original look.