General Won't start when hot.

[kerryabramson]

Checked and adjusted valve clearance. All okay. I have been running premium gas and will try regular to get it to run cooler. The next fix is wrapping the exhaust, followed by rigging up a fan to blow at the carburator. Any personal recommendations for a really good coil to run with the Hot Spark? Thoughts on wrapping the exhaust or the blower?

 

[Vitesse]

Checked and adjusted valve clearance. All okay. I have been running premium gas and will try regular to get it to run cooler. The next fix is wrapping the exhaust, followed by rigging up a fan to blow at the carburator. Any personal recommendations for a really good coil to run with the Hot Spark? Thoughts on wrapping the exhaust or the blower?

I run a Bosch Blue coil with 123 distributor purely because that's what 123 recommend. As Mattsdad stated earlier in the thread a Flamethrower will suffice.

Then you have to decide if to go with oil filled or Epoxy. Oil filled will run cooler but epoxy is better for vibration or off road use. Given the fact that the coil is mounted on the body of the car rather than the engine itself it's not going to be suffering from a great deal of vibration. Given that I would go with an oil filled flame thrower.

When you have hot restart problems, if you touch the coil is it red hot i.e. Unable to touch or are you able to put you hand on it and leave it there, it should be hot to the touch but not red hot?

Exhaust wrap is a debatable subject. I have it on my exhaust and I know Chris does. As Damian said on the other thread on this subject you are going to get heat leakage through the exhaust onto the cylinder head, it's possible that it could potentially make the engine run hotter as the heat is unable to escape from the exhaust? I was in two minds whether to fit it or not but I thought I would give it a go as I had already bought it.

Installing a fan and putting exhaust wrap on is not really fixing the problem but you are masking it, it is really best to get to the root cause of the issue if you can. I appreciate you have suffered the problem for a longtime now and it is very frustrating.

Alternatively I am sure there will be a lot of volunteers willing to come and help you if you are willing to pay for their air ticket to Hawaii.

Tony

 

[Vitesse]

Oh and another thing is your thermostat flap opening up when the engine is hot?

On exhaust wrap I just found a old post of mine and I forgot I had carried out a little experiment. Without the exhaust wrap and from a cold start and the car just sitting idling it took 10 mins for the thermostat flap to fully open. Doing the same with exhaust wrap fitted it took 30 mins for the flap to open, quite a substantial difference, so it does prove there is a degree of initial heat reduction.

 

[kerryabramson]

Hi Tony. Thank you for your response. You seem to know our little car well. The coil gets very hot during use where you could touch it quickly but never grab it.

It may be important to note that I have no thermostat apparatus or heater hose. The flap by the distributor is permanently open. As you know temperature never gets cold here so I didn't see the harm. Incorrect assumption?

Last weekend I placed a cold gel pack on the carb after it failed to restart and that seemed to decrease the wait time for a successful restart. When she runs, it runs smoothly and strong.

I am going to try the exhaust wrap, then besides a blower for the carb and engine bay I am stumped. A trip to Hawaii may be the least expensive fix and perhaps a good investment if we could lick this problem for good. Aloha Kerry

 

[Vitesse]

Hi Tony. Thank you for your response. You seem to know our little car well. The coil gets very hot during use where you could touch it quickly but never grab it.

It may be important to note that I have no thermostat apparatus or heater hose. The flap by the distributor is permanently open. As you know temperature never gets cold here so I didn't see the harm. Incorrect assumption?

Last weekend I placed a cold gel pack on the carb after it failed to restart and that seemed to decrease the wait time for a successful restart. When she runs, it runs smoothly and strong.

I am going to try the exhaust wrap, then besides a blower for the carb and engine bay I am stumped. A trip to Hawaii may be the least expensive fix and perhaps a good investment if we could lick this problem for good. Aloha Kerry

Hi Kerry I don't think the lack of a thermostat flap or heater hose should make any difference in fact it would probably assist.

I am a worried about the hot coil it doesn't sound right. Reading back on your previous posts I see you are running with a 650cc engine, with an alternator I assume?

Here is a quote from a post on another thread that I posted previously. It seems to be quite a common problem that people over look when installing a 650 engine, so it runs fine initially and then the coil starts to breakdown and overheats and won't produce a decent spark. Once it cools down it will be ok.

Tony

"Are you running the coil from the original 500 engine? One suggestion I have found on another forum is that when changing from a 500 to 650, so by default you are going to go from dynamo to alternator. The output of the alternator charges the Battery to a higher voltage approx 14-15v. The coil from a 500 setup isn't expecting much more than 12v, anything greater then the coil starts to overheat and breakdown. See if your coil is really hot whilst the engine is running. Also measure the LT side of the coil if it is anything higher than about 12.4v it will damage a standard 500 coil. The resolution is to fit a ballast resistor on the positive LT wire to the coil that will reduce the voltage down".

 

[124spiderman]

Aloha. My name is Kerry and I have a 69 Fiat 500 in Hawaii. The car has a rebuilt 650 engine and tranny. I am suffering from the same hot start problem that seems to be getting worse as I contine to track down the problem by spending time and a lot of money on parts. I have a new carb, plugs, wires, fuel pump (and a electric secondary). I do have a Hot Spark ignition with a standard coil so I am intrigued and excited about Mattsdad's suggestion. I was otherwise thinking vapor lock as after I iced the carb, the car restarted (could just be everything cooled off?). I am ready to wrap the exhaust and even rig up a carb fan. Any body have or know how tp cure the problem - it is zapping the pleasure out of my Fiat 500 experience. Kerry[/QUOTE

I think you'll find that Hot Spark is your problem.

 

[124spiderman]

Aloha. My name is Kerry and I have a 69 Fiat 500 in Hawaii. The car has a rebuilt 650 engine and tranny. I am suffering from the same hot start problem that seems to be getting worse as I contine to track down the problem by spending time and a lot of money on parts. I have a new carb, plugs, wires, fuel pump (and a electric secondary). I do have a Hot Spark ignition with a standard coil so I am intrigued and excited about Mattsdad's suggestion. I was otherwise thinking vapor lock as after I iced the carb, the car restarted (could just be everything cooled off?). I am ready to wrap the exhaust and even rig up a carb fan. Any body have or know how tp cure the problem - it is zapping the pleasure out of my Fiat 500 experience. Kerry[/QUOTE

I think you'll find that Hot Spark is your problem.

Hi Kerry check the charge voltage rate, if it's more than 13.6 at 2500rpm (and i'll bet it is) then you've fried the ignition module. Mine did the same.
http://www.hot-spark.com/Troubleshooting.pdf

 

[kerryabramson]

Thank you for your reply and diagnosis. I did read the link provided on Hot Spark problems. I did not have a chance to run the Fiat and put a volt meter on it. I will as soon as I can.

On Saturday I wrapped my exhaust and took the little Fiat out for a run. It idled perfectly for about 20 minutes with the engine hood open. The carb and coil felt relatively cool. I decided to tempt fate and take it for a spin. About 10 minutes into the ride it began to lose power when pulling away from a stop sign and later at a stop light. Just felt like it was about to stall and wasn't pulling at low rpm. Once moving it ran and shifted normally. 5 minutes later it would not pull up my (steep) driveway.

The hood was hot tot the touch. The coil and carb were extremely hot. Withing another 5 minutes the car would crank but would not turn over. I noticed the fuel seem to drain from the filter.

Could this be a failing ignition? It seems to me to be fuel related like vapor lock. It is basically every time I start and try to restart. I would think that if the Hot Spark was the culprit, it would quit and not restart, even when cool. If you are still strongly believing it is the ignition, would you recommend I shift back to points and condenser, get a new HotSpark or a 123?

 

[kerryabramson]

Vitesse,

My coil is not the original one as standard for the 500. The coil has a primary resistance or 3.4 Ohms and a secondary of 9900. I have yet to check the volts while it is running. The coil is a generic one so I am willing to buy a Flamethrower or Bosch Blue to see if the cures my hot start problem. Can't seem to get away from thinking my problem is boiling fuel.... The carb acts like a heat sink when I turn off the engine.

 

[124spiderman]

Thank you for your reply and diagnosis. I did read the link provided on Hot Spark problems. I did not have a chance to run the Fiat and put a volt meter on it. I will as soon as I can.

On Saturday I wrapped my exhaust and took the little Fiat out for a run. It idled perfectly for about 20 minutes with the engine hood open. The carb and coil felt relatively cool. I decided to tempt fate and take it for a spin. About 10 minutes into the ride it began to lose power when pulling away from a stop sign and later at a stop light. Just felt like it was about to stall and wasn't pulling at low rpm. Once moving it ran and shifted normally. 5 minutes later it would not pull up my (steep) driveway.

The hood was hot tot the touch. The coil and carb were extremely hot. Withing another 5 minutes the car would crank but would not turn over. I noticed the fuel seem to drain from the filter.

Could this be a failing ignition? It seems to me to be fuel related like vapor lock. It is basically every time I start and try to restart. I would think that if the Hot Spark was the culprit, it would quit and not restart, even when cool. If you are still strongly believing it is the ignition, would you recommend I shift back to points and condenser, get a new HotSpark or a 123?

As I started this thread I know this is going to sound annoying but it takes less than 30mins to replace the hot spark module with a set of points and condenser. Mine had exactly the same issues as yours. Try that first. I should also mention that mine also had a brand new Marelli coil ( BK2A) and it was found to be faulty when it got hot. Don't take brand new parts for granted.
I wouldn't recommend wrapping exhausts, for one the engine pipes also act as a cooling agent, wrapping only intensifies the heat elsewhere ie the cylinder head and exhausts valves. One must remember that these cars derived from Italy- hot summers and performed generally well in those conditions. I remember as a kid in Italy we used to drive to the beach in the hot Calabrian summers......So heat soak isn't really a problem unless there is some other cooling issues (slipping fan belt, burnt valves, dirty clogged engine fins etc). As far as recommending another type of ignition source I know I'm going to upset a few here but.....If you use your car regularly ie every day or so, yes I would probably recommend electronic ignition BUT if you are like me and drive it only a few days a month or once a week (depending on weather), leave the points. Cars ran fine with them for years. Oh btw, Hot Spark wouldn't honour the 3 year warranty...not happy.

 

[zingercustoms]

I am having an issue similar to this. The engine I just did was a 1959 479 cc..customer wanted more pep so we installed the 540 jug kit and sport cam..with the dellorto 40 carb and electronic ignition. We got it running, drove a few miles a couple times. Got back on second time driving it and turned it off and it would not start. I took off valve cover cap and as it was turned over it was pushing a lot of air. So I did a valve adjustment. Started right up first time. I drove it a few times and then delivered it. The customer drove it a couple times and then it wouldn't start. Let me add that it never would start after these hot cycles even after it cooled down. I picked it up..took me about 10 minutes to adjust valves and, again it started on the first try. It was winter so I would run it inside for 20 minutes every week a couple times a week. Then today I took it into town..drove around at 35 mph for about 30 min. Stopped got gas...started right back up and drove around for another 10 min and stopped for some coff and a snack. Started up no problem. Drove it about 3 miles and this time we were going about 45 mph. Stopped at my brothers house to show him, turned it off. It sat for about ten minutes and when I tried to start it...nothing...let it cool...nothing..blowing hard again out the top of the valve cover when cranked. I am positive it will start right up if I do another valve adjustment. I have the nice electronic ignition mrfiat sells. It was really hot..the valve cover cap burned my finger...my buddy says it has something to do with non hardened valve seats and unleaded gas...but before we rebuilt it it ran fine and I know they weren't using any addatives. He says if the machine shop didn't put hardened seats in then I need to take the head off and have it redone... Any suggestions...?

 

[rusty500]

I realize this is an old thread, but I've been reading through it and am confused/curious about something.

(I have a '70 500L with a 650 conversion that starts easily when cold, runs beautifully when hot, but won't restart when it's hot.)

I'm trying to distinguish between problems that would cause the engine to run poorly when hot versus things that would cause the engine not to start when it's hot. The one that I'm curious about is the coil. I don't understand why a problem with the coil (or anything in the ignition) would be a problem when starting and not when running. If the coil is breaking down from heat, wouldn't that also be a problem when the engine is running?

Thanks.

 

[fiat500]

The two main culprits which seem to recur regularly are:

1: Fuel vaporisation where the fuel has gassified because of the heat from the engine. When stopped for a few minutes this can create a temporary fuel shortage resulting in jittery running for a few seconds after starting or total non-start until the fuel system cools down. Sometimes you need to remove a rubber pipe to allow fuel to push out a fuel lock or even crank the engine until fuel comes out. Obviously patience is better because of the fire risk.
2. The valve clearances are too tight so that when the engine is very hot the gap between the rocker tappet face and the valve stem closes up with heat expansion and keeps the valve very slightly open. This reduces suction of fuel into the engine and compression pressure; resulting in reluctant starting.

Combine the above problems and you could have quite a problem.
There have been problems reported with electrical problems also caused by heat expansion affecting the workings of the coil in particular. When the engine is stopped there is an initial rise in temperature as the impeller is not providing cooling air. In modern cars this is overcome by having an electrical fan which can also run when the car is stopped.

Solutions to the heat problem aren't easily worked out, but checking and adjusting the tappets is easy and is worthwhile doing regularly in any case.

 

[Vitesse]

An ignition coil is basically a step up transformer that converts 12v's on the primary coil to 1000's on the secondary coil to create a spark. They need insulation between the two coils to allow it to work efficiently, older coils were oil filled, newer ones resin. On occasions this insulation will breakdown due to the primary coil being fed with too high a voltage from the battery, hence the output voltage will be much higher and this can cause overheating of the coil and breakdown the insulation inside. Hence the need for a ballast resistor in some cases.

The insulation qualities of the coil is much better at lower temperatures and it will work fine when cooler but once it becomes warmer and the insulation starts to breakdown, it starts to have problems inducing the high voltage in the secondary coil.

As Peter said all engine temperatures will rise after being switched off as the is no air flow on the engine, which is obviously more significant on an air cooled engine, so it can take along time for the coil to return to a cooler temperature if it starting to suffer insulation breakdown.

I have read that sometimes if you tap a coil on the outside with a screwdriver or something when it is cooler and if the engine misfires as a result of this, then it is a sign the insulation is starting to breakdown, but I don't know how true this is?

Tony

 

[rusty500]

Following up on the post from Vitesse quoted below...

This seems to describe my situation. I have a 70 500L with a 126 engine with an alternator. (Haven't run the numbers on the engine yet, so I don't know what year it is.) After reading this post, I checked the voltage on the LT lead to the coil and it was consistently 12.9V. It sounds like that is high enough to damage the coil. Correct

What's the recommended fix? A coil designed for a 126? A ballast resistor? Both?

Being relatively new at this, I would love to get recommendations for specific brands and specifications.

Thanks.

....

Here is a quote from a post on another thread that I posted previously. It seems to be quite a common problem that people over look when installing a 650 engine, so it runs fine initially and then the coil starts to breakdown and overheats and won't produce a decent spark. Once it cools down it will be ok.

Tony

"Are you running the coil from the original 500 engine? One suggestion I have found on another forum is that when changing from a 500 to 650, so by default you are going to go from dynamo to alternator. The output of the alternator charges the Battery to a higher voltage approx 14-15v. The coil from a 500 setup isn't expecting much more than 12v, anything greater then the coil starts to overheat and breakdown. See if your coil is really hot whilst the engine is running. Also measure the LT side of the coil if it is anything higher than about 12.4v it will damage a standard 500 coil. The resolution is to fit a ballast resistor on the positive LT wire to the coil that will reduce the voltage down".

 

[Vitesse]

Hi I wouldn't say 12.9v is excessive, in fact it's is probably just about right.

It doesn't mean the coil isn't faulty though it may still have a problem. Does it get hot after a run? I mean really hot where you can barely touch it.

A decent coil to try is a Bosch Blue 221 119 027.

Tony

 

[Paolo66]

Hi I wouldn't say 12.9v is excessive, in fact it's is probably just about right.

It doesn't mean the coil isn't faulty though it may still have a problem. Does it get hot after a run? I mean really hot where you can barely touch it.

A decent coil to try is a Bosch Blue 221 119 027.

Tony

I've heard these coils mentioned before Tony. Do they really make a difference? Is it due to 3 ohms resistance? Electrics aren't my thing
Damian

 

[fiat500]

I think the confusion is from this quote Tony,
"See if your coil is really hot whilst the engine is running. Also measure the LT side of the coil if it is anything higher than about 12.4v it will damage a standard 500 coil. The resolution is to fit a ballast resistor on the positive LT wire to the coil that will reduce the voltage down"
Rusty500 has an alternator which was the scenario described as being a problem.

 

[the hobbler]

Hi Zingerman;
Which electronic ignition have you fitted? Is it the Pertronix (MR 122), or the '123' system. I find that you have to match the coil with the system, especially as the original coil on the 500 (and early 595cc 126 models) was designed for a Dynamo charging system. If you have fitted the Pertronix system, than I think that you will find that the coil to go with that is the "Pertonix flame-thrower 40,000 volt coil" (NO ballast resister).

 

[rusty500]

Hi I wouldn't say 12.9v is excessive, in fact it's is probably just about right.

It doesn't mean the coil isn't faulty though it may still have a problem. Does it get hot after a run? I mean really hot where you can barely touch it.

It does get really hot, but I'm typically running it in 75F+ weather, so everything in the engine compartment gets too hot to touch. I guess I should see what happens on a cool day.

I think I will try a new coil, but I read somewhere that coils work fine down around 9V, so I'm wondering if I should get both coil and resistor anyway.

Thanks for the coil recommendation, Tony.

--Danny