Technical Starting problems

[Fiat1212]

I have an F model that I hadn't started in 10 years and after putting in fresh fuel, new gas tank, new fuel pump and new fuel lines I cranked it over, but it wouldn't fire. So put in a new coil and regulator and a 123 distributor, I got the same result - cranking but no firing. My spark plugs were wet with fuel. I tested my blue (positive) lead on the coil and I was getting voltage in.
I have no condenser or points to blame since I put in the 123 distributor. I also put in new spark plug cables. So I ran a lead direct from the Positive battery terminal to the positive coil and it started easily and ran well.
So I blamed my blue wire that runs from the 2nd fuse to the positive coil even though it tested very low resistance on the ohm meter. I made a new lead anyway and it showed voltage at the pos coil BUT the car would not start with this new wire.
I ran a direct lead from the battery again and it started up fine.
If I leave the blue lead in place and start with a direct lead from the battery, I find I can take away the direct lead and it will still run and not shut off until I turn the the key off, ( IE shut off the blue lead). If I start with no blue lead and just a direct from the battery the motor will shut off by disconnecting the direct lead.

I have no other quirky electrical problems, except my horn doesn't work. But I don't think those systems share any power. So, what obvious thing am I missing?

 

[bugsymike]

I would check the voltage at the coil when engine cranking, it can be something like a ballast resister supply if you have one or also a fault at the ignition switch killing coil feed when in the cranking position.

 

[smart51]

I'd take a spark plug out and hold the side against the engine while cranking to make sure there is a spark. Have you checked the timing? You say you have fuel. Do you have compression?

 

[Goldnrust]

I think @bugsymike is along the right lines with the idea of voltage drop when cranking.

Clearly you have isolated the problem to be the positive feed to the coil. As you have replaced the wire from the fuse box to the coil, and that has not fixed the problem, it seems logical that the problem lies between that wire and the battery. It could be dirty contacts on the fuse itself, or on the wire that is powering that fuse?

My 500 had sat for many years, and whilst the fuse box initially looked ok, every connection in our and was actually pretty corroded. I had to clean them all up with a wire brush before any of the electrics would come to life. It might be worth doing the same for your car, and maybe that will fix the horn while you’re at it!

 

[Fiat1212]

I would check the voltage at the coil when engine cranking, it can be something like a ballast resister supply if you have one or also a fault at the ignition switch killing coil feed when in the cranking position.

Ballast resistors are always a likely suspect in old cars, but not all old cars use them. I don't think the Fiat 500 has one. I don't see one in the wiring diagram and didn't see one on my car.

 

[Fiat1212]

I'd take a spark plug out and hold the side against the engine while cranking to make sure there is a spark. Have you checked the timing? You say you have fuel. Do you have compression?

I have good compression and timing as it runs very well once started with the direct feed but the spark I didn't check while cranking it over with the original wiring.

 

[Fiat1212]

I think @bugsymike is along the right lines with the idea of voltage drop when cranking.

Clearly you have isolated the problem to be the positive feed to the coil. As you have replaced the wire from the fuse box to the coil, and that has not fixed the problem, it seems logical that the problem lies between that wire and the battery. It could be dirty contacts on the fuse itself, or on the wire that is powering that fuse?

My 500 had sat for many years, and whilst the fuse box initially looked ok, every connection in our and was actually pretty corroded. I had to clean them all up with a wire brush before any of the electrics would come to life. It might be worth doing the same for your car, and maybe that will fix the horn while you’re at it!

Right, I'll compare the intensity of sparks with the original wiring vs the direct lead.

 

[bugsymike]

With just your original blue wire in place, can you put a voltmeter on it and see if you have 12 volts at the coil and then see if it drops as you crank or someone else cranks the engine.
As @Goldnrust mentions fuse connections can get pretty corroded, also modern cheap aluminium fuses give a poor connection when compared with the older brass ones. I have seen headlights suddenly start to work just by turning/revolving a corroded fuse that initially looks OK.
Plus as I mentioned at the start of thread, the ignition switch it's self can give trouble, 1970s Ladas had the same ignition switch used on many Fiat models and I have experienced them fail on new cars whilst still in the showroom.
On inspection I found the load going through the switch in the start position caused heat to melt the plastic cam reducing the force closing the contacts as well as causing burning of the actual contacts.
Obviously if your model has the traditional pull lever to operate the starter then the load is reduced at the switch, but if a solenoid is used it may be an idea to fit a relay to take the strain off the switch.

 

[Fiat1212]

Thanks everyone for your help.
My volt meter shows a drop to 1.8 volts when I connect it the pos post on my coil. It shows 12 volts before I connect it. So something in the circuit is pulling it down. It does not drop only when the starter is engaged. The problem is not in my coil. I get the same drop with 3 different coils - 2 of those being new coils.
The wiring diagram shows the blue lead splits in to 2 leads after it crosses the fuse, in the main fuse junction. 1 of those goes straight to the coil and the other goes to the main instrument cluster, then goes to the ignition switch. I eyeballed my leads and found some mouse chew on one 5 inch section so I cut it out and grafted in a new wire with no improvement at the coil.
I noticed there is a separate fuse (can type) (not part of the fuse cluster next to the gas tank) that preceeds the lead going into the main instrument cluster. I don't see this fuse shown on the standard wiring diagram for the F model but both of my Fiat F's have these. So I'll replace it and hope this solves the problem.
If this doesn't solve the problem, I'll take out the ignition switch and check it for shorts.
BTW my ignition switch on one of my F's is on the dash and the other is on my column? Was the ignition switch moved to the column on later production F's or is this a custom change made by the former owner?
I attached a pic of my big can fuse on my unrestred F model. Do all 500's have these?

 

[bugsymike]

I noticed there is a separate fuse (can type) (not part of the fuse cluster next to the gas tank) that preceeds the lead going into the main instrument cluster. I don't see this fuse shown on the standard wiring diagram for the F model but both of my Fiat F's have these. So I'll replace it and hope this solves the problem.
If this doesn't solve the problem, I'll take out the ignition switch and check it for shorts.
BTW my ignition switch on one of my F's is on the dash and the other is on my column? Was the ignition switch moved to the column on later production F's or is this a custom change made by the former owner?
I attached a pic of my big can fuse on my unrestred F model. Do all 500's have these?

If you are talking about the aluminum can I think you will find it is the indicator flasher unit, it may have something like 2 x 21 as in watts written on it, assuming pre hazard light switch, in which case it may say 4 x 21 watt.
Turn indicators on and you may feel it ticking by touching it.
Can you tell by the design of the ignition switch on dashboard if it is "factory" or not? I suppose if factory it may have been at the time some were going to steering locks so switch best by steering column in some Countries and some older ones had not.

 

[fiat500]

Thanks everyone for your help.
My volt meter shows a drop to 1.8 volts when I connect it the pos post on my coil. It shows 12 volts before I connect it. So something in the circuit is pulling it down. It does not drop only when the starter is engaged. The problem is not in my coil. I get the same drop with 3 different coils - 2 of those being new coils.
The wiring diagram shows the blue lead splits in to 2 leads after it crosses the fuse, in the main fuse junction. 1 of those goes straight to the coil and the other goes to the main instrument cluster, then goes to the ignition switch. I eyeballed my leads and found some mouse chew on one 5 inch section so I cut it out and grafted in a new wire with no improvement at the coil.
I noticed there is a separate fuse (can type) (not part of the fuse cluster next to the gas tank) that preceeds the lead going into the main instrument cluster. I don't see this fuse shown on the standard wiring diagram for the F model but both of my Fiat F's have these. So I'll replace it and hope this solves the problem.
If this doesn't solve the problem, I'll take out the ignition switch and check it for shorts.
BTW my ignition switch on one of my F's is on the dash and the other is on my column? Was the ignition switch moved to the column on later production F's or is this a custom change made by the former owner?
I attached a pic of my big can fuse on my unrestred F model. Do all 500's have these?

I think you're on the right track to consider the ignition-switch as the source of the problem, especially the dashboard version, which was standard on earlier cars I guess until the very late '60s in the UK and from images I have seen, maybe longer on Italian-marketed cars.
The internal design of the switch is very basic and there is a relatively light amount of spring-force applied to the contacts. I had a problem with charging that was traced back to the switch being in need of a good clean. Happily, it is fairly straightforward to take apart and clean. After everything had been shined up and decontaminated, I put a small amount of electrical grease on all the contacts. It might help in verifying this if you were to put some gently sideways or upwards force on the key as you try to start the car normally.

@bugsymike is obviously right about the flasher can and the 500 never had hazard lights.

 

[Fiat1212]

My Fiat with the starting problems has this ignition set up. Is this a typical later production F model ignition switch?
The dash style ignition switch is easy to remove. But I can't figure out how to remove this column mounted switch.
There are no detents for screws and the polished metal cover doesn't unscrew.
Should I try and slide the rubber boot down on the bottom end, then pull the wire connectors apart?
I would like to avoid pulling the steering wheel and sliding the whole arm up off the column.

Notice my old style dash mounted key position hole is still there and covered by an aluminum cover which has me wondering if the former owner changed the ignition position.

 

[bugsymike]

My Fiat with the starting problems has this ignition set up. Is this a typical later production F model ignition switch?
The dash style ignition switch is easy to remove. But I can't figure out how to remove this column mounted switch.
There are no detents for screws and the polished metal cover doesn't unscrew.
Should I try and slide the rubber boot down on the bottom end, then pull the wire connectors apart?
I would like to avoid pulling the steering wheel and sliding the whole arm up off the column.

Notice my old style dash mounted key position hole is still there and covered by an aluminum cover which has me wondering if the former owner changed the ignition position.

Re the ignition switch in photo I suspect once battery disconnected and the plastic cover removed the switch it's self is held in place like the old 1970s Ladas I used to work on with a large wire circlip that you flick out with a small flat screwdriver hence the need to disconnect the battery to prevent it all shorting electrically, you just need to get yourself upside to to get a good view of the back of the switch.
If it is that type they are available, although most seem to be the Lada Russian version rather than a better quality Fiat one, just take note and make sure the wires go back in original positions.
Depending on condition as @fiat500 mentions it may be possible to service it, though on the Ladas the high current going through the switch was melting the plastic cams that moved the contacts causing the burning at the contract points due to a less than positive connection.
The steering lock it's self is mounted differently to the Ladas, they were clamped to the steering column in roughly the same position using snap off head bolts and I have undone many of them on customers nearly new cars using nothing more than a screwdriver, a small centre punch and hammer, tapping the headless bolt around until loose enough, the odd tight one I would hacksaw a slot in to make it easier to remove.
Yours in the photo, however looks more of a challenge, I suspect after wire brushing off you may find some "blind pins" at the barrel end holding it on, possibly needing drilling out, then the key would have to be in a certain position to release the lock barrel, hopefully your lock works OK
We did generally find the steering lock problem was caused by customers having poor pattern spare keys cut and the rough edges not been cleaned up on the wire wheel, so sharp bits dropped into the lock barrel with the usual consequences.
To this day if I have a locksmith cut a key for me I insist they do the wire brushing bit, though many say it is not necessary until I suggest they pull the teeth across their hand a few times, it can be like a saw blade!
Yours having the steering lock may have been to comply with import and insurance regulations in certain areas.

 

[fiat500]

Re the ignition switch in photo I suspect once battery disconnected and the plastic cover removed the switch it's self is held in place like the old 1970s Ladas I used to work on with a large wire circlip that you flick out with a small flat screwdriver hence the need to disconnect the battery to prevent it all shorting electrically, you just need to get yourself upside to to get a good view of the back of the switch.
If it is that type they are available, although most seem to be the Lada Russian version rather than a better quality Fiat one, just take note and make sure the wires go back in original positions.
Depending on condition as @fiat500 mentions it may be possible to service it, though on the Ladas the high current going through the switch was melting the plastic cams that moved the contacts causing the burning at the contract points due to a less than positive connection.
The steering lock it's self is mounted differently to the Ladas, they were clamped to the steering column in roughly the same position using snap off head bolts and I have undone many of them on customers nearly new cars using nothing more than a screwdriver, a small centre punch and hammer, tapping the headless bolt around until loose enough, the odd tight one I would hacksaw a slot in to make it easier to remove.
Yours in the photo, however looks more of a challenge, I suspect after wire brushing off you may find some "blind pins" at the barrel end holding it on, possibly needing drilling out, then the key would have to be in a certain position to release the lock barrel, hopefully your lock works OK
We did generally find the steering lock problem was caused by customers having poor pattern spare keys cut and the rough edges not been cleaned up on the wire wheel, so sharp bits dropped into the lock barrel with the usual consequences.
To this day if I have a locksmith cut a key for me I insist they do the wire brushing bit, though many say it is not necessary until I suggest they pull the teeth across their hand a few times, it can be like a saw blade!
Yours having the steering lock may have been to comply with import and insurance regulations in certain areas.

The anti-theft screws that you describe do ring a bell. I have only vague recollections from over forty years ago of wrestling with one of those barrels, but I think there ended up being a fairly straightforward way of doing this as long as you have the key; but I can't be sure or explain how.....the circlip idea sounds likely.

The chromed, plastic disk in the dash on some "F" cars was factory-fitted presumably either to use up dashboard pressings or because the steering lock wasn't universally fitted. My memories of the "L" are hazy, but it looks like this also applies to them. I know one foolish person who welded up the hole thinking it was a leftover from a previous modification.

 

[bugsymike]

The anti-theft screws that you describe do ring a bell. I have only vague recollections from over forty years ago of wrestling with one of those barrels, but I think there ended up being a fairly straightforward way of doing this as long as you have the key; but I can't be sure or explain how.....the circlip idea sounds likely.

Re the key position on some locks there is a discreet hole at the back that if a pin is pushed in against spring pressure , with the key in correct position it releases the barrel, but I can't say for sure on this type.

 

[fiat500]

Re the key position on some locks there is a discreet hole at the back that if a pin is pushed in against spring pressure , with the key in correct position it releases the barrel, but I can't say for sure on this type.

I think that's the one.....my struggles were with one that we bought from the auctions for £50 that had no key.

 

[Fiat1212]

I took the plunge and tried to remove the thick form fitted rubber booty covering the wire connectors but it wouldn't budge so I cut it off and found that all of my leads looked clean and intact...which meant I was going to have to dig into the key switch itself

 

[Fiat1212]

After hemming and hawing for the next day and looked it over again from a different angle and found the black lead had slipped off the blade connector. I pushed it back on and ...if fired right up! Thank god, because I could see no way of removing the key assy without having to drill out a pin or something, which meant I would probably have to pull the entire column just to get at it. Thanks everyone for your input. Now I need to sort out my non-working horn. Unfortunately the former owner installed an aftermarket one that works on a single power lead and a ground instead if the factory 2 lead. I'll post more details in a new post.

 

[bugsymike]

After hemming and hawing for the next day and looked it over again from a different angle and found the black lead had slipped off the blade connector. I pushed it back on and ...if fired right up! Thank god, because I could see no way of removing the key assy without having to drill out a pin or something, which meant I would probably have to pull the entire column just to get at it. Thanks everyone for your input. Now I need to sort out my non-working horn. Unfortunately the former owner installed an aftermarket one that works on a single power lead and a ground instead if the factory 2 lead. I'll post more details in a new post.

This ignition switch appears to be a similar one to the Ladas I worked on though with less contacts. They are just held in with a wire spring clip which with battery disconnected, clip removed with a thin screwdriver they just pop out, so easy to inspect for damage as long as you locate the key slot in original position and ensure wire clip safely back in place so nothing shorts against terminals.