wont start when warmed up

[davefrancisco]

Hello all,

My 77 spider won't start after it warms up. I can solve the issue by bypassing the coil resistor, so I swapped it out and same results. Also replaced Cap, Rotor, condensers and coil. Standard ignition duel points.

Any ideas/help appreciated.

Thanks

Dave

[SteinOnkel]

Is it not making a spark when it's hot?

Could be vapor lock in the carb. Modern fuel is pretty susceptible to it so we always run phenolic spacers in the carburetor cars.

Alternatively I would recommend binning the dual points ignition for the 1979 version. Search my post history, I've talked about it many times.

[davefrancisco]

Thanks for the response.

When the car is hot, it starts right up when I bypass the resistor, so not a fuel issue. I have an electronic ignition system on order. It's an upgrade kit that seems to have decent reviews. I'll be able to remove the resistor with the new ignition system, so hopefully this goes away.

Thanks

[18Fiatsandcounting]

Let us know how it works out. I have heard of some issues with the tachometer and electronic ignitions, in terms of the tach being somewhat erratic at times. The original Veglia electronic tach "counted" the pulses from the ignition points, and translated that into a current that moved the tach needle.

Problem is, the original tach needs a square wave signal in order to work properly, and some electronic ignitions generate more of a spike waveform than a square wave. The result is a tach that jumps around or is inaccurate.

But, give it a try, and you might be just fine. There are workarounds if you do experience an erratic tach.

-Bryan

[davefrancisco]

Thanks for the heads up on the tach. I'll update here on any conclusions I reach

Dave

[spider2081]

When the car is hot, it starts right up when I bypass the resistor, so not a fuel issue.

Many cars bypass the ballast resistor when the starter solenoid is engaged. You could accomplish this be adding a relay circuit to your car. However I wonder if there is a voltage loss to the coil when the starter is cranking. Have you measured the voltage on the B+ ( ignition switch) terminal of the coil? If it is less that 10 VDC then there could be a poor connection somwhere in the circuit or your battery may not be getting fully charged.

[davefrancisco]

@spider2081 and all. I do recall noticing a voltage change to the coil when it would not start. This was my reason for bypassing the resistor. From there everything was fine. Since I have purchased a new flamethrower coil that has an internal resistor and I need to see if I can recreate the issue.

I also found the wiring diagram for the 77 spider and it does not show a coil resistor. That doesn't mean there should not be one, but more investigations needed.

This weekend the new electronic ignition will go in. Seems simple enough, hoping no tach issues.

Dave

[SteinOnkel]

@spider2081 and all. I do recall noticing a voltage change to the coil when it would not start. This was my reason for bypassing the resistor. From there everything was fine. Since I have purchased a new flamethrower coil that has an internal resistor and I need to see if I can recreate the issue.

I also found the wiring diagram for the 77 spider and it does not show a coil resistor. That doesn't mean there should not be one, but more investigations needed.

This weekend the new electronic ignition will go in. Seems simple enough, hoping no tach issues.

Dave

On a lot of cars the coil wire itself is the resistor. Not sure how it was on the Fiat when I revamped the ignition system.

Flamethrower is expensive marketing and nothing special.

[spider2081]

@spider2081 and all. I do recall noticing a voltage change to the coil when it would not start.

If this voltage loss is not addressed there is no reason to believe it will improve. The Pertronix igniter requires more than 10 volts to provide a dependable spark. So if there is a excessive voltage loss when the engine is cranking a Pertronix system my not work. This is why the Pertronix install instructions state removing the ballast resistor.

[davefrancisco]

Here is the final outcome of this issue. I Set the timing properly, Installed electronic ignition and rechecked timing. The car is running well. And most importantly the car starts after it warms up, even with a coil that has a resistor.

Tach behaves fine, the needle is not jumping around.

What I discovered however was only the primary points were in use. The temp switch responsible for triggering the ignition relay was not connected.

Appreciate all of the help and guidance.

Next up is Carb swap.

Dave