Trouble shooting help - '46 Deluxe

[FortyNiner]

Here's the basics:
'46 Deluxe - bone stock 6V 239 V8 (completely rebuilt 6500 miles / 8 years ago)
2 year old battery with clean connections
Grounds to frame and block with 00 cable
Distributor rebuilt by Third Gen 2 years ago - plug and coil wires replaced
Wiring replaced during restoration to OE spec
New fuel tank and lines during full resto in 2017/18
New radiator / water pumps in 2017 - no issues with heat or overheating

Background
Typically a ready starter after a few seconds of cranking - hot or cold

The Issue
Recently - like just this week - warm restarts are suddenly a problem.
Cranks as it should but doesn't fire. Fuel flow is good.

On the first instance, I used a jump box (after a few minutes of cranking w/o fire) and it started immediately. It has also started instantly if roll starting by popping the clutch in gear.

Today, I found that it will also start immediately if the ignition switch is moved to 'ON' while the starter is engaged.

What have I done?
Checked coil wires and swapped out the coil for a NOS version on hand (no change).
Coil does NOT get warm to the touch when in 'no start' mode
The coil I removed has been sent off to Skip for a rebuild.

Looking for wisdom from those who have been here before. What should I check?

I appreciate any inputs.

[Bruce_MO]

Maybe it’s flooded? Have a ‘53 that has always been a bear at hot restarts. If I shut it off (when hot) and immediately hit the starter, it starts in half a revolution. If I let it sit for a couple minutes, it’s very hard to start. I have to push the gas pedal down almost all the way and crank it for 8-10 seconds, and then it’ll catch and start. I think I have gas percolating in the bowls (two 94’s), and that’s flooding it and it seems I have to clear that out to get it to start. I’ve blanked off the power valves, have insulators under the carbs, and no improvement. A couple of your scenarios sound to me like you clear out the flooded condition and then it’ll start. Good luck; hot restart problems are definitely a pain. I think with some flatheads, you just have to find a combination of steps that work, and then repeat. I just finished a ‘46 Merc and it starts beautifully under all conditions. Wish I knew what I did right!

[FortyNiner]

Thanks for the comments.

This flathead does have a certain procedure, as most do. Doesn't seem to be a flooding issue as it has started immediately without the typical over fueled behavior (smoke and engine sputtering until clear). In addition, this engine doesn't need any choke - ever.

[JayChicago]

Like the coil, sometimes the condenser will work fine when cool and then fail when warm, giving weak spark. Condenser is cheap and easy to swap out, worth a try. When buying a condenser, might want to buy two; they are known to be bad out-of-the-box sometimes. And don't buy a NOS condenser; they will go bad just sitting on a shelf.

[glennpm]

Originally Posted by FortyNiner

On the first instance, I used a jump box (after a few minutes of cranking w/o fire) and it started immediately. It has also started instantly if roll starting by popping the clutch in gear.

Today, I found that it will also start immediately if the ignition switch is moved to 'ON' while the starter is engaged.

This caught my attention. Try running a wire that goes from the battery to the distributor side of the coil, bypassing the resistor. If that works, wire up a momentary switch that you can toggle while cranking. For normal running the resistor is in play.

Ignition Switch to Coil Resistor; Black with Red 16
(also found as Red with Blue)
Coil Resistor to Ignition Coil; Red and yellow 16
Ignition Coil to Distributor Points. Black 16

Links for your wiring diagram, https://www.fordbarn.com/forum/showp...44&postcount=5

[petehoovie]

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Originally Posted by glennpm

This caught my attention. Try running a wire that goes from the battery to the distributor side of the coil, bypassing the resistor. If that works, wire up a momentary switch that you can toggle while cranking. For normal running the resistor is in play.

Ignition Switch to Coil Resistor; Black with Red 16
(also found as Red with Blue)
Coil Resistor to Ignition Coil; Red and yellow 16
Ignition Coil to Distributor Points. Black 16

Links for your wiring diagram, https://www.fordbarn.com/forum/showp...44&postcount=5

[FortyNiner]

Originally Posted by JayChicago

Like the coil, sometimes the condenser will work fine when cool and then fail when warm, giving weak spark. Condenser is cheap and easy to swap out, worth a try. When buying a condenser, might want to buy two; they are known to be bad out-of-the-box sometimes. And don't buy a NOS condenser; they will go bad just sitting on a shelf.

Thanks for the input.

I failed to mention that this is a 59AB with the rabbit ear distributor - access is not easy, unfortunately. My plan will be to work the resistor angle first, swap out a fresh Skip rebuilt coil next, and go the condenser route if still battling the problem.

Originally Posted by glennpm

This caught my attention. Try running a wire that goes from the battery to the distributor side of the coil, bypassing the resistor. If that works, wire up a momentary switch that you can toggle while cranking. For normal running the resistor is in play.

Ignition Switch to Coil Resistor; Black with Red 16
(also found as Red with Blue)
Coil Resistor to Ignition Coil; Red and yellow 16
Ignition Coil to Distributor Points. Black 16

Links for your wiring diagram, https://www.fordbarn.com/forum/showp...44&postcount=5

Thanks for the input. I'll give this a try and report back

[69a]

[QUOTE=glennpm;2389411]
Try running a wire that goes from the battery to the DISTRIBUTOR side of the coil, bypassing the resistor.


Is this correct? I would have thought you would run the wire from the battery (non-grounded side) to the ignition switch side of the coil.

[glennpm]

[QUOTE=69a;2389450]

Originally Posted by glennpm

Try running a wire that goes from the battery to the DISTRIBUTOR side of the coil, bypassing the resistor.

Is this correct? I would have thought you would run the wire from the battery (non-grounded side) to the ignition switch side of the coil.

Running the test wire from the battery to the ignition side would be a way to see if the ignition switch is causing the problem. Running the test wire as I mentioned, would bypass the ignition switch and the resistor. To make a permanent change to bypass the resistor during starts, yes you would run a new wire from the ignition switch, to the distributor side of the resistor..



This change will give you battery voltage for starting and not a reduced voltage for protection of the points.

Glenn

[JayChicago]

"Today, I found that it will also start immediately if the ignition switch is moved to 'ON' while the starter is engaged."
This is a mystery to me. Any electrical gurus want to explain this? Starter is still cranking, still pulling down voltage available to the ignition circuit. Dirty ignition switch making better contact while transitioning from off to on?

[COE Dan]

Originally Posted by JayChicago

"Today, I found that it will also start immediately if the ignition switch is moved to 'ON' while the starter is engaged."
This is a mystery to me. Any electrical gurus want to explain this? Starter is still cranking, still pulling down voltage available to the ignition circuit. Dirty ignition switch making better contact while transitioning from off to on?

Hard to tell why this is true without more data, however it may have to do with the resistor. If the ignition is ON then a start is attempted, it’s possible the current flow heated up the resistor. Under heated conditions the resistor likely has more resistance than a cold resistor. If the engine is cranked and the ignition then flipped to ON, there may be less resistance in the resistor and starting is then more likely. This is a guess but it would make me want to check that resistor. Some of the newer repro resistors aren’t very good. I had a new repro act funny, found a NOS replacement and solved that issue.

Besides checking the condenser (another typical problem), if your running ethanol gas you could be getting bubbles in the carb or the fuel bowl could be boiling under high heat. Had this happen on my ‘39. I put a carb spacer in which helped but switching to non-ethanol fuel solved that problem.

[FortyNiner]

Originally Posted by COE Dan

Hard to tell why this is true without more data, however it may have to do with the resistor. If the ignition is ON then a start is attempted, it’s possible the current flow heated up the resistor. Under heated conditions the resistor likely has more resistance than a cold resistor. If the engine is cranked and the ignition then flipped to ON, there may be less resistance in the resistor and starting is then more likely. This is a guess but it would make me want to check that resistor. Some of the newer repro resistors aren’t very good. I had a new repro act funny, found a NOS replacement and solved that issue.

Besides checking the condenser (another typical problem), if your running ethanol gas you could be getting bubbles in the carb or the fuel bowl could be boiling under high heat. Had this happen on my ‘39. I put a carb spacer in which helped but switching to non-ethanol fuel solved that problem.

Thanks for your comments.

Interesting. I'm running a NOS resistor but it still could be misbehaving.

I've watched the fuel bowl and haven't seen any bubbles or had any vapor lock issues. The weather hasn't been at all warm and the engine temps have been unremarkable.

[Flathead Fever]

You need a voltmeter to check this problem out. I would check for voltage at different locations in the ignition system starting at the distributor and working backwards.

[JayChicago]

69a is correct in post #11

As I understood it, this is a warm restart problem. I don't think this is a voltage problem or he would have trouble with cold starts too.

BTW: I have tested five ballast resistors and watched them drop voltage as they get hot. They do increase the voltage drop as they get hot, but by only an additional 0.2 -0.3 volt. Negligable.

[Ggmac]

Have you replaced or rebuilt your ignition switch? Does it feelloose when moving the lever ? It could be worn to the extent that when switched to the on position it doesn’t have the tension to give good contact , but when switching to the on position you’re actually putting a little pressure on the contacts , thereby giving it just enough contact for good continuity? Just a wild guess without my coffee…..
Good luck , Gary

[FortyNiner]

Originally Posted by Ggmac

Have you replaced or rebuilt your ignition switch? Does it feelloose when moving the lever ? It could be worn to the extent that when switched to the on position it doesn’t have the tension to give good contact , but when switching to the on position you’re actually putting a little pressure on the contacts , thereby giving it just enough contact for good continuity? Just a wild guess without my coffee…..
Good luck , Gary

Thanks for the reply.

The ignition switch does not have any play and the connection block behind it was replaced with a NOS piece. I will inspect and check all of the contact points based on your comments.

[Terry,OH]

Suggest you place a voltmeter on the wire from the ignition switch to the resistor, see if the voltage dips badly. when the start fails and try it again when the start works well. The starter pulls max amps when it first starts once running the amps are much lower. Your battery should be checked for CCA.

[FortyNiner]

Originally Posted by Terry,OH

Suggest you place a voltmeter on the wire from the ignition switch to the resistor, see if the voltage dips badly. when the start fails and try it again when the start works well. The starter pulls max amps when it first starts once running the amps are much lower. Your battery should be checked for CCA.

What range of voltage should I expect when starting?

[Ken/Alabama]

Could be a dirty ignition switch. The contacts inside those switches get dirty and burned over time causing a high resistance to the ignition. Try placing a jumper wire from the Batt terminal to the Coil terminal on the back of the switch. I’ve had to remove and clean the switch in my 40 a couple times for these very symptoms.

[FortyNiner]

Originally Posted by Ken/Alabama

Could be a dirty ignition switch. The contacts inside those switches get dirty and burned over time causing a high resistance to the ignition. Try placing a jumper wire from the Batt terminal to the Coil terminal on the back of the switch. I’ve had to remove and clean the switch in my 40 a couple times for these very symptoms.

Good to know. Thanks!