What could possibly be wrong? I have a 73 f-250 WITH A 390 STANDARD IGNITION SYSTEM.Problem is when it gets run a bit the engine starts to cut out and I loose tach signal intermittently when it is missing and cutting out. I changed the Spark plugs the wires New distributor points condenser coil And no matter what I do It does not change anything. Could it be possibly the resister wire Failing? Or a Faulty wire or connection? How would I test to see if its the ignition wire?
Can I just temporarily bypass the Resistor To see if it still runs bad? Truck always starts good but always has a flutter or stumble as it gets warmer. Engine was overhauled 2500 miles ago so engine condition is not the issue. HELP! What is the Problem?

 

With the key in the run position, you should get 5-6 volts out of the resistor wire. Rudimentary, but it's a start...

 

Could also be your ignition box which typically rears its ugly head when warmed up

 

It is Standard Ignition NON electronic Points and condenser would not have an Ignition box. It does have voltage enough to light a 12 volt bulb dimly. Question tho, could a bad Ignition switch cause the Loosing voltage problem?
Everything else in the truck works fine just the engine bucks and jerks when it gets warmed up. Cuts out when you get on it real hard then gets to the point where you cannot keep it running very well

 

You could bypass the resistor, though not for very long. It's there for a reason. The points will burn up without it.

Where are you sourcing points and condenser?

The modern replacement parts sold at the auto parts shops are JUNK, even remanufactured distributors sport these POS. Try a good old school Motorcraft or Echlin condenser from "back in the day". I have 60 year old condensers that test fine at 600 volts DC. The new ones can't hang. In fact, replace the condenser even if it hasn't failed yet, because it will.

Could be a defective ignition coil as well. The key here is the issue arises when it warms up. Heat.

Coil or condenser is the likely culprit. The tach drops out, when the secondary high tension (spark) drops out.

 

You could bypass the resistor, but definitely only temporarily. Ideally, you could go to Radio Shack or where ever, and get a similar resistor, and wire it inline with the straight wire.
Coil should only see 12V during cranking, normally.

 

OP has a 1973 F250: DuraSpark electronic ignition introduced in 1974, but not all vehicles have it until 1976.

 

Yeah didnt notice that, when the comment was made I looked back at the OP and saw the date... Duh!

 

It sounds like a sad connection somewhere in the primary side of the ignition circuit. You may have to trace out the circuit with a voltmeter while the problem is occurring. It could be the resistor wire, but more likely a sad connection somewhere or in the switch.

Also as mentioned, don't "***-u-me" that "new" means "good". Try to verify each component's performance independently.

 

well Guys, I think I found my problem! Went and replaced the Points and condenser with New Quality ones from Napa Echilin brand and it seems like problem solved. Drove it all over this afternoon both slow and Fast and it never sputtered or quit. I bench tested the old condenser and it would definitely cause a miss sometimes. Just hooked it up to a battery coil set up and simulated the spark and it sparks sometimes and sometimes not. So I Assume problem solved !

 

I also found on some of the other condensers I have tried had abrasions in the condenser wire could cause a short within the distributor

 

Yes'er, I went cheap with my ignition parts recently on my rebuild and had nothing but problems.... Spent a few more bucks on quality parts and it runs like a champ.........One of those lessons we have to keep learning ..