I have a frustrating problem. It will not start when the engine is warmed up. I drive it for a few miles and let it sit. When I try to start it back up there is no spark. There is fuel going in to the carb. I changed out the coil, pickup coil, ignition module (on fender) and the ignition switch. I pulled the distributor and cleaned it up for ground reasons. It starts strong when it is cold or has been sitting for a couple hours. It sound to me like something is getting hot or bad ground when hot. Does anyone have any suggestions or answers?? Thanks.

 

I'd check the new ignition module, and have it tested. New doesn't mean good. then go from there.

Check the wires going from the module to the coil, and to the distributor. Might have a heat related problem in the wires. all connectors, wires and plugs tight?

 

Try removing the Radio Noise Capacitor from the ignition coil "Batt" terminal.

 

I replaced the module the 1st time this past fall with the cheapest one(looked cheap too), made in china. I replaced it again two weekends ago with a more expensive one and it looks like it is quality made. I checked all the pigtails, took them apart, cleaned and re-greased. Checked them on the ohm meter. All that checked out ok. Why remove the radio noise capacitor from the coil terminal? Thanks for the reply.

 

Can you buy new ignition wiring harness's for 1983 f250 w/460 electronic ignition?

 

A shorted capacitor can kill the spark and at times they short after getting warm.

 

I will try taking the wire for the radio capacitor off.
Thanks for the reply!

 

The next time it does it, try rapidly grounding and ungrounding the coil "tach" terminal with a jumper wire (disconnect wire to "Tach" terminal first) and check for spark. If you get spark, then the problem is in the distributor or module (or associated wiring); no spark, then coil or power wiring.

 

No hot start is a classic "bad box" problem. Since way back in the 70's (older Dodge boxes also did the exact same thing). There's no practical way for us to test the stupid boxes so we just have to keep swapping them out. I once got three new "bad" boxes in a row before getting a good one. Really ticked me off. Since then I've kept an eye out for used genuine Ford boxes in the junkyards and have stocked up on a couple. I've had better luck with them than the new replacements like "GP" brand.
It could possibly be the pickup in the distributor. I've only had one personal failure there, but it was complete, not cold OK and hot not OK. In contrast I bet I've had to throw away about 8 boxes over the years.

 

One way to find out is use some of this:
Part# : 21-403
SUPER COLD FREEZE SPRAY 10 OZ.
Price ~ $7.99
Component cooler chills to -60 F. 10 oz. spray can w/ variable flow. Non flammable formula. For detecting thermally intermittent components. By MG Chemicals.

Check with Radio Shack or your local electronics supply store (many different brands available), it's what the electronics techs use to find temperature sensitive components such as transistors, capacitors, IC's, etc.

 

GypsyR,
I am not sure what you are refering to re: the "Box" ? is it the ignition module?

 

My truck does the same thing. Starts right up when cold. After I drive for more than 5 minutes or so, it just sounds like the the starter is moving in slow motion like the battery is loosing power. Let me know if you have any luck. I think the part they are talking about is on the left side, top of the wheel well in under the hood. I thibnk it has 2 connectors.

Coneynew

 

Do not shotgun test ignition parts they are too expensive. Any decent parts store has an ignition module tester. They work VERY well and can even detect heat related problems on a cold module. If in doubt take a hair dryer or heat gun. In my experience they have been 100% accurate in diagnosing that problem even with cold modules.

Always use MOTORCRAFT ignition modules. The other aftermarket modules fail quickly, often within 6 months. It is obvious that the Ford OEM designers know something the reverse engineered Chinese knock-off makers don't know. When mounting a DS-II module always use 1/4" spacers between the box and the fender to allow cooling air under the box.

Remember older vehicles with worn out engines or engines in need of a tune generate much more under hood heat than a good engine which can contribute to failures of vehicle components, -especially electrical or electronic devices under the hood.

BTW- The ignition module on the fender is a DuraSpark II (DS-II) unit. The ignition module mounted on the distributor is a Thick Film Ignition (TFI) module. In my opinion mounting an electronic ignition module on a part bolted to a hot engine was a huge design error and AFAIK there was a recall and some sort of class action re the module. GM was successful with their HEI ignition module mounted in the distributor cap tho.

 

I eliminated the radio capacitor. I will try grounding/ungrounding the coil tach terminal this week.
Any other possible tests? Could it be a broken wire somewhere in the ignition harness?

 

This sounds probably too simple but I have run into this problem several times on Ford trucks,
Loose or corroded coil wiring terminals.
Steve G.