i've got a 75 390 that runs perfectly fine and then out of nowhere dies. instantly. previous owner put in a new distributor so it doesn't have points. Has an Accell coil. I'm thinking it is something electrical but other than that I am totally at a loss. Any help would be appreciated, this is my daily driver that i have to get running very shortly so i can haul water for my house

 

You just have to run it down. When it cuts out, is there fuel in the carb? Is there spark?

How long after it dies, how long until you can start it again?

Air, fuel, spark. You got those, and it won't run, look for poor connections upstream of the spark. Good? Look for problems with the fuel system such as clogged lines, damaged pickup, dying fuel pump.

Good luck with it.

 

Does it seem random, shut off at any time, or maybe only after it's been running for a while i.e. do you think it may be heat related somehow.

 

it appears to be completely random. from just after it starts to running for 30 minutes. sometimes i can start it right back up immediately sometimes it takes multiple times before it will start. from zero times in a 20 mile drive to 10 plus times. could a failing coil be the culprit? i've got gas, pulled the line after filter and gas came out from carb side. under pressure. cranked it while it wasn't starting and fuel pump was pumping plenty of fuel. haven't been able to check spark as its just me working on it

 

Given those symptoms, sounds like some kind of intermittent connection or switch. Try wiggling some wires at idle and reproduce the fault?

 

If you have a spare coil, try that.

 

Check the wires to the coil for cracks , the power can ground out through the cracks .
Also if coil is mounted on the engine , it could be failing as it gets hot (i had this problem was a real bitch to pin point )

 

replaced the coil and coil to distributor wire yesterday morning. so far so good

 

started doing it again last night. looks like this weekend I will be tracing down wires

 

I wondered about that. Some of the modern coil brands seem to have problems in recent years, but doesn't seem like that's the problem here. Something sticks in my failing memory banks about the ignition switch itself.

Not really suggesting shotgunning parts so much as they aren't expensive and fall into the wear item category like plugs or wires - with "dimmer" and headlight switches for example. 40 (forty) years on anything electrical like breakers or switches is good service and needs preventive maintenance by now.

 

the ignition module was suggested to me today as a possible culprit. i think i have some on some other parts trucks so i am going to give that a try next. 40 years is a pretty good life for a part though, i will keep the actual switch in mind too. also, i've tried wiggling wires while at idle and after it quits and i can't get it to duplicate the problem

 

The ignition modules in the mid 70's were very finicky. I had a 76 Pinto and I kept a spare one in the vehicle. It would shut down and then 10 min. later start back up and run like there never was a problem. Pep Boys sold a ton of them.

 

apparently the jokes on me. distributor switched to electronic but i dont have a control module. atleast not one that isnt incorporated into the distributor. guess tomorrow i'll try swapping out the switch

 

What distributor is installed? Might seem like a step backwards though for troubleshooting, a known good set of points and condenser might be worth a try, was FORD still using points in 75?? Maybe not. A backwards compatible distributor though, is nice in case of trouble on the road with electronic unit.

 

the distributor is a Mallory unilite.