Bronco stalling on highway and won’t restart.

[rbwamsley]

@DirtDonk here are some more (possibly better) pics.

 

[DirtDonk]

Thanks. Easier to see some things.
Can you get some pictures close-up like that of the wires leading into the distributor too?
I’m already questioning the wiring and since your symptoms seem to be electrically related, after seeing the distributor wires, I’m probably still going to recommend replacing at least the wires. And make another recommendation or two as
Better connections, fewer crimps, more “known“ commodities, and cleaning things up. I’ve never seen a relay like the one on your wheel well, but that doesn’t mean it’s not effective.
It looks very well weather sealed, but it also looks extremely old and already one of the wires on the left has split and is exposed to the air. Not the best location for the relay, and also not in the best condition.

And even though the starter is not causing you, any trouble, the starter relay/solenoid to starter cable looks rusty and has seen better days. In fact, your positive battery cable has seen better days as well.
Speaking of which, we can’t rule them out as part of the problem as well.
I still think it’s your distributor and/or distributor wiring. But at some point, the cables will need to be renewed.

 

[rbwamsley]

Long overdue update. Unfortunately I don’t have the time for the Bronco that I had in the past. Kids eat up the majority of my time.

I finally got around to installing a fuel pressure gauge and it helped diagnose the issue. The Bronco did its thing, stalled again and wouldn’t restart. I set up my phone to record the gauge as I tried starting it, and there was no pressure at all.

So what in the fuel system is the actually problem? Can mechanical fuel pumps have intermittent issues? Seems to me they would either work or not. If it isn’t the pump, what else could it possibly be?

 

[hsach]

There is a rubber diaphragm in the fuel pump, it gets eaten away over time. Now it can't keep up with the pressure needed for your carb, and it isn't a steady/consistent problem. It depends on driving conditions, heat, elevation, ect. Change it for a new one, it will be the easiest way to track down the issue. If there is no change, you have a new $35 pump and now know the problem lies elsewhere. The pickup filter in the tank could be blocked, or in the case of my '78 bronco, it could be missing and pieces of it could be blocking you fuel supply. Every fuel pump I have changed in the last few years had a weak or non-existent diaphragm compared to the new one I installed. And it has been a crap-shoot if the new one lasts. I switched to non-ethanol gas over a year ago, but that didn't stop the last fuel pump from dying. I had similar symptoms as you.

 

[MarsChariot]

From experience two things: Fuel filters and coil. Then all the reasons stated above.

 

[76BroncoPete]

Had a similar scenario awhile back. Original gas tank had a lot of rust and trash in it. Changed the tank has been fine since. Although it will probably leave me stranded again now that I made the claim that it’s fixed

 

[rbwamsley]

Had a similar scenario awhile back. Original gas tank had a lot of rust and trash in it. Changed the tank has been fine since. Although it will probably leave me stranded again now that I made the claim that it’s fixed

I think this is the path I’m leaning towards. Just replacing the whole fuel system. My sending unit works sometimes and I have no idea how old the tank is. It doesn’t seem to expensive to go with a stock replacement.

 

[76BroncoPete]

I think this is the path I’m leaning towards. Just replacing the whole fuel system. My sending unit works sometimes and I have no idea how old the tank is. It doesn’t seem to expensive to go with a stock replacement.

I was chasing vapor lock and all kinds of things. It was driving me crazy. Always seemed to happen at the worst possible time too. Hope it helps.