I've got limited internet so I apologise if there's a specific post regarding this, search isn't great with 1bar!

1985 Carbureted 460, 38k miles.
EGR/Air Injection removed and all associated vacuum lines.

Recent tune up including cap/rotor/plugs/plug wires/filters (air/fuel/oil).

We've done nearly 2000 miles since Friday with no major issues.

Yesterday we pulled into our campsite with no issue.
The next morning we had a power steering line blow and at the same time (not saying these are related) and (I also can't say this is related) and drove about 5 miles to fuel up.

After fueling up I began to notice idle issues (stalling at stops, low/rough idle).
Seems fine when you get going.
I can't say if it's fuel related because as I recall it started and was running fine that first 5 miles but, it also wasn't warmed up.

It sat for a few hours after that, and started and ran fine, until up to temp, when it started stalling at stops again.

Could this be ignition module failing? I have a spare, reading beforehand how these carb be an issue and many people seem to carry a spare.

We're also at pretty high altitude (5000') and the truck is from NC, but that hasn't seemed to be an issue from Denver, CO to Moab, UT

Thanks in advance for any ideas.

 

Two thoughts:

1) When the power steering line broke, did any fluid spray on the spark plug wires? Oil-soaked plug wires can cause rough running.

2) You first noticed the problem after filling up with gas. Perhaps you got some from a bad batch? Another factor is some of the special blends mandated for certain regions are rarely optimized for an old carbureted engine. Some more details here:

https://www.ford-trucks.com/forums/1...g-and-you.html

 

Good point.
Must of the spray was localized to the front of the engine but I cleaned everything off after the blowout and no difference.

I think it could certainly be at least partially fuel related.
I'm going to try and top off with different gas and see if there's any difference, and also take the doghouse off and double check all the vacuum lines.
I feel like there could be something that came off, as quickly as the difference came about.


I changed the ignition module and there was no difference.

 

Idle mixture screws may need to be turned in a little bit at that high altitude. That's one of the great things about electronic fuel injection, it adjusts itself continually.

 

Indeed on the EFI!

I I was under the impression that these Factory Holley carbs didn't have a idle adjustment per say, other than a lever screw?
I kind of feel like that would be treating a symptom at this point though, as we've been in some pretty high altitude for about a day and this is the first time it's acted like this, and it's done it ever since yesterday morning.
Now it pretty much does it right off the bat, doesn't wait to warm up or anyting.

I'm about to pull the dog House off while the wife and kids are out playing in the park, and hopefully I can get it sorted out before they're done.
The plan is to head towards lake Tahoe tonight, I think.

 

If that factory carb has been rebuilt, you should be able to get to the screws. If it's never been rebuilt, it's long overdue. Putting a rebuild kit in it will upgrade some of the rubber parts and they will hold up better to the ethanol in the fuel.

 

I think I'm just going to replace/upgrade the whole unit after this trip.

This had been disconnected the entire time, until now.
I can't say whether this or bad gas was the culprit but we've done about 700 miles since running vacuum to this Ave burning off the fuel and so far so good.
Good idle at stops, decent mileage and power.

Let's hope that's it for this trip.

 

to clarify, the one that my finger is touching was just laying there and the other one had the vacuum line burned off of it.
I took out the broken connection and ran a line to it from one of the blocked off, red vacuum lines.