Odd problem...Engine dies at idle

[WPS 73 Bronco]

So my 73 Bronco with a crate 302 with Edlebrock intake and 1409 carb has an issue that's confused me. About a month ago I was out driving, pulled up to a stop light. after 15 seconds or so, engine dies. I put it in gear and it cranked right up.

Since then, I've noticed this happening a bit more frequently. On Sunday it did it once, and then at the next stop light I thought it was about to do it again. I gave it a bit of pedal and it didn't die. When I got home, I put it in park and let it idle for 10 minutes. All was perfect. I'd guess the idle is running about 700 rpm.

Any thoughts as to why this would happen only when in gear? It's as if it runs out of gas in the carb. I don't think it's a vapor lock issue, but....???? Engine temp is around 180 on my guage, like always.

 

[NJBronk]

Any thoughts as to why this would happen only when in gear?

I have a manual trans, but when I was reading about setting my idle mixture after recently rebuilding my carb I noticed a different procedure for automatics, where idle is higher out of gear because of the load put on the engine in gear. Seems yours may have become more sensitive to this, which perhaps implies something changed slightly in your idle conditions. Maybe a small vacuum leak? I would start there (check hoses/vacuum plugs, spray carb cleaner around the carb/intake and see if idle RPM's increase, etc.)

 

[Broncobowsher]

Generally if the engine fades away into dying, struggles and stumbles a couple times before it dies it is a fuel issue. If it just flat out dies, running perfect, falls dead, that is ignition.

Under load ignition failure tends to be a hard step in power change. Where fuel tends to roll into a power change.

Not 100%, but where I start looking. When struggling to find a fuel issue, it is usually an ignition issue that is overlooked. When struggling with an ignition issue, it is probably a fuel issue.

 

[Brush Hog]

If it’s an electric choke make sure that is working and adjusted properly. I have an Avs2 carb and choke wasn’t opening. Presented the same as you describe. Adjust choke and opened air/fuel screws to 2 1/2 turns and runs great. I do have to adjust the choke every few months

 

[WPS 73 Bronco]

I already plan to replace my ignition tumbler as it's been sticking lately. I did pull it out and clean it and now it's much better. I should probably just replace the entire unit to play it safe. That will be my first action, then go from there.

 

[WPS 73 Bronco]

Update: I found that the hose connection on the in-line fuel filter, right before the carb, had a small leak that was getting bigger. That's why over time the problem was getting worse. I fixed the leak, and all was good for a few weeks and then it came back...the same leak. After working on it, fixing it again, and then it came back again! I decided that the real problem was the fuel line hose was too old and it was the real problem. Replaced the line from the fuel pump and now all is good.