Help: 85 305 Suddenly Stalling in Gear

[Trucksareforwork]

Ok, here's the deal: 1985 C10 with a 305. No air pump or EFE, but all other vac lines are updated and intact. Truck has run like a champ for more than a year after a light restoration (thread elsewhere). I'm having trouble suddenly and wanted any quick ideas. The story:

The truck had to be parked outside for most of the winter after I lost access to some shop space. I drove it a few times, but not a lot. Maybe less than 100 miles.

Then, I suddenly started to get a stall situation while in gear and warmed up. Truck would warm up fine, then when I would get to a stop sign it would just...quit. I can't even describe it any differently. No sputter, no struggle, just...Off as if spark has just stopped.

I fiddled around and realized that my distributor hold down was a little loose, and so figured I had just slipped timing a little bit. Got out the timing light and re-set timing over the weekend. Ran good/great after that. I thought I had solved the problem.

Then today, I needed the long bed for a project, and figured what the heck, I'll take it out on the road. Got outside the driveway and... just stopped. Then couldn't get more than a sputter on re-start. Got pissed, left it there, came back in two hours and got it started (cold again) and pulled it back in the drive.

Any idea what could be causing such behavior? The Distributor seems plugged in well (my first thought was the pigtail getting intermittent), I THINK all the vac lines are intact...they were mostly replaced in 2022.

Is there something in the carb (quadrajet) that would cause this behavior after warming up? My other theory is perhaps a major vac leak related to one of the TVS's (since the issue shows up after warming up), but I don't hear anything. Anything else?

I'm just looking for ideas. Starts cold, then stall, then basically no start after the stall.

Thanks!

 

[viaminveniam1939]

I’m NOT at all qualified to answer this… could it be vapor lock?

 

[fast 99]

Shutting off first thing to check is spark. There are many issues that can cause it, but number 1 is module second would be a coil or pickup. If a moule is replaced use enclosed dielectric on base. Be sure and check for power supply at distributor first.

Without being there next would be a vacuum leak or bad idle circuit but the vehicle should at least re-start then die.

 

[Snoots]

If you have HEI, I would guess the pickup coil in the dizzy.

 

[Ricko1966]

1985 305 should be esc distributor the controller behind the glove box does funny stuff when they start to fail. I'll find the info on the bypass and post it in a few minutes short version I tell you how to make the bypass jumper,you keep it in the truck,next time it fails, put in the jumper.If the problem goes away we,'ll discuss ways to fix it,advantages and disadvantages.
Okay here's the info carry this pic on your phone and a piece of wire with each end stripped and roll of electrical tape in the glove box. In the pic this is the connector on the distributor side,unplug it from the harness coming out of the firewall and instead of cutting anything put your jumper wire into A and C ( black and green) tape it in place and see if that makes it run again.

 

[brooksman9]

Agree with Snoots. Had the same issue with a 79 Vette we had once. Pulled the distributor and replaced the ickup coil. Problem went away. Probably easier to just replace the damn distributor though unless there is something special about that one.

 

[Ricko1966]

Agree with Snoots. Had the same issue with a 79 Vette we had once. Pulled the distributor and replaced the ickup coil. Problem went away. Probably easier to just replace the damn distributor though unless there is something special about that one.

There is something special about that one. It should be esc. The 2 biggest failure points are the esc. controller and the module. In my expierience a problem that comes and goes with them it's the controller.