Michael - thanks so much for the quick and helpful reply. I've been immersing myself in this site (specifically the engine/carb info) over the past few days, and am very grateful for the volume of helpful info on here. Other than this site, there seems to be a dwindling amount of support/parts for these old IH trucks anymore.
This is my first carbureted vehicle, though I have had some mechanical experience with fuel-injected vehicles (built/swapped a motor on my Nissan). I'm pretty overwhelmed by all the tiny parts and adjustments on a carburetor, but it seems like there are enough how-to threads on here with detailed photos that I May be able to tackle it.
I also noticed the strange choke linkage you mentioned, as it didn't match up to any of the photos I'd seen of this carb. However, I'm a bit confused, as it has an under-dash mounted manual choke lever in the cab which appears to be stock. The linkage and cable don't really look stock though, so I'm wondering what happened.
Anyway, a brief background of my weeks-old history with the truck might help a bit, so here goes. It ran great when I got it...quick and steady throttle response, fired right up every time, never stalled. After a couple of days, it stalled randomly while driving and I had to pull over. It started up pretty quickly thereafter, but irked me nonetheless. This happened a few more times (seemingly at random...sometimes cold, sometimes completely warmed-up, but usually when I was going from no throttle to lightly pressing on it while coasting) over the next few days. Now, somewhere along the line, someone had installed an electric fuel pump with a manual switch on the dash, which I was told was only to prime the carb after it had been sitting for awhile, but was not to run in tandem with the mechanical pump. After it began stalling, it got me thinking this thing has had fuel-starvation issues in the past. When I inspected the mechanical pump and compared it to photos online of new pumps, it looked like it had been bent/crushed a bit, as the two columns leading to the fuel lines weren't completely vertical and there was a dented area in the main housing. I thought this might be hindering the diaphragm to operate correctly or make a proper seal, so I bought a new mech. Pump and installed it, thinking this would help the problem. The truck fired right up, even quicker than before, and ran strong for a few minutes. I backed it out of the driveway and put it into drive, and as I pressed the throttle lightly, it died again. It started a few times after but the same thing would happen. Now it won't start at all, and is flooding.
After searching around, it seemed like the symptoms I'm having could be traced to vacuum problems or to a choke pulloff or choke thermostat. But it also seems that I don't have those on my carburetor anymore...? I also wondered if the carburetor had been adjusted to operate at a certain (reduced) fuel pressure, and if it is now flooding because of a normally-operating mechanical pump.
I'm sure I've inherited yet another problem-child that was only fixed-up to run long enough to sell, but I'm here to learn how to get it running reliably and for a long time, because I love this old truck, despite its apparent intent to infuriate me. Luckily, I love to learn!
I'll be sure to get the door plate numbers and any under-hood numbers as soon as I get off work and can get to the truck.
