So, I bought a '78 Toyota pickup not long ago. Since I've had it, it's always bogged a bit when the gas pedal is pushed. I recently lost my license due to medical reasons, n just got it back today. The truck sat for about 3 weeks at my dad's house n was not started during that period. I went to fire it up this afternoon n it tried for a bit before it kicked on. I thought nothing of it, as it had been sitting for that long without getting started. I let it warm up for about 20 minutes without any problems. The idle was spot on, as per usual. Once I got in the vehicle and took it for a little Drive it seemed like it was running fine but when I came to the first stop light is when I ran into my problems. At the stoplight it idled just fine, but when I went to take off it bogged down on to the point it died. It fired right back up with no problem but this time I gave it extra gas and kind of feathered the gas pedal and just kind of felt it out and was able to successfully take off. It seemed like the problem got worse the more I drove it by the time I reach my destination about 45 minutes away it was extremely difficult to take off from first gear and upon shifting into 2nd gear it would also dog down quite a bit before it regained its life. it doesn't have a problem with accelerating. I'm not sure what could cause this I'm just starting to get to the point in my life where I'm learning about mechanics if anybody can help me that would be quite amazing thank you very much!!!

 

Vaccumm leak?

 

How does one check/test for a vacuum leak??

 

Vacuum leak would surprise me as it is idling fine. My guess would be to check the accelerator pump on the carb, and to make sure that your choke is functioning properly. My truck does this when it is cold because I currently don't have a choke set up. If your choke is not properly turning off it could be causing this issue when warmed up and "get worse as you drive it" as you described. The other thing to check is the accelerator pump. That's a small plunger that spurts extra fuel into the venturi when you hit the gas pedal which keeps the engine fueled while vacuum builds and starts pushing fuel from your main/secondary jets instead of just your idle jet. Check to make sure it is actually working, as if it isn't it will cause the engine to bog when you hit the gas pedal. An easy way to check is to take off your air cleaner, make sure you have plenty of fuel in your carb float bowl, and just actuate the throttle with the truck off, looking to see if there is a stream of fuel that goes into the carb.

 

I would push more for the Fuel side of the issue, being something with the carb is out of wack.