B2000 No Power

Hi, I recently bought an 87 B2000. It starts and idles fine but has no power, it will only rev to about 4500 rpm and will only go about 50 mph at full throttle. The only problem that I can find is that it doesn't seem like the second barrel of the carb is opening. It doesn't open at full throttle with the engine running or not. What is the correct way to test it? Does it have to be under load?

It's a vacuum operated secondary, so yes, it only opens under load.
If you snap the throttle, while idling in your driveway, you can see it begin to open, but that's about it.

Try replacing the fuel filter, and check the plugs and timing. These trucks are not powerful, but you should at least be able to go 70mph.

It also sounds like your catalytic convertor(s) may be getting plugged too.

Thank you very much for the responses. I checked fuel flow out of the pump and it seems fine. Timing and plugs seem ok too. I also ran it with the three exhaust pipes that go into the intake disconnected and it didn't make any difference. I did find a wire disconnected, its a yellow wire coming out of the coil. Anybody know where this is supposed to go and if it will cause problems? I still think the secondary isn't opening because the throttle plate on the first barrel is clean and shiny and the second one is dirty like it hasn't had gas on it in a while.

saw this thread and thought it was gonna be a "lets state the obvious" thread...lol.. sorry, no offense meant to anyone

I believe the yellow wire on the coil is the tachometer lead.
After seeing the pic of the throttle plate, I believe you're right about it not opening.
Let me dig for a bit... In the meantime, maybe someone else will chime in.

That was my first thought too but it has a factory tach and it works fine. Thank you again for all the help, I need to get it running properly to pass emissions then I'll get a weber

Is there any chance of passing emissions with a weber and the stock cat? I don't think they do a visual inspection so that's not an issue.

Yes.

First time for me after having Weber and Arizona emissions inspection, guy didn't like that he could see some vacuum outlets capped off, so I didn't pass. Those vacuum outlets were previously hidden under the stock air cleaner, but were now visible (like if one's truck did not have power brakes or cruise control). So I just added extra lengths of vacuum hose to go from one port to another.

Some states testing they don't even open the hood.