I've got a 90 pu with the 22r. It's been stumbling occasionally when driving a consistent speed. So, I put some higher octane fuel in it to see what would happen. Well, it seems worse now. So, I popped off the air cleaner and, well, pardon my ignorance (I'm used to 4 bbl carbs), but this thing seems to have one jet and 2 intakes? Is that right? Anyways, the intake, without the jet in it, is mostly closed (butterfly valve) even when warmed up.

SO, all that to say: Is this a vacuum problem? Is this valve run by the EGR? I need ideas here... thanks in advance.

 

did you search ?

 

Search for what? "What's that carb part?"
I mean seriously.... Isn't my question(s) a little too nebulus for that?

 

Try Seafoam or other carb/injector cleaner?

Electric choke on these IIRC.

When mine started doing that, I just replaced it with a Weber 32/36 and never looked back.

 

So is that second butterfly valve supposed to be shut even after warming up?

 

No. Only closed on warmup

 

Um, by "on warmup", do you mean while warming up? Or after the truck is warmed up?

 

While warming up. On a cold engine after you turn on the key(not cranking yet),you should step on the throttle fully a couple times. That should close the choke fully, then start it up. the truck should run at high idle for maybe 2-5 minutes then kick down automactically, opening the choke butterfly.

Sounds like your choke isn't working correctly.

 

I didn't know they still used carbs on 90's???

 

2wds were available carbed until '90 or '91

on a lot of the carbs, the secondary choke flap stays shut until you mash the throttle. that's why putting on a weber 32/36 often increases performance, since the carb isn't operating at full potential.

if your engine is stumbling at constant speed i might check the EGR system to make sure it's functioning properly.

 

Where is the EGR on these things? A buddy of mine said to just disconnect the EGR and see how it runs after that...

 

EGR is the little gadget next to the intake manifold towards the back of the engine.