I have an 84 150 300 1bbl..Problem is its missing/stumbling real bad..will barely idle sounds like it has like a .600 lift cam in it..it will accelerate fine although you can still feel the stumble..I have replaced cap,rotor,plugs and wires and put a new fuel filter in it this morning also have ran carb cleaner through it no change..Unplugged O2 sensor made no difference and took egr off and cleaned it also choke seems to be working fine. Anyone have any suggestions what else I could check?

 

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try checking all ur vacume lines and make sure none of them are cloged or leaking

 

I would think the it is the carb after a tune-up and checking vacuum and intake leaks. The 1bbl carb is known for "going south" at the wrong time and without warning.

 

grad the carb and see if it wiggles side to side.
there are a couple screws on the bottom of the carb that like to loosen up and cause a big vacuum leak.

 

could be intake manifold too? Vacuum leak is an easy check. While the engine idles, take carb cleaner and spray around the outside of the carb and manifold - anywhere there may be a vacuum leak. Listen for a difference in engine RPMs.

 

I went thru every vaccuum hose and everything. No leak. Im almost convinced that the carb is causing the problem. Thank you for all of the input guys !


Doug

 

i had the same problem on my 84 300I6, just had to get the idle mixture screw and the timing set right, truck runs great now