1978 FJ40 Carburetor and Vacuum (1 Viewer)

[Rayberne]

May 1978 build date with California emissions starts and idles perfectly, but won't go faster than around 10 MPH. No stutter or backfire, more like starving for fuel.

Attached photos show what is under the air cleaner. Aftermarket carb without fuel return line. Vacuum from the carb hooked directly to original distributor, idle solenoid connected. Otherwise just lots of disconnected wires and vacuum lines. New-ish original style mechanical pump delivers plenty of fuel. It looks like a new fuel filter.

Given the current state, where do do you think I should look for whatever is limiting RPM?

A

 

[fjc-man]

Try manually operating the accelerator linkage from under the hood. Does it achieve opening the primary side throttle plate straight up vertical? Next have a helper push the gas pedal to the floor, do you get full throttle?

 

[cbmontgo]

Is your primary opening when you hit the accelerator? Not sure what that small shaft is coming out the bottom, but it looks disconnected.

The fuel delivery should transition from idle to power when the throttle is applied.

 

[Rayberne]

Fixed it! There was a problem with the choke/fast idle complex of linkages at the back of the carb. When operating the throttle linkage from under the I could reproduce the symptom - when the throttle opened past 1/3 way, the engine bogged same as when driving. A little more searching and fettling behind the carb revealed that the linkage was very loose and mal-adjusted. Tightening up and removing (most of) the slack fixed it.

Thanks for the tips! They pointed me away from all the loose wires and hoses and back into the carburetor itself. Thanks again.