Throttle position switch adjustment

[A guy named Rick]

I searched, can't find adjustment procedure for throttle position switch on a 720. Just want to make sure I have it adjusted right.

 

I had the truck running great, still can't drive it because smog and back registration fees. But, I messed with the timing and the throttle position switch, started it back up and revved it a bit, then coming back down in idle it started surging, like about to die out. Finally it died. Idk wtf is going on.

 

BTW, bottom radiator hose is always cold to the touch. Top one gets hot though. 

[A guy named Rick]

Just some info for those that haven't seen my other posts, I rebuilt the carburetor. It's off a 1984 720 pickup. They were running a mc solenoid from a 1.6L nissan sentra. Shouldn't be much of an issue. Finally got rid of air leak around the stud bolts, since I had no washer under the nuts and the studs were a little too short, so the misfiring went away with that. Was idling pretty nice and great throttle response, barely any stutter at all.

 

As soon as I messed with the switch, and set timing again, that's when he'll broke loose. Sputter when hitting the gas, revved it a little, then coming back down it started dipping low, then back up and down like maybe it was swinging rich and lean. Idk. Looked at carb window, fuel level was right and stayed that way while this happening. Mc solenoid works. Idle cut solenoid works. Throttle switch tests fine. Vac lines are fine.

 

Only thing I haven't done is change the oxygen sensor. Maybe my temp gauge is wacky and it overheated and I didn't know?? Plugs are new. Gapped correctly. I've gone through this truck with a fine tooth comb. 

[datzenmike]

The throttle valve switch...

 

 

You need to pull the plug apart on the back of the carburetor and make 3 short jumper wires to connect the WHITE to WHITE. BLACK to BLACK. YELLOW/BLACK mixture solenoid to it's mate on the harness side.

 

Check that the GREEN/WHITE wire (throttle valve switch) on the carburetor plug should NOT be at ground potential.

 

Start engine and rev to about 2K and verify that GREEN/WHITE wire IS grounded.

 

Decrease engine RPMs to 1,350 and GREEN/WHITE wire should open and no ground.

 

 

If not then hold at 1,350 RPM and adjust till the circuit opens.

[A guy named Rick]

Haven't had time to work on it until today. So here's what's going on...

 

The red and black wires to the anti diesel solenoid are exposing the wires in a small spot. It still tests 30 ohms and also clicks when testing it with gator test clips.  

 

When messing with the tps (before posting this asking for help), I touched the screwdriver to the wire accidentally and it sparked. It was after this, adjusting tps, and setting timing, that everything completely changed. Leading me today to test voltage to the wires on the vehicle side of the 6-wire plug and finding i have no voltage going to the anti diesel solenoid with ignition on.

 

What could I have shorted out? A fuse or something? 

[A guy named Rick]

Damn, nevermind. Get this: the 2 ground wires screwed under the carburetor,one is stripped and twisted with the positive wire. I undid them before testing, put them back how I found them and now I have voltage. Interesting. So that was a patch for a bad ground somewhere else.

 

Now I am stumped why I decided to not want to idle properly when I had it running beautifully.