Carb Choke Linkage

[m75]

One for Rickf....

I have been experiencing throttle problems recently. Truck runs great, then suddenly starts to sputter, die out and even after fluttering the throttle, will die. Starts right back up, runs a short time, then seems to starve itself out again.

When this happened the first time, I was having problems with the choke cable, which seemed to be really difficult to adjust. I removed the cable stay, pulled the cable out of the choke and made sure it was open, then started it again, Ran fine.

I replaced the cable, made adjustments at the throttle linkage, and ir ran fine again until today. Starved itself as reported above. I again removed the cable end of the choke cable and it ran OK afterwards.

The cable is routed per the TM, with a cable tie to keep it aligned and not kinked. When manually working the choke and its linkage, it seems to bind a little in the area between open/closed. Is this normal? I'm wondering if the linkage assembly has a tweak in it that I can't comprehend?

[Mark]

I'd look at the fuel filter, maybe the gas cap vent is closed

[rickf]

The choke cable should be smooth all the way through the travel. It may have gotten kinked at some time in its life. It usually set mine so that the choke is fully open just a hair before the knob hits the dash, this way I know that when I push it all the way in then the choke is all the way open. I have to agree with Mark that it sounds like a fuel issue, Is it consistent or random? When I say that does it do it at the same point in a ride every time or just whenever it feels like it? The gas cap issue that every points to is a rarity, It takes a long time to build enough vacuum in the tank to overcome the fuel pump, especially a healthy mechanical pump. A clogged filter is a good possibility. Another possibility is a hole or crack in the line between the pump and the tank pulling air.

[m3a1]

If you have one, check that often overlooked fuel pickup tube filter in the tank from time to time.

[m75]

I'll check later today. The tank was boiled out and repaired when I installed it, all lines are new (steel and rubber), just added new fuel pump and filter, Rick rebuilt the carb, new inlet filter, new choke cable..........

When the cable is disconnected, as it sits right now, the choke linkage feels as if it's binding when moving through the full range of motion. Is this supposed to happen, or should the choke movement (again, not counting the cable issue) be smooth across the board?

And, although the fuel cap has a new gasket, I'll check for the proper cap and setting if it is selectable.

[rickf]

Choke should not bind at all when disconnected but there will be some resistance if you have the throttle spring hooked up since the idle stop rides on the cam that is attached to the choke, as you put the choke in that cam raises the idle speed hence the feeling of resistance. If you take the throttle linkage off then there should not be anything at all. That is something I specifically check for since a lot of them come to me with bent linkages.

[m75]

Rick, you are sooooo correct.

I was trouble-shooting yesterday, and relaized just that, that the idle stop screw rode the choke linkage, resulting in the pressure on the linkage. When disconnected, it flowed with no resistance.

I pulled the screw-in fuel filter off and found some type of sediment in it, very fine particles. I blasted both sides with carb cleaner. Then I removed the carb, pulled the lower bowl and the diaphragm cover and blasted every nook and cranny, removing some sealant from the old carb mount gasket as well. put everything back together, then added a splice-in fuel filter before the carb-mounted filter, for extra insurance and visibility of the incoming fuel. Reset the choke cable, crossed my fingers and spun it for ten seconds without the ignition switch on. Then flipped the swith, cranked it and it came alive much faster than I expected it to, as the carb had been drained of fuel earlier.

Now, with the turn signals finally fixed and a replacement headlamp on the way, I might be able to say the mechanicals on this truck are done, and it's time to look at repairing the body issues (rocker panels, fender extensions, lower rear panel rust-through). But getting the mechanicals was always the priority.