Hi Everyone,
I am a novice with carbs. I have an 82 TA. lg4 and stock carb. Been sitting for a year. When I start it, it immediately acts like the throttle is all the way down. Just revs like crazy. I cleaned everything with carb cleaner, throttle linkage is not sticking, swapped out fuel filter, etc.

Why is this happening? is something internal sticking? how can I check all those solenoids (TPS, MC, etc.)? I really don't have alot of cash to buy a new carb and need to try to fix.

please help carb experts!

Thanks

 

Fast idle cam sticking or big vaccuum leak are most likely.

Fast idle is under choke housing on ps of carb. Move the linkage around and make sure you can get the throttle cam on ds side of carb to rest against the idle speed set screw. The spring should be pulling the lever towards the firewall pushing the other end of the lever (below the pivot point) into the set screw. Make sure the idle load compensator is not holding the throttle open while you're there. It's the solenoid front ds of carb.

Plug all the vaccum ports on the carb with caps to check for leaks. May have to put a cap on the hard line that comes out the back to the brake booster, too.

 

Thanks for your reply. I checked the cam screw and it all seems ok.

Let me be a bit more specific.....

When the car is cold, and I pump the pedal it starts but then dies. This happens over and over for about 4 or 5 times. Than I start the car, little push on the accelerator and it stays running but it is reving high. Then I let go of the pedal and it stays running. Then all of a sudden it goes full throttle and the engine is running like mad.

Again, no throttle cables are sticking and all connectors are tight.

Would you still think a massive vacuum leak with the above detail? How can I diagnose a large vacuum leak?

Thanks again for your reply..

 

If your choke wire is connected and choke blades are 90 degrees straight up..

I would think vaccuum leak. It's been sitting for a while and a hose somewhere may have deteriorated. Some of these lines are opened by thermal vaccuum switches (TVS). I like to get a set of vaccuum port caps and remove every vaccuum line from the carb and cap each port. If the carb runs fine with everything capped you can then reconnect each line one at a time until you find the one that is leaking, then trace the line. Sometimes with it running you can clamp on each vaccuum line with a set of pliers to check, but it's, not as definite, but may work in your case.

Don't forget to check the line from the rear of the manifold and the brake booster.

 

Thanks NAF for your continued help. I will take your advice and check all vacuum hoses, etc.

One other question. I see (2) adjustable screws. One on the driver side below the throttle and one on the passenger side under choke. How can I set these to the default settings or correct settings? I have no idea who has messed with these in the past. Is there a certain settings these should be set at?

Will update later regarding what I find with the vacuum hose check.

Thanks Again!

 

DS is idle speed set screw, PS is fast idle (choke) idle speed set screw. For adjustments you can refer to:

https://www.thirdgen.org/forums/carb...s-problem.html