1/79 fj40 falls flat at initial acceleration (1 Viewer)

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Rather than chase my tail around. I am trying to find the source of my fj40 falling flat on its face for a moment on initial acceleration I have changed all vacuumed hoses and had my carburetor rebuilt by Marlin I am ruling those things out. It idles smoothly and runs fine otherwise. I am leaning towards the distributor duel advance.
 
Even with the carb rebuild make sure you’re getting a squirt of fuel at accelerator peddle depression.
 
I was thinking accelerator pump also, there are enough rigs running around with no vaccumn advance because the pod isn't working, I have a hard time thinking that is your issue
 
There isn't enough vacuum at initial take-off to make the vacuum advance kick in anyway. You'd see a non-op vacuum advance more as a flat spot when the revs get up a bit, usually when you're about ready to shift. My money is on a vacuum leak near the carb, or the accelerator pump. Hook up a vacuum gauge and see what your intake vacuum reading is.
 
Hook up a vacuum gauge to the one of the vac ports on the base of the carb and see reading at idle. Should be 18+inches of vacuum. Spray carb cleaner to the base of the carb at idle and see if any spot location hit with carb cleaner causes a rev up. If it does, that’s the source of the leak. Also chexk to see if your butterflies in the carb are working properly.
 
Help. This thing runs perfectly once I get out of that first gear acceleration. The hesitation initially is creating a safety issue in traffic. Plus, I have worked so hard through this Covid downtime to make it right. It is very frustrating.
 
accelerator pump. remove, clean and moisten the leather cup or replace. still available from toyota. been there done that
 
does it help to pull the choke out a bit?
could be a cracked intake?
 
I’m assuming all your emissions components are in place because you mentioned trying to pass. In the picture I’m posting, the vacuum line the vacuum gauge is plugged into, just plug it instead with a golf - T or a #1 size Phillips screw driver. The dotted line shows where you want to remove this line from the EGR valve. Drive it with it plugged like this and see if your flat spot is gone.
C46F1ED9-5C7B-4CA0-A67A-6ADFF6564C11.jpeg
 
Even with choke out, it falls a bit.
I will try the EGR today and see if I can check vacuum on Distributor.
What if EGR is the issue? Then what?
What if distributor is the issue? Then what?
 
spark plug and wires new. Passed smog, runs perfectly except for the initial fall. All new toyota oem vacuum lines. New distributor cap oem.
 

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