Car bucking / choking when cold at low RPM (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Jan 5, 2016
Threads
36
Messages
205
Location
Canada
Trying to debug a low-RPM bucking that happens when the car is cold (I have an 80, but with the 1FZ-F engine). I don't have a lot of experience with carburetted engines, so I'm not really sure where to look. I read this thread, but feel like my issue is maybe a little different as I never moved the car between altitudes? Basically, this is what happens: when the car starts cold, it idles and runs fine, but when you row through the first 2-3 gears, it will almost invariably buck and almost stall if the RPMs are around 1,000 or less; giving gas at that moment does not seem to help too much, just need momentum to push through that specific moment, and then it's fine. Once warmed up, it's mostly fine - occasionally it'll hiccup at similar RPMs, but nothing quite as serious, no danger of stalling.

I'm thinking fuel starvation right at that moment, but how do I debug this - is this a carb problem or a fuel pump problem? Long-term plan is maybe to throw on a Holey EFI kit, but I just want it running perfect for now, and figure that part out later.

Thanks for any advice!
 
attached is the excerpt from the toyota manual with some information about the carburetor. If this were an FJ60 you symptoms may indicate something wrong with your fuel cut solenoid, but I'm not sure why that would only happen when the engine is cold. There are not specific test for this solenoid in the manual but you want to make sure it is open when the ignition is on. Maybe check wires, etc for good connections.

You can check the fuel level through the sight glass on the front. It's a pain to hop out of your car and pop the hood in the middle of the road, but circumstances may present themselves where you can check this.

Otherwise look at the choke tests. There is an automatic choke (maybe it is opening too soon) but also a choke breaker and fast idle cam breaker that may not be working properly.

Good luck.
 

Attachments

  • 1FZ-F carburetor Description.pdf
    272.6 KB · Views: 38

Users who are viewing this thread

Back
Top Bottom