fj40 idling problems

[Vernon]

Hi all, '73 fj40 that is all stock. When driving down hill or at higher speeds and I let off of the gas, their is a popping/backfiring out of the exhaust pipe. After the popping, the engine will not idle and it dies, unless I keep feathering the gas pedal.
Any ideas about what is wrong are appreciated. Thanks in advance.

I still can't figure this out... Help!

 

[FF LC FREAK]

Mine does this occasionally, also. To me, it is an indicator that I need to adjust my carb and valves. A little tune up work pretty much makes it go away. If you have any questions about tuning your carb or adjusting your valve lash, just post up or look in the FAQs. There are plenty of write ups on both of these procedures.

Good luck!

 

[vk7ybi]

Blocked idle circuit..

 

[Pin_Head]

Idle fuel mix is too lean to ignite by spark leading to its detonation in the exhaust manifold. It is either a plugged/misadjusted idle circuit or if it is a smog carb, the throttle positioner is missing or non functional.

 

[Mr. Toad]

Blocked idle circuit..

Idle fuel mix is too lean to ignite by spark leading to its detonation in the exhaust manifold. It is either a plugged/misadjusted idle circuit or if it is a smog carb, the throttle positioner is missing or non functional.

x2.

Make sure the idle solenoid is working too.

 

[Vernon]

thanks for all the responses. the T/P has good movement and vacuum when I disconnect the hose to it? Does this mean that it is working properly?

 

[Pin_Head]

thanks for all the responses. the T/P has good movement and vacuum when I disconnect the hose to it? Does this mean that it is working properly?

Not necessarily. It needs to lose the vacuum at speeds above 15 MPH to function properly.

 

[Vernon]

What is the best way to test the T/P to see if it loses the vacuum above 15MPH?

 

[Pin_Head]

You put a vacuum gauge on the line and drive at greater than 15 MPH.