1984 GL Hitachi carb Duty solenoids chattering.

[oczuk32]

Got the wagon running after being parked for 13 years. Who knows why the duty solenoids are chattering. Who could explain the reason it's why the solenoids are doing that.

 

Edited 16 hours ago by oczuk32

[el_freddo]

I’ve never seen those devices before. Californian unit? We certainly didn’t get them in Australia! They almost sound like air pumps. 

Cheers 

Bennie

[bushytails]

That's normal operation.  The duty solenoids allow extra air to mix into the fuel in the emulsion tubes, leaning the mixture.  Off all the time, mixture is too rich and you get black smoke from the exhaust.  On all the time, mixture is too lean, you knock and can't go up hills.  The ECU varies the on/off duty cycle (hence the name) to adjust the fuel mixture in the middle of this range, until the oxygen sensor is happy, cycling just above and below stoichiometric.

 

 

[oczuk32]

2 hours ago, bushytails said:

That's normal operation.  The duty solenoids allow extra air to mix into the fuel in the emulsion tubes, leaning the mixture.  Off all the time, mixture is too rich and you get black smoke from the exhaust.  On all the time, mixture is too lean, you knock and can't go up hills.  The ECU varies the on/off duty cycle (hence the name) to adjust the fuel mixture in the middle of this range, until the oxygen sensor is happy, cycling just above and below stoichiometric.

 

 

I learn something new every time from you guys in this forum—really appreciate the insights. The solenoids are a bit noisy, and I initially assumed the ECU was causing the chatter or there was a bad connection. Interestingly, when I unplug them, the engine runs noticeably smoother. But when they’re connected, it feels like the engine is starving. I’m planning to clean the carb a bit more and take a closer look at the O₂ sensor. According to the manual, the solenoids operate based on readings from the O₂ sensor.

[oczuk32]

9 hours ago, el_freddo said:

I’ve never seen those devices before. Californian unit? We certainly didn’t get them in Australia! They almost sound like air pumps. 

Cheers 

Bennie

Yeah, it's all California emissions junk. I'm pretty sure it's robbing some horsepower. Honestly, it'd be way easier to slap on a Weber carb and call it a day. But I must comply with laws.