carb issues

[alson81]

Hi guys. This is probably a good question for Gerry P. I replaced my ecm on my 81 because it was flashing repeatedly and showing no codes. Since i gave changed it codes have been present including o2 sensor and m/c solenoid. I had an problem with the mc solenoid before only to find out the previous owner had connected the test wire for the dwell to the choke therefore it was grounded and wasn't cycling. The mc solenoid worked fine after it i changed the wires around. Then i replaced my ecm and the mc solenoid stopped working. I sent my carb back to the rebuilders and got a new mc solenoid. I put the carb back on this weekend and the mc solenoid still doesn't work. Is there a signal from the o2 sensor to make the solenoid cycle or what are your thoughts?
Thx Al

 

[Antz81]

You'll need to sort out the O2 sensor before you start checking to see if the m/c solenoid is working.
If the O2 sensor hasn't been replaced in a while that's probably all it needs.

 

[Peer81]

You can test the mc solenoid by connecting it very briefly to a 9v battery. You can hear it activate or put a tiny screwdriver down the fuelbowl venthole on the plunger and you can see it go up and down. Then you know for sure the solenoid is working.

Then i think you can short circuit the o2 connector and see if it runs (in open mode). I don't remember that resistance the o2 sensor needs to be at 80F but if it's an old one just replace it.
Good luck!

Greetings Peter

 

[alson81]

Thx Guys i will replace the o2 sensor first and go from there
Cheers Al2

 

[alson81]

Hi Guys i replaced the o2 sensor today which took the code away but still the M/C solenoid is not operating. As i said previously that is was working before i changed theECM. I tested the #18 Terminal back at the ecm and there is 12 volts. I checked fhe continuity of the wire between the ecm and plug for the m/c solenoid and it's good. What baffles me is when you ground the diagnostics test terminal the #12 code flashes but also the m/c solenoid cycles continously. I think i got a bad new ecm. Let me know what your thoughts are.
Thx Al

 

[Antz81]

Hi Guys i replaced the o2 sensor today which took the code away but still the M/C solenoid is not operating. As i said previously that is was working before i changed theECM. I tested the #18 Terminal back at the ecm and there is 12 volts. I checked fhe continuity of the wire between the ecm and plug for the m/c solenoid and it's good. What baffles me is when you ground the diagnostics test terminal the #12 code flashes but also the m/c solenoid cycles continously. I think i got a bad new ecm. Let me know what your thoughts are.
Thx Al

How do you know it's not working?
it does cycle when the test terminal is grounded. That's normal

 

[alson81]

It is my understanding that when you turn the key forward it turns on and makes the fluttering noise continuously. Or doesn't it?.
Thx Al

 

[Antz81]

It is my understanding that when you turn the key forward it turns on and makes the fluttering noise continuously. Or doesn't it?.
Thx Al

Only if the test terminal is grounded. Or if you start the motor.
easiest way to check would be to stert the motor and connect a dwell meter or place a paper clip down the vent to see if it's moving.