MC2100 wont idle sucking air hard
richardoutwest
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- Location
- Southern Arizona
- Vehicle(s)
- 76 CJ5 304 all stock T-150 D20 4.10 gears
76 AMC 304 no power brakes completely stock with modular ignition upgrade (stock Motorcraft upgrade) electric choke....
1) This is a high dollar rebuild MC2100 carb I bought last year. I put the 1.08 on and took the 1.21 off and the jeep ran great, 10 times better than the 1.21. After about a month the jeep acted like it was loading up and had a hard time getting it home, used a ton of gas!
2) Did not have time to mess around with it so I put the 1.21 back on and the jeep ran like it did when it was on originally when it was on so I have ran it for the last year.
3) put the 1.08 back on and check all the adjustments, float level ect. Ran great again for about a week and now wont idle again unless you have the gas on a little.
4) Butterfly is pulled wide open. Pulled the top cover off the carb and fuel level was good, right where the the float was adjusted (9/16" below top). Sprayed starter fluid around the carb with no luck checking for vacume leaking.
This to me sounds like a small vacume leak because it will run off idle, but I can not find it. When I put either carb on it pulls 18 inches of vac off the manifold with vac advance plugged. 18 is all I have ever been able to get out of this old motor.
Since I can put the 1.21 on and it will run with no problems, I dont think the fuel pump is the problem or the fuel filter or the PCV. It seems to be in the carb itself. I dont think it is the power valve since the problem is at idle?
Should I pull the carb off and blow out all the venturies? ANY input guys?
1) This is a high dollar rebuild MC2100 carb I bought last year. I put the 1.08 on and took the 1.21 off and the jeep ran great, 10 times better than the 1.21. After about a month the jeep acted like it was loading up and had a hard time getting it home, used a ton of gas!
2) Did not have time to mess around with it so I put the 1.21 back on and the jeep ran like it did when it was on originally when it was on so I have ran it for the last year.
3) put the 1.08 back on and check all the adjustments, float level ect. Ran great again for about a week and now wont idle again unless you have the gas on a little.
4) Butterfly is pulled wide open. Pulled the top cover off the carb and fuel level was good, right where the the float was adjusted (9/16" below top). Sprayed starter fluid around the carb with no luck checking for vacume leaking.
This to me sounds like a small vacume leak because it will run off idle, but I can not find it. When I put either carb on it pulls 18 inches of vac off the manifold with vac advance plugged. 18 is all I have ever been able to get out of this old motor.
Since I can put the 1.21 on and it will run with no problems, I dont think the fuel pump is the problem or the fuel filter or the PCV. It seems to be in the carb itself. I dont think it is the power valve since the problem is at idle?
Should I pull the carb off and blow out all the venturies? ANY input guys?
