OS 7L Carb Problem?
06-29-2003 | 02:34 PM
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From: Carol Stream, IL
OS 7L Carb Problem?
I picked up a .61 SF ABC that appeared to be in pretty good shape. It was sitting on a shelf in someone's basement for years.
Here's my problem.
The engine won't idle. It looks like it isn't pulling fuel below half throttle. If I open the throttle wide and prime the engine, it
starts on the second flip at 1/8th throttle. It runs for 10 seconds and dies. I pulled the 7L carb and carefully disassembled it on the bench, looking for dirt or other problems. Nothing noted. One thing bothers me. The opening in the spray bar doesn't look right. If you look at it through the bottom, there isn'y much of an opening and the shutter it rotates in is covering half of the fuel opening. I have very little experience with this old motor and I need help. A new carb is more that I paid for the engine.
Here's my problem.
The engine won't idle. It looks like it isn't pulling fuel below half throttle. If I open the throttle wide and prime the engine, it
starts on the second flip at 1/8th throttle. It runs for 10 seconds and dies. I pulled the 7L carb and carefully disassembled it on the bench, looking for dirt or other problems. Nothing noted. One thing bothers me. The opening in the spray bar doesn't look right. If you look at it through the bottom, there isn'y much of an opening and the shutter it rotates in is covering half of the fuel opening. I have very little experience with this old motor and I need help. A new carb is more that I paid for the engine.
06-30-2003 | 02:41 PM
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OS 7L Carb Problem?
If the carb had been previously disassembled, the idle mixture control valve may have been installed incorrectly. This is the part that has the U-shaped yoke bolted to it. The idle mixture control valve should have the slot facing forward.
The part that goes into the throttle barrel is keyed in place with a small pin. That peice cannot be installed incorrectly.
The part that goes into the throttle barrel is keyed in place with a small pin. That peice cannot be installed incorrectly.
07-13-2004 | 10:21 PM
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From: Kalamazoo,
MI
RE: OS 7L Carb Problem?
Sunflyer-
This information maybe too late to help you but I found out something about this carb that I think has been missed. Specifically, the U-shape yoke that is bolted to the idle mixture control valve can be attached too different ways. One way and the engine barely runs, flip it over and the engine will run fine. I had the same trouble you did, and even cleaned out the carb. After reassembly, it ran no better. I took the carb off and looked at it from the bottom. I discovered that the slot in the spray bar was only seen when the carb barrel was wide open, but vanished before the barrel was 20% closed. At first I thought the carb was manufactured wrong. That's when I took off the yoke and noticed that the connecting slot is not symmetrical with the yoke. I flipped the yoke over, reconnected it, and now the engine runs perfectly. Hopefully, you can use this information. If not, there maybe others that this information will help.
Don Myer, Kalamazoo, MI
This information maybe too late to help you but I found out something about this carb that I think has been missed. Specifically, the U-shape yoke that is bolted to the idle mixture control valve can be attached too different ways. One way and the engine barely runs, flip it over and the engine will run fine. I had the same trouble you did, and even cleaned out the carb. After reassembly, it ran no better. I took the carb off and looked at it from the bottom. I discovered that the slot in the spray bar was only seen when the carb barrel was wide open, but vanished before the barrel was 20% closed. At first I thought the carb was manufactured wrong. That's when I took off the yoke and noticed that the connecting slot is not symmetrical with the yoke. I flipped the yoke over, reconnected it, and now the engine runs perfectly. Hopefully, you can use this information. If not, there maybe others that this information will help.
Don Myer, Kalamazoo, MI
