If you hang out on the 60-series forum, you've already seen this. If not, any thoughts would be appreciated.
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My 60 will not idle when I come to a stop. The engine RPM drops down to ~300 and stumbles, eventually dying. It runs fine when I give it some gas or when I'm moving but at startup and after the engine is warm, it simply won't idle. Occasionally, it will 'remember' how it's supposed to run, but not very often. 2 years ago I had the same symptoms which turned out to be massive vacuum leaks at the intake manifold and the bottom of the carburetor. It's not that this time. I've gone over all the vacuum lines and not found any hoses that are cracked or disconnected. I think I've found the problem but won't know until I replace the part. The Main Diaphragm in the Distrubutor Vacuum Advancer doesn't hold vacuum. Therefore, not only do I have a vacuum leak but the vacuum advance feature is not functioning. I've ordered the part from Dan. The only thing that is confusing to me is that the BVSV that provides the vacuum to the Main Diaphragm is not supposed to open until the coolant temperature is above 44C, according to my Emission Control Manual. So I shouldn't get vacuum leak problems from the bad diaphragm right at startup because the coolant hasn't caused the BVSV to open yet. Of course, this is a 20 year old truck with 265,000 miles so that could be stuck open. When I get the Vacuum Advancer in, I'm going to replace it and also replace all the vacuum hoses. Maybe I'll get lucky.
Does anyone have any thoughts on this or had a similar experience?
Marc
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My 60 will not idle when I come to a stop. The engine RPM drops down to ~300 and stumbles, eventually dying. It runs fine when I give it some gas or when I'm moving but at startup and after the engine is warm, it simply won't idle. Occasionally, it will 'remember' how it's supposed to run, but not very often. 2 years ago I had the same symptoms which turned out to be massive vacuum leaks at the intake manifold and the bottom of the carburetor. It's not that this time. I've gone over all the vacuum lines and not found any hoses that are cracked or disconnected. I think I've found the problem but won't know until I replace the part. The Main Diaphragm in the Distrubutor Vacuum Advancer doesn't hold vacuum. Therefore, not only do I have a vacuum leak but the vacuum advance feature is not functioning. I've ordered the part from Dan. The only thing that is confusing to me is that the BVSV that provides the vacuum to the Main Diaphragm is not supposed to open until the coolant temperature is above 44C, according to my Emission Control Manual. So I shouldn't get vacuum leak problems from the bad diaphragm right at startup because the coolant hasn't caused the BVSV to open yet. Of course, this is a 20 year old truck with 265,000 miles so that could be stuck open. When I get the Vacuum Advancer in, I'm going to replace it and also replace all the vacuum hoses. Maybe I'll get lucky.
Does anyone have any thoughts on this or had a similar experience?
Marc
