cordoch

Hi Guys, I have an 86 PU in California with a 22R, carb, O2 sensor. It runs very poorly when cold. Burns rich, misses and sputters. It is much better when warm, but still looses some power and stumbles if not at high RPM, especially on hills. I have 3 ideas, bad O2 sensor, stuck EGR, and/or bad diaphram in AAP. Coolant and oil are always full. It has new plugs and wires. Does anyone have any similiar experiences or ideas to avoid replacing a working component ? Thanks!

Silver-munkie

I'm having the same problems right now. Looking forward to any help/suggestions that can be offered. Thanks guys. In addition to the symptoms above mine is also burning a pretty fair amount of oil.

cordoch

I pulled off the EGR (head) and the tube (manifold), both were relatively clean. The EGR was working correctly. The vacuum hose to the AAP was full of gas, so the diaphram is likely bad. A vacuum prong on the BVSV to the rear of the carb, choke area, was broken. This looks like a hard item to remove, maybe use a crows foot wrench? Does anyone know the size of the fitting? It looks like it is in the 17-19mm range. Thanks!

slow-mo

Well, at a cold engine start up, the computer ignores the O2 sensor until the engine coolant reaches operating temperature, a.k.a. "closed loop".



If you don't know already, this is the valve that controls both the AAP and the Choke Opener.

In the pictures below, the BVSV is labeled as TVSV. It serves the same function.








I replaced mine several years back, and I do believe your correct in that millimeter size range. I don't remember specifically, though. I had my carburetor off when I did mine, so I just used a regular open-end wrench.

cordoch

Thanks Slo-Mo, the BVSV and fast idle choke diagrams are very useful. After I replaced the AAP diaphram (I used the Walker Product Carb kit from O'Reilly, P/N 15827A), the truck runs very well now. I still have the broken top prong on the BVSV going to the choke pull off/ fast idle. This will be replaced soon and the AAP diaphram was the major problem. I decided to buy the carb entire kit as a complete rebuild is in the future. If anyone wants just the AAP diaphram, NAPA has it as part # 24014 for about $19.00. Thanks for all the help!