mj1pate

this is another post that aggregates topics from a few more recent posts concerning fuel tank implosions/collapses, fuel pumps that buzz, even after replacing old with new, plus a presentation on arachnids

I replaced my fuel pump after the original began buzzing. The buzzing intermittently resumes with the new pump, usually stopping after filling the tank. Others have remarked that their tanks imploded after buzzing had continued over time, with the suspect cause being negative (vacuum) pressure, as the vapor recovery system sucks vapor from the tank, and the tank doesnt ever recover normal pressure.

So as concerns my 86.5; the PET has incomplete diagrams for my model year, as illustrated below. The most notable absence is the specifics for how tank venting is accomplished by way of the charcoal canister. The 87 model year has a (probably cheaper) version of the same architecture, and PET shows the complete vent routing, as below.

Something is getting in the way of tank venting in many of our machines. My 86 has a fairly new charcoal canister and new hoses. I suspect that what may be happening to clog things up is the same phenomenon happening to many vehicles:
http://www.reuters.com/article/us-au...A3315G20140404

I haven't validated that my tank vent issue is a result of arachnid invasion, and will be checking this out this weekend. I would just suggest to trace a clear path thru your vent lines from the canister for any obstacles.

ammonman

Item 16 in the 86.5 PET diagram connects to the fuel tank rollover check valve. If the tank bursts then fault could be in the rollover check being clogged or stuck closed, several combinations of vapor lines and/or vacuum control valves clogged or stuck shushalong with the canister being clogged. I suspect that collapse occurs when the canister is clogged and the two vacuum control valves are failed open. This would allow the fuel tank to be exposed to manifold vacuum at all times. An idling engine creates 15"-18" of vacuum and if there isn't a way for the vapor system to allow air in the engine vacuum could cause collapse of the tank. I doubt simple pumping of fuel out if the tank would create the required level of vacuum needed to cause collapse.

Mike