2003 GMC Envoy Repair Question
Vacuum fault. replaced gas cap without results. where do i start looking for a vacuum firstname.lastname@example.org
Finding a leak in this system is almost impossible without a smoke machine. You might be able to find one at an auto parts store that borrows or rents tools. It injects a white non-toxic smoke at 2 psi, then you search for where it's seeping out. The alternative is to hope to find something real obvious like a rusted-off hose clamp or dry-rotted hose. Other possibilities include a leaking purge valve or charcoal canister. There's nothing visual you can see with those types of leaks.
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