87 5.0 Tpi W/ Stalling Problems

[87Z28_5.0TPI]

I have an 87 camaro Z28 with a 5.0 TPI that has issues with stalling. I just read in the Chilton manual that "EVAP" system can cause this. My son noticed gas leaking from the canister recently, so I assume that the EVAP system may be the fault. The car has about 180-K miles and runs great at times, it just wants to stall. I don't think it's an electrical problem because we have ruled out or replaced most of the electrical system. I have noticed the smell of gas when riding in the car as well. With no codes to indicate this as the culprit, what is the chance that the EVAP system is the fault?

[Blue Bowtie]

If you're smelling raw fuel, there is a chance that the EVAP canister is not purging properly and is saturated. There is a remote chance that the EVAP is not purging because it is clogged. You may want to check the filter pad on the underside of the canister. 1987 was about the last year the canister was equipped with a replacement filter. If the filter is clogged, teh canister cannot purge properly even if the system works otherwise.



That may cure the raw fuel aroma, but usually even a clooged EVAP won't cause stalling.

Another potential cause of both the raw fuel and stalling, as well as hard starting after heat soak, is a leaking fuel pressure regulator. If the FPR diaphragm has ruptured, raw fuel will be pumped into the intake plenum through the vacuum hose connected to it. This is easy to diagnose by simply disconnecting the vacuum hose for the FPR while the engine is running. If there is raw fuel present at the hose, the FPR is leaking. There are two vacuum hoses connected to the right side of the plenum, adjacent to the fuel pressure test port (Schrader valve). The front of these two hoses should be for the FPR.



There are several other possibilities, including weak ignition, poor injector performance, IAC valve malfunctioning, and others.

Check those two items first, and see if there are any results.