max_boost951

'86 951 fuel cutoff around 4000 RPM. Suspected FPR, pulled vacuum line and no leaking fuel present. Pulled vacuum line of the fuel pressure damper and there is a little bit of rust on inside of the vacuum port. Pulled a vacuum on the Damper and little bit of rust in the vacuum pump line.

Question: Can the fuel damper possibly fail half-way? I pull the vacuum hose of the regulator and the fuel pressure increases maybe 3 psi, so I pinched the return line to where rail pressure was 65 psi and the car ran better. Maybe the diaphragm in the damper partially seized not allowing enough fuel by?

NEW: Fuel filter and fuel pump (Failure), plugs, cap and rotor, Coil (Exploded), KLR box (spare), no cyclic valve due to MBC w/ Dual port Wastegate

ITEMS I'VE CHECKED: Knock sensor (297 Kohms), DME temp. sensor, TPS ( no breaks in the ohm check), Vacuum lines , Ohm checked Injectors

Please help!!! Getting passed by crap cars cause have no WOT!!!!

schip43

Check for boost leaks also, you did not say anything about a sound like a waterfall, however 4000 rpm was where my throttle body to IC pipe was popping off at.