Rod S said:
AS always its a test and isolate deal where your forced to test the function of components to verify each until you find the faulty component,the TPI efi fuel injection system, was on chevy engines from 1985-1991-it was designed to run on 37-42 psi fuel pressure the fuel pump should provide a minimum of 42 psi and the fuel pressure regulator should limit the max fuel pressure to no more than 42 psi at the fuel rail, feeding the injectors.
since you didn,t mention the intermittent power loss was related to rpms or when the car gets hot or enters some gear, Im thinking its a fuel delivery issue, or a bad electrical connection,since its not the original car you may not be able to pull trouble codes, but you can still test and use a multi meter and test sensors ,grounds and fuses and fuel pressure, and voltage.
its a good idea to change the fuel filter when you have issues with fuel delivery as a first step as a dirty or clogged fuel filter is a common problem, Id also suggest installing a better than stock fuel filter that separates water from fuel, as crap contaminated fuel is common, something like this, filter pictured, mounted near the tank,but one rated to handle the pressure and flow rates required would be ideal,
rather than the crappy stock filter,
most TPI systems use an in tank fuel pump that is cooled by sloshing fuel and it must be located low in the tank to work efficiently.
obviously if the fuel level in the fuel tank won,t keep the fuel pump intake constantly covered your going to have issues with the pump occasionally sucking air, vs fuel,
a very common issue with older TPI fuel systems is related to the fuel pressure regulator,internal diaphragm leaking, thus the pressure falls off and the engine stalls ,if the oil pressure drops below 4 psi the oil pressure safety switch cuts power to the fuel pump,
if the fuel pump relay lost power the pump shuts off , theres tests and diagrams in the links the links below will provide the required diagnostics, bad grounds, blown fuses, defective or clogged injectors and loose injector electrical connectors are all suspect, but fairly easy to test and isolate and cure once located.
related info
http://members.shaw.ca/corvette86/FuelS ... gnosis.pdf
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