1987 Chevy S10 TBI 4cyl 2.5 L will not run. I changed a weak fuel pump and i am now getting good pressure. I swapped ecm's, changed fuel pressure switch, oil pressure switch, distrib, rotor, electronic piece on distrib, map sensor and o2 regulator. I check fuel pressure to the throttle bottle and it is gettting fuel. For some reason the fuel injector is not spraying fuel. Engine runs fine if spraying starter fluid inside but cuts off after u stop spraying.

Need to connect a fuel pressure gauge and see if you are getting sufficient pressure to the tbi

1986 chevy s10 2.5l no gas coming from injector. - S-10 Forum

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Sep 2, 2009 - 24 posts - ‎7 authors I have no gas coming from my injector it a 1986 chevy s10 2.5l I have replaced the fuel pump,oil pressure switch & I checked and oil would ...

Kent, That sounds like normal operation.....see this link (https://www.justanswer.com/chevy/0z9bu-fuel-pump-relay-located-1987-chevy-silverado.html) The ECM shuts the pump down if the engine doesn't begin running in two seconds. I would bleed out the fuel line up to the TBI...crack the line at the TBI then cycle the key a couple of times until you see gas coming out of the line at the TBI. That will ensure you have fuel at the TBI, then try to start the engine. See the link for additional info.

Check the fuel pressure at the shredder valve, you should have 13 to 13.5psi, anything other then that will give you problems in the GM TBI. If the pressure is bad, then you may have to replace the fuel pressure regulator at the bottom of the TB. 
Good luck and keep me posted. 

relace the throtle air idle valve.The temp switch will allso cause this problem.

Check the trottle body postioning sensor...

you have to reset base idle see manual at library for procedure

That eliminates the crankshaft and camshaft position sensors. Have you checked the fuel injector itself for an open winding or stuck valve plunger? There should not be a steady 12 volts to the injector--if good injector, it would be spraying fuel steadily into the throttle body. But at least the engine should try to run if poorly. Take the injector out, dry it off with air, and intermittently apply 12 volts to one terminal while grounding the other. You should hear a click from inside every time you touch 12 volts. If not, replace it. If it does, it may be plugged with debris. Try blowing through it in reverse with compressed air.

It does sound like a fuel problem, try running some jet cleaner through as you may have clogged jets. Sometimes, removal of air filter and placing the palm of your hand over the top of the carb's butterfly valve, will clear blocked jets when engine cranked over a couple of turns.
Also check the float valve is letting fuel in, could be stuck.
I hope this helps.

The problem is fuel related. Disconnect the fuel line to see if fuel is reaching the carb.