1987 chevy engine problem

didnt specify year model or engine --generic answer --if the tbi is flooding ---check the fuel pressure regulator --and the tbi itself

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

First, make absolutely sure the fuel pump is running when the key is on and is pushing fuel to the TBI. Take the feed line off the TBI if you have to. Watch it, fuel will spray everywhere if you aren't careful. Most fuel pump "no run" problems are caused by a bad ground. Use a VOM to check for power and ground.

Make sure the injectors receive power when the engine is cranking to start. Might be something as simple as a blown fuse. Can check with a noid light or 12v test light. Remote possibility of the injectors losing power when via the ignition switch and/or wiring when you crank the engine.

Fuel pressure regulator may be defective. TBI must be disassembled to replace it. There is a nice aftermarket adjustable regulator available.

Internal to the TBI itself (SOME, BUT NOT ALL HAD THIS) is a small neoprene pressure bleed. It has a VERY small hole in it, used to slowly bleed off the fuel pump pressure when the engine is shut down. If the diaphragm ruptured the fuel will return to the tank, never building enough pressure to spray out the injectors.

These units are relatively easy to rebuild. Youtube has several good vids walking you thru the process if you have any doubts.

bad harness connection
faulty pump relay
faulty pressure reulator
blocked filter
no signal from ECM to relay

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 Static Fuel Pressure engine off , Should be about 10 to 13 psi this will determine if Fuel Pressure Regulator is faulty , if pressure is bleeding off it will be hard starting... If you find a bad regulator then replace it with new... Bleed pressure off by removing fuel tank filler cap and by releiveing it at the fuel rail before the TBI unit....

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

Check the trottle body postioning sensor...

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.

Check the injector for 12v on one wire. if good check the other wire for a ground witth the key on. The ground wire pulses from the ECM If you dont have 12v from one wire to the other but you have 12v from one wire to battery ground then be sure the ground wire is good to the computer. If you don't have 12 v at any time check for open hot wire or bad fuse. ADD 12v to the hot wire at the injector. DO NOT add to the wrong wire or you will fry the computer