1987 chevrolet truck with tbi fuel injection

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

sounds like your fuel pump is bad. take your fuel pump off and then check it to see if it runs need good fuel pressure for the injectors to work right

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.

I would say more than likely your problem is a clogged fuel filter or a bad fuel pump. To narrow this down, listen for the fuel pump 'priming' (making a whining noise from the gas tank) turn the key to the On position and you should hear this whining for about 3 seconds, if you can hear this the fuel pump works fine, if not it is probably time for a new one. As for the fuel filter being that it is a 1987, I would replace it even if it is not clogged, the easiest way to test if it is clogged though is to blow at through it with your mouth and if you feel any resistance then it needs replacing.

yes, it could be a relay... you could also have a leak. Is the pump in the tank or outside the tank? if inside,. you may want to recheck your work..

first check fuel pressure with a mechanical fuel gauge that attaches to fuel line schrader valve. around T.B.I. if no pressure with key on check fuel pump relay for correct operation, and also the oil pressure switch has the fuel circuit to it so possible oil pressure switch also. fuel pump has a check valve to keep fuel from going back to tank, so when u turn key on fuel pressure should go up within 1-2 seconds on gauge. if fuel pressure goes down quickly, possible bad fuel check valve, change fuel pump and fuel pump check valve (located right above fuel pump inside tank)

1. IF HEAR PUMP RUNNING THEN ITS WORKING DO HAVE ENOUGH GAS IN TANK FOR THE PUMP TO PICK IT UP. MAYBE BLOW LINES OUT FROM TANK ONLY HAVE 1 PRESSURE LINE / RETURN LINE . SYSTEM WORKS BY BEING PRESSURIZED .MAKE SURE LINE HOOKED UP . IS IT FUEL INJECTED OR TBI

believe it or not some came with a fuse for the fuel, I would check that first, for both of your tanks to be bad , well its unlikely, I would say a fuse, and if its not that you should be able to turn your key on and kinda lean down under the truck and see if you can hear the pump working , if you dont hear the fule pump and the fuse is good the pumps are bad

The fuel pump should run a couple seconds when you turn the key on. The relay is on the firewall. There is also a fuel pump fuse (20 amp), on the firewall, make sure its good. The wire that comes out of the relay to the pump is either TAN/WHITE or PINK/BLACK. At the relay the ORANGE wire should be HOT , 12V at all times.

First off, I'm a great believer in the simple solution. If jumping the relay works, then replace the relay.

As far as a relationship between fuel pump operation and oil pressure, coincidence of operation.

If the new relay fails you, I'll need some more info:

• Fuel Injected? If you turn the key on (not to start) do you hear the fuel pump come on for a sec then shut off?
• Hard to start when hot, cold, doesn't matter
• When it does start, does it idle ok? erratically? High? Won't stay running? Dies immediately?
  
• Does it blow smoke? Black? Blue? White?
• When driving, does it lack power? Stumble? Stall?

Hope it's the relay

Mike