QuestionI have a 1990 Chevrolet Suburban with the 454 V8 and TBI Fuel Injection System. I was driving home from church and the engine just stopped dead. The engine turns over just as it is supposed to. The rotor, cap, spark plugs, wires and air filter are new and fully functional (fully checked electrically and the engine tries to run if fuel is applied) what appears to be lacking is fuel (no fuel being sent out of the injector nozzles)and I don't hear the pump energizing or sending fuel when I disconnect the fuel line at the filter and run fuel through a tube into a pan. The fuel pump, in tank fuel filter and in line fuel filter is brand new and functional when I tested it outside of the fuel tank and after installation into the tank. The fuel pump relay is brand new and I hear it "click" when I put the ignition switch into the "run" position. I measure 8.7 volts being delivered to the fuel pump. HELP PLEASE. What else could it be? Thank you in advance for any advice or suggestions you can provide.
AnswerHi Greg,
That 8.7 volts is the problem.
The pump needs battery voltage.
Are you sure it is the wire to the pump that you are measuring? The fuel gauge sender wire is in the same connector, as well as the ground wire.
Make sure the ground wire is making good connection, both in the connector, and at the frame. That is all the ground the pump gets, and it needs to be good.
Then measure the third wire in the plug. Remember it will only be hot for two seconds, unless the engine is being cranked.
There is also an oil pressure switch that supplies battery voltage to the fuel pump as long as the oil pressure is above 4PSI, so I sincerely doubt that the relay is the problem, since the oil switch would have been closed when you were driving.
So I would look for the fuel pump fuse, which could be a fusible link.
One of the larger wires to the relay should be hot at all times. It is the one that supplies the battery power.
A smaller wire energizes the relay, and it would click, whether the big wire had power or not.
Van
