Third Generation F-Body Message Boards

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- TBI (https://www.thirdgen.org/forums/tbi/)

- - No fuel! (https://www.thirdgen.org/forums/tbi/759531-no-fuel.html)

Cranks but no fuel. Replaced relay,fuel pump, oil pressure sensor still nothing. Is there any other sensor that could cut fuel in any way on a 1991 RS 305 tbi? Rear impact sensor?

Vats, no injector pulse ?

Original TBI injectors?

Quote:

Originally Posted by Jesse Mortensen (Post 6286873)

Cranks but no fuel. Replaced relay,fuel pump, oil pressure sensor still nothing. Is there any other sensor that could cut fuel in any way on a 1991 RS 305 tbi?

1. Does the fuel pump run for two seconds when the key is turned from "off" to "run"? If the fuel pump primes, it's not the fuel pump relay. If the pump runs when the engine is being cranked (has oil pressure) it's not the oil pressure switch.

2. Do you have spark? No fuel, no spark = distributor or wire harness problem. ECM requires distributor pulses to turn on the fuel injectors. No pulses, no fuel spray.

Can't hear the fuel pump run or prime. I've got spark. What is the sensor on The back of the rear end pumpkin? This problem happened driving on a hot day on the freeway. Just lost all fuel all of a sudden. Replaced the fuel pump then ran good for 1 1/2 hour drive then lost all fuel again.

Quote:

Originally Posted by Jesse Mortensen (Post 6287218)

Can't hear the fuel pump run or prime.

What is the voltage on the fuel pump + wire near the fuel tank when the engine is cranking? Should be within a couple of volts of battery voltage
What is the voltage on the fuel pump - wire near the fuel tank? Should be less than 2 volts, less is better.

Quote:

Originally Posted by Jesse Mortensen (Post 6287218)

I've got spark.

Have someone crank the engine while you listen to the injectors. You should hear them clicking. (They won't spray fuel if there's no fuel pressure.)

Quote:

Originally Posted by Jesse Mortensen (Post 6287218)

What is the sensor on The back of the rear end pumpkin?

No idea. Sure you're not seeing the brake plumbing, or the axle vent?

Quote:

Originally Posted by Jesse Mortensen (Post 6287218)

This problem happened driving on a hot day on the freeway. Just lost all fuel all of a sudden. Replaced the fuel pump then ran good for 1 1/2 hour drive then lost all fuel again.

Did you replace the short wire harness from the fuel pump to the fuel pump hanger connector? They're known for corrosion.

I figure it's most likely you have a bad wire--corroded connection, broken, pinched, something like that--between the engine compartment and the fuel pump--or between the fuel pump and ground. 'Course, it could just be a plain ol' defective pump. If it was a plugged filter or filter sock, you'd hear the pump run during "prime".

There is a plug riveted behind the backseats under the carpet and it plugs in underneath the car above the rear end. Plug-in runs up to the fuel tank is this a sensor or just a connection point?

The riveted connector is just a body pass through connector. No spliced in this connector. The pump power/ground and gauge sender connector is located by the tank.
Are you not getting power through C100 to the pump ?

Can I access any fuel tank/gauge wire’s from underneath?

Yes, It’s next to the tank. A 3 wire connector.