Fuel Pump diagnosis

[Gene13]

Can anyone tell me if the fuel pump should turn on (and make an audible sound), to charge the fuel line, when the ignition is turned on (but before actually engaging the starter) ???

It's a 1996 Camry v6.

Any help would be appreciated.

Thanks in advance.

[new echo owner]

It shouldn't run unless it sees a crank signal to power the circuit open relay which powers the fuel pump, and after the engine is running the ECM takes over powering the relay.

What kind of sound is it making?

N.E.O.

[Gene13]

not making any sound. when I apply 12v to the pump motor, it runs. when I check the voltage at the harness connector I get 10.73.

so at this point it does not look like a pump motor problem.

[new echo owner]

What are you trying to repair anyway? No start or ? Where did you check to get the 10.73 reading, at the connector at the pump?

N.E.O.

[Gene13]

before I forget, which I am good at . . . Thanks for the return posts and the help.

Car won't start, cranks fine, trouble began last night. Got it started after about an hour, got it home then this morning wouldn't start again.

I pulled the fuel pump and tested just the pump motor using a 12vdc power supply, it spins up fine. then put it back in the sub assembly and applied the 12vdc at the terminals of the connector and it spun up fine again. Then I put my Fluke meter across the connector coming to the fuel pump and it had about 10.75vdc.

So, that's where I'm at right now.

But I did see in the Chilton's book for the 1MZ engine that I have to test the resistance of the motor instead of what I did. I will do that tomorrow.

But aside from that, any other ideas???

[new echo owner]

At the diagnostic connector in the engine compartment, there is a terminal 'Fp' and 'B+', jumper those two terminals while cranking see if the start. Have you check the fuel pressure?

Out of curiosity, why do you suspect the fuel pump being the cause of your no start problem?

N.E.O.

[Gene13]

not sure, i think because it is a key factor and I have had fuel pump problems with other cars. after doing some research, though, I need to be sure the crank sensor is good by seeing if the tach moves while cranking (you would think I would have noticed that), then check spark and then I want to take the hoses off of the fuel pump and see if it actually pumps gas (though another hose into a basin)

beyond that maybe drive it into the lake :-)

[new echo owner]

If you haven't check yet, is the check engine light on when you turn the key on? Since that is one of the first indication of whether the ECM is getting power or not. Have you check to see if there is any code in the system? If there is a sensor that is not functioning, it may store a code in the memory, which will help your diagnoses. Unfortunately, for a 96' you do need a scanner since it is OBDII.

N.E.O.

[Gene13]

"check engine" light comes on and when cranking stays on and then stays on when key is in the "on" position. does this in itself mean there is a code logged, or does the engine have to start for the "check engine" light to go out?

also, the tach does not move when cranking. this may indicate the "crankshaft position sensor" is bad. from what i understand without a signal from the "crankshaft position sensor" the ECM will not issue the "spark" command. does that sound right?

is there a test for the sensor that can be done without pulling the wheel and getting under the car?

[new echo owner]

Usually the CEL will go out when the engine is running and no fail code set in the ECM memory. It won't hurt checking to see if there is any code store; however, as I had mentioned, you do need a scanner for 1996 OBDII system.

If it is the Crank Position Sensor, you do need to at least take the splash shield off from the right side of the car with the steering turned to the right to gain access to the sensor itself. Or you can locate the terminal at the ECM to check for input.

And you are correct, without the CPS input, the ECM doesn't where the engine is at or how fast, or if the engine is turning over. So in a sense it is lost. It needs both the Cam Position Sensor and Crank Position Sensor inputs to establish spark control to switch on and off the ignition signals.

N.E.O.

[Gene13]

borrowed a scanner and the only code in memory was for the Crankshaft Position sensor. I also used the scanner to monitor real time data and there was 0 rpm while cranking (CPS not functioning). I have one on order for tomorrow, will replace and let you know.

[new echo owner]

Originally Posted by Gene13

borrowed a scanner and the only code in memory was for the Crankshaft Position sensor. I also used the scanner to monitor real time data and there was 0 rpm while cranking (CPS not functioning). I have one on order for tomorrow, will replace and let you know.

Good, keep us posted.

N.E.O.

[Gene13]

Replaced the Crankshaft Position sensor and that was the fix!

N.E.O. - Thanks for helping me out, I appreciate it.

[new echo owner]

Glad to hear that you have it going again.

Enjoy your ride and drive safe.

N.E.O.