MPI/Fuel problem. Need help

[Golden GSX]

Hi everybody,
long story short, My fuel pump isn't turning on
anymore.
I checked the MPI relay and everything was fine but
when I plugged it back in and turned on the ignition I
still wasn't getting any voltage on the black/green
wire. (the wire that turns into the black/white wire
at the pump, pin 2 on the relay harness)(correct me if
I'm wrong)
If anyone has any ideas on what might be wrong or any
suggestions, please reply.
besides that issue, is it okay to run +12v straight to
the pump on the black/white wire just to see if I can
hear the pump working?

 

[Golden GSX]

small update. I played around some more by holding the mfi relay while turn the ignition on and off and felt it clicking. Still no voltage coming from pin 2 (black/green)

help if you can.

 

[ken inn]

pull your ecu. check for leaky capacitors. if the board smells like bad fish, the electrolyte is leaking out, and probably has eaten thru parts of the circuit board. one of the first circuits to go is power to the mfi. the clicking is because the power is not steady, it is turning itself on and off. not good. if you are lucky, you can get the caps changed, and the board cleaned. if not, start looking for another ecu, and make sure the caps get changed, or this will happen again. lots of people say, "the board looks fine". that is NOT good enough. it is not a question of if, but when.

 

[Golden GSX]

I think you're right. I was only testing the output wire to the fuel pump while turning the ignition to the on position instead of the start. I'm getting about 9-10v while cranking and it goes up to 14v while the car starts until it dies. I'm thinking it's the ECU also. I checked it already, no fishy smell or nothing but they're are some slightly darker areas by those caps. If I hardwired the fuel pump and the car doesn't die, would this prove that it was the ecu?

 

[steve]

I'm getting about 9-10v while cranking and it goes up to 14v while the car starts until it dies. I'm thinking it's the ECU also. I checked it already, no fishy smell or nothing but they're are some slightly darker areas by those caps. If I hardwired the fuel pump and the car doesn't die, would this prove that it was the ecu?

The discolored areas are from the caps leaking. If you ground pin 7 on the MPI relay (ECU pin 56) and the car keeps running then something has happened to the ECU circuit that keeps the fuel pump running. Usually I find one or more circuit traces open from the corrosion caused by the leakage.

Steve

 

[Golden GSX]

Can I drive around with pin 7 grounded or is it just for trouble shooting purposes?

 

[steve]

Troubleshooting only! Your fuel pump will run non-stop.

Steve

 

[Golden GSX]

Car started and I get over 13v at the pump. Car didn't start for a month and now it does.

 

[steve]

So grounding pin 7 makes the car run?

If so time to get your ECU fixed.

Steve

 

[Golden GSX]

well, at first I grounded it turned on the car but it still died. Good thing was I heard the fuel pump working.

So I took the jumper off the pin, got in the driver seat and tried again. While the car was hesitating I was quickly tapping on the gas just a tad and it reved up and went to normal.... besides the check engine light of course.

Threw in the buzzer to the dianostics port and got one long beep, 3 shorts... and 2 longs and 5 shorts...

Looked in the chilton and it says 13 is intake temp and 25 is barometric. So it's my MAS sensor that has been the problem of the car not starting now?

 

[ninety7gst]

i'm having the same problem. except w/ mine i can't even get the fuel pump to turn on w/ the jumper wire wrapped to the firewall... i replaced the fuel pump and still no go

 

[steve]

Looked in the chilton and it says 13 is intake temp and 25 is barometric. So it's my MAS sensor that has been the problem of the car not starting now?

Sounds like it but make sure you haven't lost the either the +5 sensor power or the sensor ground. Reset the ECU to clear any codes just to make sure they aren't saved errors from turning the ECU on with the MAF disconnected. Also check the engine coolant sensor in the thermostat housing to make sure the connectors are good and that it reads good values. A bad one will cause starting problems.

Steve