Fuel pump shuts off

[rallyvr4]

I bought this vr4 about a month ago,its been doing this randomly, but now i can't get it started for about 2 days. /ubbthreads/images/graemlins/banghead.gif So fare what I have come up with is the mfi relay clicks back off after about 5 seconds of running. Using a Manuel I have determined that pin 7 on the mfi relay is suppose to get grounded once you turn the key to start but it is not. It keeps getting voltage, if I hard wire ground it our hold the relay down it will stay running. I can not figure out why it is not being grounded. Also I just got the ecu back from ecm tuning, and it's suppose to be all fix. any help would be greatly appreciated.

 

[rallyvr4]

Problem solved

 

[G]

What was it?

 

[rallyvr4]

I thought I had it figured out but it did it again, I thought the safc2 that was wired in by the previous owner was causing it but I fix the harness and it's still doing it, I'm getting despite

 

[Fiascoxl]

Have you double checked the under hood grounds as well as the ecu grounds?

 

[rallyvr4]

Yes

 

[Coltsfan]

Pin seven is power, not ground! Pin six is wired directly to ground point #3 and pin seven gets POWER from the starter relay when you crank the engine. After that, pin 108 from the ECU takes over supplying the 12 volts to pin seven of the MPI relay.

Pin six is always grounded, so whenever pin seven sees power, it will close the circuit between pin #4 (power from sub fusible link #8), and pin #1 (fuel pump +12V supply & fuel pump check connector), allowing power to flow from fusible link #8, through pin#4 across the relay out pin #1 and to the fuel pump.

So what you should see is positive voltage to pin seven from the starter relay during cranking. After that, pin 108 from the ECU will provide power to pin seven of the MPI relay. In the event that the ECU fails to see the signal from the camshaft angle sensor, the ECU should shut down after about five seconds, and stop providing power to pin 7 of the MPI relay. The fuel pump should stop at this point.

 

[rallyvr4]

Why would the car continue to run when I ground pin 7 on the mpi relay

 

[rallyvr4]

I'm getting code 42 fuel pump also.

 

[Coltsfan]

Quoting rallyvr4:
Why would the car continue to run when I ground pin 7 on the mpi relay



Perhaps a failed fuel pump rewire. Or perhaps you have mis-identified pin #7.

click
Page 270 has some good info.

 

[rallyvr4]

Yeah I have the service manual in paper form.

 

[Coltsfan]

Holy smokes, I had a typo in my previous post! I went back and edited it where you see the grammatically incorrect capitol letters.Hope it didn't cause confusion.

Anyhoo, If you have the FSM I assume you concur with my statement?

And nevermind the part about pin 108, because the FSM is different than it was last time I looked at it. Pin #8 from the ECU now triggers the pump section of the MPI relay, and it does so by providing ground to the MPI pin #5. Power then comes in pin #7 from the ignition switch, and exits pin #1 on it's way to the pump.

Hopefully this image will keep the lines from moving around on the page LOL.


Here's the continuation of the BW wire from pin #7 where it comes from IG1 (ignition 1)...

 

[rallyvr4]

That diagram is for a sohc 16valve

 

[rallyvr4]

Problem solved it was the ecu like I thought, it was an intermittent problem so the first time I sent it to ecm tuning it was working, when I sent it this week they said diode number 1 was bad.

 

[iceman69510]

Interesting. They made a repair on mine, and it experienced the same symptom again about a month later. Did they charge you for the second review/repair?