fuel pump/relay and DTC 44 troublshooting info

[rnj]

This is info is what I used in the last steps of my issue that resolved my symptoms. The following info I received from a friend of mine, on diagnosing a fuel pump/relay problem. He got this from a manual not sure which one.

If you suspect a problem with the fuel pump, verify the pump actually runs. Have an assistant turn the key on-you should hear a brief whining noise as the pump comes on and pressurizes the system. Have the assist start the engine. This time you should hear a constant whirring noise as the fuel pump (but it's more difficult to hear with the engine running).

If the pump does not come on (makes no sound), go to the next step.

Check the fuel pump fuse. If the fuse is blown, replace the fuse and see if the pump works. I the pump still does not work, go to the next step.

Check the fuel pump relay circuit. If the pump does not run, check for an open circuit between the relay and the fuel pump. With the ignition key ON (engine not running), check for battery voltage at the relay connector. The fuel pump relay is located on the fender well on TBI models next to the A/C clutch relay. On MFI models the relay is located in the fuse/relay control box in the engine compartment. NOTE: If the oil pressure drops below the specified pressure level, the oil pressure switch will act as a fuel pressure cut-off device. Be sure to check the oil pressure switch and circuit in the event of difficult problem diagnosing the fuel pump circuit (refer to the wiring diagram).

If battery voltage is exists, replace the relay with a known good relay and retest. If necessary, have the relay checked by a qualified automotive electrical specialist.

If the fuel pump does not activate, check for power to the fuel pump at the tank. Access to the fuel pump is difficult but it is possible to check for battery voltage at the electrical connector near the tank.

Fuel pump relay wiring color code;

orange; hot at all times from fuse #2 15 amp
powers fuel pump relay and fuel pump/oil pressure switch.

gray; sends power to fuel pump from fuel pump relay

black; ground

dark green-white; voltage from the PCM

red; fuel test

fuel pump/oil pressure switch wire color code;

orange; hot at all times from fuse #2 15 amp
sends voltage to fuel pump/oil pressure switch

gray; sends voltage to fuel pump after engine reaches specified oil pressure

When you first turn the key on ENGINE not running, voltage is sent from the PCM using the dark-green/white wire to the fuel pump relay, energizing the fuel pump relay, then voltage is then sent using the gray wire from the fuel pump relay to the fuel pump, pressurizing the system for start only, and the red wire for fuel test. Voltage is only long enough to pressurize the system for start only.

Once the car starts and builds engine oil pressure Voltage is supplied to the fuel pump from the fuel pump/oil pressure switch, using the gray wire.

I think your fuel pump/oil pressure switch is working because, while you a turning the engine over for 30 seconds you are building up enough engine oil pressure to switch power from the engine fuel pump/oil pressure switch to the fuel pump allowing the engine to start. Then during the day if the fuel pressure does not drop, there is enough fuel pressure allowing the engine to start faster.

Check the orange wire at the fuel pump relay for voltage with key off (hot at all times). If there is none, check for a broken wire between fuse #2 and the fuel pump relay mount or a loose connection.

Check to see if voltage is coming from the PCM, at the dark green-white wire. The voltage will last long enough to pressurize the system, then the PCM no long sends voltage. If their is voltage coming from the PCM? Check you connectors at the fuel pump relay mount, shake the wires side to side to see if they make contact if the do you have a loose connector. While pushing on the bad connector from the top (where the relay spades go in), take a small screw driver unlocking the locking tab, under the bottom of the relay mount. Repair the connection (just bent the tabs on the sides of the female spade connectors, do not flatten the female spade connector).Then reset the lock tab and push the connection back in the same way it came out.

If you have no voltage coming from the PCM key on engine off? Check for a bad connection or broken wire, between the fuel pump relay mount and the PCM.

If your connections are good and you have voltage coming out of the relay (gray wire)key on engine off, there is an opening in the wiring between the relay and where the fuel pump/oil pressure switch connection.

A quit way to check the gray wire to the fuel pump/oil pressure switch is, while the engine is running unplug the fuel pump relay and check for voltage at the gray wire because voltage is being back feed from the fuel pump/oil pressure switch(with the engine running only).

If voltage(key on engine off) is coming in at the dark green-white wire and not coming out at the gray and the connections are good. You have a bad fuel pump relay.




This info I found somewhere on the web. This is for a CODE 44 lean condition.

CODE 44
Trouble Code 44 indicates that the O2 sensor is showing a persistently high exhaust oxygen content (lean), despite the efforts of the ECM to increase injector on-time (thus increasing fuel delivered). Integrator and BLM numbers may indicate > 128 by a substantial margin.
Code 44 is set when:
- O2 sensor voltage remains below .2 volt for 60 or more seconds
- System is operating in "Closed Loop."
- No Code 33 or Code 34
Possible causes include:
1) O2 sensor defective or lead shorted
2) Lean injectors (dirty or blocked)
3) Water in fuel
4) Exhaust leaks upstream of O2 sensor
5) Fuel pressure too low
Note: Presence of Code(s) 33 and/or 34 may indicate MAP problem. This should be the first suspect in the case of a Code 44 being set.

[HotZ28]

Originally Posted by mj

This info I found somewhere on the web. This is for a CODE 44 lean condition.

Please give credit to the source, (post a link).

[rnj]

can't find source for code 44, and the fuel pump/relay diags came via an email from a friend, but it was from a manual. b-bodys i'm sure or he wouldn't have sent it. I'll try to track done the code 44 stuff I copy and paste things I need to a doc. and just work off that in the garage.

[rnj]

code 44 diags link


http://www.seanster.com/scantool/ecm-codes.html#44