|
The Situation:
Over the weekend my 1991 Volvo 240 just died. I had it towed back to the house. I started trouble shooting and found that the fuel pump was not engaging.
Troubleshooting:
All the reading I've done here says start with the Fuel Pump relay. I replaced it. No go. I then put the old relay back on with cover off it. so I could watch it.
Fuel Pump Relay
Ignition OFF:
Pole 30 = steady 12V.
Ignition ON:
First pole (86/1) and (87/1) engaging.
Ignition to START:
Second pole (86/2) and (87/2) DOES NOT ENGAGE.
ECU LH2.4:
Both the ECU and the ECM are pulling codes 1-1-1. So all of the inputs appear to be in working order.
I went through all the tests in the Bentley Manual for the LH2.4 system testing each lead on the unit with a Multimeter. The ECU Passed Every test.
The fuel pump relay test, when I ground ecu lead 20(Bl/Grn) that runs to the relay it engages the first pole on the relay. If I ground both leads 20(Bl/Grn) and 21(Yl/Bk) which go to the relay, both poles engage and the fuel pump runs.
I opened and visually inspected the ECU. There were no burnt leads on board. It visually looked fine.
Conclusion
Lead 21(Yl/Bk) is not supplying the proper ground as it should when the key is turned to the START Position. ECU otherwise is working fine.
Workaround
Since lead 20(Bl/Grn) is supplying the proper ground when the key is turned to ON, I have spliced together 20(Bl/Grn) and 21(Yl/Bk) on the relay side. When the key is turned to ON the fuel pump will begin running. When it is turned off, the fuel pump will run for approx 5 seconds and turn off.
Looking for the correct fix
So, with all the information I've provided does anyone know what the proper fix for this problem is? I feel like I've run out of things to test. I've done everything short of just starting to randomly replace parts.
Also, does anyone know if there is negative ramifications of doing the workaround I've done above?
|
