Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
You can jump from terminal "A" to terminal "E" to power the fuel pump. You will want to use a fused jummper to do so, (recommended)
You will want to be sure that there is power at the relay terminal "A" at all times. There are no terminals that would need to be grounded when bypassing the relay. The ECM will ground the "D" terminal to close the contacts in the relay to power the pump for 2 seconds when the key is turned on, after that the oil pressure switch will provide the power. Here is a diagram that may help you.
I noticed the diagram show a fuel pump test terminal. Behind the shock tower, sticking out from a bundle of wires, was a single red wire with a simple female terminal end. Assuming this was the test terminal, I applied battery voltage and heard a single, sharp click from the vacinity of the tank, then nothing more. I could not reproduce the click.
This probably means the pump is bad, correct?
Fred
I suppose I have to drop the tank to unplug the pump?
Master technician
29 yrs. exp., ASE master, cert. in G.M. electrical, a/c, susspension, brakes, electronic steering
OK, thanks for your help. I may need to get back to you on this problem as I get further into it. I have accepted your answers. Nice work, you are quite knowledgable.
Some History. Two months ago, the engine became reluctant to fire on occasion but ran pretty well once started. My first guess, and the easiest to fix was the fuel filter, which I replaced. No further problems
Couple of weeks ago, the check engine light came on and the oil pressure guage started jumping around,from the center of the guage, to pegged on top, to 20. The leads to the sensor seemed solid so I bought a sensor and the special socket to remove it. But the old sensor is an eigth of an inch larger than the replacement and I had to special order a socket. (still don't have it.) I left the connector disconected from the sensor. I did not occur to me that it was part of the fuel pump control system. The car continued to run fine for a week, then stopped dead. After getting the wiring diagram, I suspect the relay was cycling continuously until it failed. Without the connection to the oil pressure sensor, the fuel pump shut down.
I could not get parts over the week end. I opened the wire looms looking for a fuse and tracked the tan/white wire to the firewall connector. With a jumper between A and E, this wire has power to the firewall. I also located and disconnected the 3-wire connector at the fuel tank. I was not able to read power there from any of the three pins.
My next step will be to run power and ground directly from the battery to the fuel pump to make sure whether it is good or bad. I also need to determine why I can't find power at the tank connector. Perhaps there is a fuse in the body wires?
Please send me the electrical schematic from the fire wall to the tank, and especially the wire colors at the tank.
This problem is much more extensive than I anticipaged when I selected a payment amount. I will correct that when we are done, either a tip or another question.
Also, while the car is in my shop, I need to remove the driver's door to repair sheet metal damage or replace the door. I don't see any connector for the wires going to the door. Is there one, or do you just cut and splice.
Thanks,
Sure thing...I think you are on the right track with the oil pressure sensor. However, when you first turn the key on, there should be power to the fuel pump for 2 seconds. (tan and white wire) Here is a diagram of the fuel pump controls.
I am still deep (deeper) in this problem. I want to discuss it further with you. Will you please reply so I can get this project moving forward. I am more than willing to pay additional as this has gotten pretty involved.
I would prefer not to work with another mechanic.
One thing I do need is a diagram ot the ignition switch wiring.
Oh yeah....I kept getting messages on the other post but was locked out for some reason.
Let me give you the diagram for the ignition switch.
It's good to hear back from you. I am not getting a switching signal to the starter when the ingnition switch is tturned to Start. Also no fuel pump relay signal.
I changed the oil pressure sensor and the fuel pump relay. I have pulled the starter to verify its correct operation and get access to the electrical connections.
I have checked continuity through the fusable links at the starter except for one of the two, which I cannot get at, which go the the alternator.
I found and checked the fuse in the small plastic box mounted on the power junction block on the relay bracket.
I think I verified continuity through the tranny selector, of the yellow and purple wires. I get no signal on the yellow wire when the ignition switch is activated.
With key on, and to start, the guages react, the chimes chime, and the Cruise Control actuator on the left fender clicks.
Wanna buy a cheap 90 corsica?
What to do next, I am thrashing.
I will find a way to get you some more $
Don't worry bout the money right now, gotta get er going.
It sounds like you did most of the testing. You will want to see how the ignition switch looks, (or even tests) sometimes the connectors get a little burnt on them. It is about half way down the steering column. the yellow wire that goes to the SNS sometimes will start to turn brown. Or the switch could be bad.
If I remember right, the 90 Corsica didn't have the Passkey2 security system, (which would also be able to shut down the fuel pump as well as the starter)
Behind I/P, RH Side Of Steering Column
The Passkey idea is really interesting because the symptoms could represent that situation. How can I tell. The ignition key is rubber coated but otherwise looks like any old key.
Because the car has a tilt wheel, I can't remove it to get at the switch. Supposedly has to go to a deal to r & r the steering wheel. But I should be able to trouble shoot it at the connector you mentioned. Checking it out next.
I am also helping my son put a clutch in his Dodge D-50 PU so I can't stay on the corsica very consistently.
I'll give you a progress report as soon as I can.
Thanks for the diagram.
I'm pretty sure that the Passkey ones had the diode in the key back in the early 90's. If so there is a way to bypass that, if it is the ignition lock cylinder with a passkey sensor problem. Just see how the switch on the column looks and we can go from there.
Good idea to get the son working on his truck too. I have 4 of them, (sons not trucks, lol) and they don't want to even learn how to check their oil. hahaha
Can I send you a photo? How?
I need a color coded wiring diagram of the switch and related wires. I am going to have to check the switch functions from the connector or wires cause I cant see the switch without removing the steering wheel, and a dealer has to do that.
I know some people send me pictures , not sure how though. One had sent me to a web site to see it. If you can copy it to a printing type of file, then go to mediafire.com, I can download it there, as a PDF file.
The switch I'm showing is on the column about half way down. It should look like this?