1984 troubleshooting fuel system
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
I used veteoz diagtams and ohmed out everything. It all checked out but had no pump when I used terminal G or any method to run the pump.
Racer
Joined: Aug 2013
Posts: 301
Likes: 0
That should mean that for whatever reason the relay is not getting a signal to the pump. You can use the diagram that vetteoz posted to check for power, ground, signal input and power output at the relay connector. If those are all good along with the wire to the pump, it could be the relay itself.
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
My 84 would not start. I replaced the OP switch and it would start if I rode the starter. So I put a switch that I press and runs the fuel pump so I can start then I take my finger off and it is running.
I used veteoz diagtams and ohmed out everything. It all checked out but had no pump when I used terminal G or any method to run the pump.
I used veteoz diagtams and ohmed out everything. It all checked out but had no pump when I used terminal G or any method to run the pump.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I don't know if this applies to '84s, but later ECMs require reference pulses from the distributor to tell them to turn on the fuel pump. They also use the reference pulses to synchronize the firing of the injectors to the rotation of the engine.
Check the 4-wire harness coming out of the back of the distributor (it goes to the ECM).
Check the 4-wire harness coming out of the back of the distributor (it goes to the ECM).
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Different years have different configurations of the oil pressure switch/sensor. Some have two separate units (the switch has two wires, the sensor has one). Other years have one unit with a 3-wire connector.
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
thank you
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Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
common for them to go bad
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
The relay is new and I actually made some repairs to the wires. They looked awful. I will try your suggestion. Thank you
Heel & Toe
Joined: Apr 2013
Posts: 24
Likes: 2
take a look at the o2 sensor wire and see if it has been messed with. possibly a resistor or pot was installed inline to make it run rich. also are the injectors the right ones. some people put 454 injectors in there.
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
believe me this guy did not do any upgrades. he rarely if ever changed the oil. So changing injectors is out of the question.
I ohmed all of the wires and they were correct. but I could not get the G terminal or the A to E to run the pump.
I put in a switch that I depress to start the car and it runs fine. But I want to check the Fuel pressure and eventually look at the wiring. As of this moment the wipers are slow to respond, the fuel pump does not come on when I turn the key, the rear defroster does not work, the heat barely comes on and I had to put a switch to run the cooling fan (it blows the fuse as soon as it reaches operating temperature).
Right now if I can assure my self that it is running correctly no surges or hesitation I am a happy camper.
I ohmed all of the wires and they were correct. but I could not get the G terminal or the A to E to run the pump.
I put in a switch that I depress to start the car and it runs fine. But I want to check the Fuel pressure and eventually look at the wiring. As of this moment the wipers are slow to respond, the fuel pump does not come on when I turn the key, the rear defroster does not work, the heat barely comes on and I had to put a switch to run the cooling fan (it blows the fuse as soon as it reaches operating temperature).
Right now if I can assure my self that it is running correctly no surges or hesitation I am a happy camper.
Heel & Toe
Joined: Apr 2013
Posts: 24
Likes: 2
You cant check the fuel pressure unless you splice in a t between the throttle bodies. Its factory set and can be adjusted but requires drilling and a special tool. use a timing light to see a quality spray pattern. also if it hesitates its probably the fuel pump itself. I did the tpi fuel pump and that helped alot. new relays are not always good. most of my wiring nightmares were the overlooking of newly installed relays. so i would suggest to remove the relay and check it. sometime it can be an intermittent relay failure and that can make troubleshooting even worse. case in point, the blower motor relay can cause the heater fan to be slow. so replaced it a few years ago. now last summer stoped working. so replaced selector switch. no good. the newly installed relay stuck and didn't work. quality is just not here anymore. original lasted 27 years. new not so long.
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
You cant check the fuel pressure unless you splice in a t between the throttle bodies. Its factory set and can be adjusted but requires drilling and a special tool. use a timing light to see a quality spray pattern. also if it hesitates its probably the fuel pump itself. I did the tpi fuel pump and that helped alot. new relays are not always good. most of my wiring nightmares were the overlooking of newly installed relays. so i would suggest to remove the relay and check it. sometime it can be an intermittent relay failure and that can make troubleshooting even worse. case in point, the blower motor relay can cause the heater fan to be slow. so replaced it a few years ago. now last summer stoped working. so replaced selector switch. no good. the newly installed relay stuck and didn't work. quality is just not here anymore. original lasted 27 years. new not so long.