No start no spark and no fuel

[shadetree]

Okay its a 90 l plus ran fine just shut off on short trip searched all could think of and tried all the same testing i have found if i supply power to the green yellow strip wire at the fuel pump it starts and runs fine, remove power and dies instantly . I have replaced distributer complete , vaf and main power relay with good used parts also checking i have found fuel relay only clicks under start mod with the ig key and pushing the vaf door open will not start the pump also if i supply power to the fuel relay on the green yellow strip wire it will also start the pump running as well and on the fuel relay there is dim test light power from the yellow black wire no other power to this relay but it will click when you try starting but not send power to pump confused yet well me to any help would be great

[JohnGunn]

I'll try to describe what I get from your description.

When you turn the ignition key to start, the starter solenoid activates the starter and the fuel pump relay clicks and the engine fires and starts to run. But as soon as you release the key and it returns to the on position the engine stops.

If the above is correct the problem seems to be related to power supplied to the relay when the power from the ignition switch in start position is removed. By the way, it is to be expected that power applied to the green/yellow wire at the fuel pump and the green/yellow wire at the relay would have the same effect. They are the same wire. That wire connects the output side of the relay to the fuel pump input.

There are two wires that bring 12V to the relay. Black/red from the ignition switch in start position and yellow/black from the ignition switch in on position.

Here is the path of 12V to that yellow/black wire at the relay.
1. Black/white wire from the ignition switch in on position.
2. Black/white wire into the "engine" fuse.
3. Black/white wire from "engine" fuse to the main relay.
4. This will trigger the main relay to close.

Now tracing the circuit from the battery through the main relay to the fuel relay.
1. Battery to EGI fusible link.
2. White/black wire from EGI fusible link to the main relay.
3. Yellow/black wire from main relay to the fuel relay.

There are two coils inside the fuel pump relay that both activate the switch to send 12V to the pump. Here are the apparent wire pairs for those two coils.
1. Black/red power input to starting coil.
2. Black output to ground of the starting coil.
3. Yellow/black power input to VAF meter coil.
4. Green/red output to fuel pump switch in VAF.

The fact that the car starts and runs when you apply power to the fuel pump means that all the fuses mentioned above are good and that you should have 12V at the yellow/black wire into the fuel pump relay.

If you have power on that wire. The closing of the fuel pump switch is made when the vane in the VAF meter is opened by air being drawn into the running engine.

From the circuit diagram, it looks as if you should have 12V on the yellow/black wire whenever the ignition switch is on, so, if you open the vane of the VAF meter, you should hear the click of the switch to the fuel pump closing. Not hearing that would indicate a problem inside the relay or a problem with the switch inside the VAF, but we know that switch is OK since the engine runs with power jumpered directly to the fuel pump.

All this points to a bad relay. Except the part about getting a weak 12V on your test light. There appear to be two connectors between the main relay and the fuel pump relay.
1. A four terminal connector that the wires from the main relay connect to.
2. A 10 terminal connector in that same approximate location.

It might be a good idea to take them apart and clean them, though the one from the main relay you have checked when you installed the replacement.

With a volt/ohm meter you could check the coils in the relay by comparing the resistance of both coils. I would think they should be about the same.

The pairs of wires would be:
1. Coil activated when starting the car: Input black/red, Output black.
2. Coil activated by the VAF fuel pump switch: Input yellow/black, Output green/red.

I hope this was helpful. The fact that it runs with the fuel pump jumped tells me that the problem is internal to the fuel pump relay. The crankshaft position sensor and the injectors get their power from the yellow/black wire, so it must have power since the engine runs.

I would normally go back and clean up what I have written, but in this case I won't, thinking in my analytical observations you may see something that I have missed.

John Gunn
Coronado, CA

[shadetree]

john thanks it was really a long day yesterday and went through it very fast and not so clear on the problem but you managed to get through it . the only problem we missed is that it does not run with key on it only sends power to the fuel relay with the black red strip wire with key on thats it . the only way to get it to run is supply the fuel pump power but from what you said i think i can get this thing going at least i got a good start anyway thanks for the detail well explained will keep informed im not going to let this go not letting all no how we fixed it thanks again

[shadetree]

thanks john ten pin connector after main relay has three broken pins and is corroded bad cleaning up mess and replacing it tonight looked good from outside but when unplugged wow anyway hats off to ya on the wiring thanks again all has been printed and saved in with manuel here there will be a next time lol

[shadetree]

okay car is running and all is good thanks again for the info john is nice to be able to help a buddy out even thou the fix was on someone elses plate thanks john

[JohnGunn]

Congratulations.

It is a pleasure to be of service to someone with such a positive attitude. There is a lesson for us all in that.

John Gunn
Coronado, CA