Fuel pump just quit Options

[surfdogskier]

So I had everything working well on my carb conversion with the exception of the fuel pump which constantly ran unless I pulled the ground wire per SirAndys carb conversion write up.

Now my pump will not work at all. I direct wired it to the battery to see if the pump was good and it worked. I connected a 12 volt wire to my relay board at the black/red wire #13 connection and it worked. So no issue with the wire. However something on the relay board or relay prevents it from working when the key is turned on.

I was going to wire it to the 2 other points on the relay board to get 12 volts (T4b and the #12 pin on the T12 connector). However, with the key turned on, I am not getting 12 volts to either of these. the T4b, I am getting 2 volts and the pin 12 on the T12 I am getting 4 volts.

My only other option to get 12 volt power is to connect to my coil but I have read this is not a good idea.

Looking for some guidance.

[rhodyguy]

the last sentence has me confused. The stand alone(?) wire from the bat connects to what? The pump?

[surfdogskier]

the last sentence has me confused. The stand alone(?) wire from the bat connects to what? The pump?

I ran just an extra wire directly from the positive battery post to my fuel pump wire that connects to pin 13 and my fuel pump works. I used it just to test my fuel pump if it was working. I think that is what my have confused you and I wasn't clear with that.

It is like I am no longer getting power to my relay plate. I'm not getting 12 volts anywhere on it with the key off or on. My fuse on my relay plate is good.

[lierofox]

the last sentence has me confused. The stand alone(?) wire from the bat connects to what? The pump?

I ran just an extra wire directly from the positive battery post to my fuel pump wire that connects to pin 13 and my fuel pump works. I used it just to test my fuel pump if it was working. I think that is what my have confused you and I wasn't clear with that.

It is like I am no longer getting power to my relay plate. I'm not getting 12 volts anywhere on it with the key off or on. My fuse on my relay plate is good.

This is for the 73 relay plate so it might not be completely accurate for your '72, but it's the best I can work off of, if this doesn't apply AT ALL to your application then ignore this!

You should have power going to the Relay Plate from 4 sources:

2 from the battery all the time (Terminals 12 and 14 on the upper connector, red wires)
1 from the key switch when it's in the On position powering the supply side of Fuse 9 on the under-dash relay (Terminal 8 on the upper connector, black wire)
1 from the key switch when starting (Terminal 1 on the connector, yellow wire) but this one can be ignored for right now.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-18880-1572121998.1.png)

In order to get power to the fuel pump working you need the Power Supply relay, the Fuel Pump relay, the 2 battery cables at terminals 12 and 14, the 25 amp fuse, power from the key switch/Fuse 9 at terminal 8, and a chassis ground at terminal 10.

Basically the key switch sends power to the coil of the Power Supply relay.
The power supply relay turns on, and takes the battery power from Terminal 12 and sends that power to the coil of the fuel pump relay.
The fuel pump relay's coil is switched from the negative side at the "Ground To Enable Fuel Pump Relay" which is usually a job done by the ECU when fuel injected.
When all of the above conditions are satisfied, the Fuel Pump relay turns on, and power from Terminal 14 goes through the 25 amp fuse, through the Fuel Pump relay, and back to Terminal 13, and finally to the fuel pump through the Red/Black wire.

This is just the fuel injected operation of the fuel pump, what exactly does the guide tell you to do to change it for carbs?

[surfdogskier]

the last sentence has me confused. The stand alone(?) wire from the bat connects to what? The pump?

I ran just an extra wire directly from the positive battery post to my fuel pump wire that connects to pin 13 and my fuel pump works. I used it just to test my fuel pump if it was working. I think that is what my have confused you and I wasn't clear with that.

It is like I am no longer getting power to my relay plate. I'm not getting 12 volts anywhere on it with the key off or on. My fuse on my relay plate is good.

This is for the 73 relay plate so it might not be completely accurate for your '72, but it's the best I can work off of, if this doesn't apply AT ALL to your application then ignore this!

You should have power going to the Relay Plate from 4 sources:

2 from the battery all the time (Terminals 12 and 14 on the upper connector, red wires)
1 from the key switch when it's in the On position powering the supply side of Fuse 9 on the under-dash relay (Terminal 8 on the upper connector, black wire)
1 from the key switch when starting (Terminal 1 on the connector, yellow wire) but this one can be ignored for right now.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-18880-1572121998.1.png)

In order to get power to the fuel pump working you need the Power Supply relay, the Fuel Pump relay, the 2 battery cables at terminals 12 and 14, the 25 amp fuse, power from the key switch/Fuse 9 at terminal 8, and a chassis ground at terminal 10.

Basically the key switch sends power to the coil of the Power Supply relay.
The power supply relay turns on, and takes the battery power from Terminal 12 and sends that power to the coil of the fuel pump relay.
The fuel pump relay's coil is switched from the negative side at the "Ground To Enable Fuel Pump Relay" which is usually a job done by the ECU when fuel injected.
When all of the above conditions are satisfied, the Fuel Pump relay turns on, and power from Terminal 14 goes through the 25 amp fuse, through the Fuel Pump relay, and back to Terminal 13, and finally to the fuel pump through the Red/Black wire.

This is just the fuel injected operation of the fuel pump, what exactly does the guide tell you to do to change it for carbs?

Thanks for this image and info. I haven't seen one like it that details the relay board and wires so easily. Adding it to files!

[lierofox]

Thanks for this image and info. I haven't seen one like it that details the relay board and wires so easily. Adding it to files!

You're welcome, it's actually an image I found and spent a few hours in Photoshop going through and redoing all the wording for the pin terminals and the relay terminals because the original text was almost completely unreadable.

See also: https://www.youtube.com/watch?v=QEzhxP-pdos