SPF Fuel pump wiring

[Mike Christian]

I have a mechanical pump on my car, and I want to use the switched fuel pump wiring in the loom to power something else located at teh abck of the car. I am looking at the SPF supplied info and looking for a loom breakout with some unused wire - no joy. I have an early LH Drive MKII. Can anyone help me locate the fuel pump wires?

Thanks,
Mike

 

[Jack Houpe]

Mike it will be the #12 size Black and Purple wires. They are controlled by the switch on the dash that controls 2 relays, one for each wire. Also the wire loom that has computer control for fuel injection has a GROUND only wire which will activate the relays.

 

[Lynn Miner]

Mike

Jack is correct but be advised that there is a wiring problem on the early SPF cars in that the fuses for the pumps are wired through the fuses for the AC fans. There is a recommended fix called <style type="text/css"> <!-- @page { margin: 0.79in } P { margin-bottom: 0.08in } --> </style>GT40 Service Bulletin: 0702GTB HVAC Blower Fan Relay Retrofit. I have a copy of this Service Bulletin so email me if you want it. Depending on the amount of current you will be drawing from the pump circuit, you may not need the mod.

The problem surfaces when you have the AC running full tilt and there is a heavy load on the pump circuit.

 

[Lynn Miner]

Mike

I forgot to elucidate that the black and purple wires are shrink tubed together (just those two) and run along the left side by the seat into the engine compartment. They are both + 12VDC. You can use either one or both to drive two different circuits (but they'll be switched together). You can use any ground. Simply connect your multi meter to either wire, any ground point and hit the switch. You'll get 12 VDC.

 

[Jack Houpe]

Mike

Jack is correct but be advised that there is a wiring problem on the early SPF cars in that the fuses for the pumps are wired through the fuses for the AC fans. There is a recommended fix called <STYLE type=text/css> <!-- @page { margin: 0.79in } P { margin-bottom: 0.08in } --> </STYLE>GT40 Service Bulletin: 0702GTB HVAC Blower Fan Relay Retrofit. I have a copy of this Service Bulletin so email me if you want it. Depending on the amount of current you will be drawing from the pump circuit, you may not need the mod.

The problem surfaces when you have the AC running full tilt and there is a heavy load on the pump circuit.

Wow Lynn didn't know about this. Your car is an early car did you have this problem?

 

[Lynn Miner]

Yes, Jack my car had this problem. In fact, I was the first to discover it. I worked with Mike Evangelo of Dynamic to figure out what the problem was. He then worked with Hi Tech to design a fix. I installed the first retrofit and it worked great. Very few dealers, or owners ever heard of this issue and its fix. It's only a problem when there is a significant load on the pumps when the AC is full tilt. My car uses three fuel pumps so it stressed the system a bit. If the load is not that great, you will likely never see a problem. However, the idea of wiring the pumps through the AC circuit is not too smart whether it creates a problem or not and everyone should install this mod. When the system fails, you will be stuck by the side of the road with not apparent reason why the fuel pumps don't work unless you notice that the AC fuse is blown.

 

[Jack Houpe]

Yes, Jack my car had this problem. In fact, I was the first to discover it. I worked with Mike Evangelo of Dynamic to figure out what the problem was. He then worked with Hi Tech to design a fix. I installed the first retrofit and it worked great. Very few dealers, or owners ever heard of this issue and its fix. It's only a problem when there is a significant load on the pumps when the AC is full tilt. My car uses three fuel pumps so it stressed the system a bit. If the load is not that great, you will likely never see a problem. However, the idea of wiring the pumps through the AC circuit is not too smart whether it creates a problem or not and everyone should install this mod. When the system fails, you will be stuck by the side of the road with not apparent reason why the fuel pumps don't work unless you notice that the AC fuse is blown.

Being a electronic tech and having built my car and helped with a couple more I have found more than one issue that in my mind is poor engineering electrical wise. I have made some retrofits myself and for my friends with great success. The blower motors circuit is one and an important issue. I am sorry for thread drift. If anyone is interested I will start another thread. Thanks for your information, your information on your build has helped me a great deal.

 

[Mike Christian]

Thanks Gents! I am using it for the backup camera so I probably won't need the relay mod. I was trying to find the wires and the diagram in the manual says it breaks out of the RHS and goes left after the brake switch. Lynn, I see a small bundle coming through the bulkhead on the LHS - this might be it. I have to follow it to see where it goes.

Thanks again!

Mike

 

[Mike Christian]

The blower motors circuit is one and an important issue. I am sorry for thread drift. If anyone is interested I will start another thread. Thanks for your information, your information on your build has helped me a great deal.

Please do Jack! I am interested in this as well...

 

[John]

Yes Jack, that would be greatly appreciated.

Thanks,
John

 

[Mike Christian]

I found the wiring in the small cubby hole behind the driver's seat. Posting about my camera install in my original GT40 ownership thread in the Superformance forum.