Jumper to avoid being stranded with a failed Primary Fuel Pump

[QB93Z]

After the fourth time that a failed primary fuel pump "stranded" a ZR-1 (mine once and three friends' ZR-1's). I decided to make an extension cable that swaps which fuel pump acts as pump # 1.

Background: If number 1 fuel pump fails, the LT5 will start properly but then die after a short period of time. When the engine is cold, the period may be almost a minute. When the engine is at operating temperature the engine will die immediately after starting.

This happens because the ECM energizes BOTH fuel pumps on engine start. So the Secondary Fuel Pump supplies fuel to the injectors while the primary pump does nothing. Once the engine is operating properly, the ECM turns off the Secondary Fuel Pump and the car stalls.

Here is my solution:



This jumper switches the wires in the plug to make the Secondary Fuel Pump get power from the Primary Fuel Pump's source. The jumper is pretty easy to install:

1. Pull back the rubber boot around the gas filler neck to access the wiring harness that is clipped to the rear facia:



2. Remove the small gray lock pin from the connector clip:



3. Separate the male and female halves of the connector:



4. Then connect the ends of the jumper into the circuit to the pumps.

5. Start the car to test the connections. As soon as possible, replace the failed primary fuel pump and remove the jumper.

6. I recommend that if you use the jumper to swap a failed primary fuel pump, you should turn the Power Key OFF (Normal). Without the second fuel pump operating, if the secondaries opened, there might be a problem with a lean condition due to insufficient fuel supply.

Based on the rules of Murphy's Law and Good Mojo, when I carry this jumper, I will never need it, just like the alternator that I have carried for about 30,000 miles of road trips that I haven't needed to use.

Enjoy the Road,

Jim

[Demps]

Genius!

Part numbers and source(s)...sorry if I missed them.

Ted

[Dynomite]

Just so I understand this Jim......

The jumper you made up can be much shorter as it is only used to just switch wiring within the connector?

Exactly which wires are switched?
We have green, white, red, black wires from bottom to top on each side of the connector.
Green (on right) now goes (in your jumper connector) to what color (on left) and so on? I assume only two wires are switched....which two wires?



Great concept/solution Jim
Thanks

Oh....Jim I do carry tools and a volt meter (drivers side box), Jumper Cables and Nylon Tow cable (passenger Side Box) behind seat. I also carry a Tow Bar Adapter located between passenger seat and door sill with Lug Nut Wrench.

I have never carried a spare alternator

[Kevin]

I need one of these

[RussMcB]

Clever. Thanks for sharing.

[PhillipsLT5]

Originally Posted by Kevin

I need one of these

Me too

[Hib Halverson]

Why not jump the secondary fuel pump test connection to the battery?

Isn't that easier?

[QB93Z]

Originally Posted by Hib Halverson

Why not jump the secondary fuel pump test connection to the battery?

Isn't that easier?

The Fuel Pump Test Connection in the wire bundle near the ECM cannot power the fuel pumps when the ignition is ON.

The fuel pump test connection is very useful when 12 Vdc is applied with an ammeter. A running fuel pump will draw about (I don't remember the exact number) 4 amps. If the ammeter reading is > 8 amps, then two pumps are running in test mode.

Jim

[QB93Z]

Originally Posted by Dynomite

Just so I understand this Jim......

The jumper you made up can be much shorter as it is only used to just switch wiring within the connector?

Exactly which wires are switched?
We have green, white, red, black wires from bottom to top on each side of the connector.
Green (on right) now goes (in your jumper connector) to what color (on left) and so on? I assume only two wires are switched....which two?

There are four wires in the connector:

Black - DC ground
Purple - Fuel level sensor signal to the fuel gauge display
Gray - 12 vdc to a fuel pump
Lt Green (or Green/White) - 12 vdc to the other fuel pump

My short jumper is just a cross-over jumper, as Cliff said. By switching (crossing) the gray and green wires, the 12 vdc from the Primary Fuel Pump is routed to the Secondary Fuel Pump.

The part number for the connector on the harness (car side) is:

Connector, elec, Fuel Pump, Male GM 12085534 (AC Delco PT145)

Here is the part on Amazon:
http://www.amazon.com/ACDelco-PT145-.../dp/B000C9SNX0

I haven't verified by ordering the connector for the pump side of the connection. I got the connector I used from a take-out fuel pump assembly from WAZOO donated parts. I THINK (but haven't verified) that GM 88861069 is the female connector, but I can't find a source with a picture.

Jim

[RussMcB]

I did something similar, but not as nice. I just cut the two FP wires and inserted crimp-on bullet male/female connections, so it's pretty easy to unplug them and reattach them Gray to Green and Green to Gray.