I have a twin pump setup with one pump on a Hobbs. I want to see if the second pump is kicking on. I pulled the plug off the hobbs and used a fuse to short across the two pins. That should turn on the second pump. The regulator needle does not even move when I do that--with the car running. Shouldn't the pressure change when the second pump kicks on? 2005 GTO, in tank pumps.

 

If each pump is fused - pull the fuse on the primary and then with the hobbs connection shorted - see if it will start and run on the second pump.

 

Both are on a separate relay, but fused separately. I pulled the primary relay and the second pump is dead. dead. dead. The primary relay looked like it was getting hot. What amp relay do you guys use. This was a 50/30 with no mfg name---maybe chinese. I got a Dorman 30 amp from the parts store Haven't checked if it is getting hot also. The power wires are plenty big.

 

Relays are not designed to protect like a fuse or breaker. Get a 50 amp relay and let the fuse do the job of protection

 

Thanks

 

Not sure what bulk head connector is used on the GTO fuel tank assembly. But dependent on fuel pump size and amp draw, the connector might be a bottleneck if the pins aren't large enough inside the connector that connect to the wires running to each of the pumps. This might be your issue when the second pump fires - brownout.

For example each of the larger pins on the 280/150 bulkhead connector can handle up to 30 amps compared to the smaller pins that max out at about 14 amps. This bulkhead connector for the Fbody from Delphi is an upgrade over the original - but not sure if it is the same as that used on the GTO.

Note the difference in pin size on the yellow bulkhead connector for the 98 Fbody compared to the pin size on the upgraded bulkhead connector for the 1999-2002 fbody. The yellow bulkhead connector can't handle big amp draw pumps (over 14 amps). It can be rewired to run two pumps each at 14 amps. The upgraded bulkhead connector can.

https://www.racetronix.biz/p/connect...80-150/rcs-027

https://www.racetronix.biz/p/fs-bulk...y-4-way/bca-4w

 

Thats good info! I have to empty the tank and pull the pumps so I will be able to check it. The fuel pump module is aftermarket Proxses unit with a complete wiring harness. I know the wires to the pump assembly are large enough, no sure about the plugs. I have two pumps on order so I will find out soon.

 

why would the secondary pump burn up if you only run it under boost? Thats the question you should be asking.......or better yet trying to figure out. My guess it even tho you THINK the wiring is up to snuff, it really might not be. I have a high quality silicon jacketed 10ga wire running to my secondary pump. Or maybe you just have a cheap pump like a walbro knockoff? I'm not going to bash any name brand pumps, but all are not created equally reliable. I choose aeromotive over anything else.

 

On the Proxese site I couldn't find a dual pump kit. I only found a single pump kit for the GTO.

If you converted the single pump kit to dual pumps and didn't rewire the plug that connects your external wires to the internal wires to each pump that might explain why the pump failed (burned up).

Thing is do you really know why the pump failed? Perhaps just a bad pump. I had a 340 lph pump that failed in less than 8 hours - it happens.

But assuming the pump did fail (burn up). IMO, to run big pumps that draw a lot of amps, you need to run a dual wire harness with relays to each pump. The wire size to the alternator must be a minimum of high quality high strand count 10 gauge wire. One wire and ground harness and relay for each pump.

If you look at the Racetronix dual wire harness for dual pumps you will see that each internal pump wire connects to a single terminal in the plug (called a bulkhead connector - see pic in previous link) on the fuel assembly hat. Assuming your plug has four terminals - the positive hot wire from each pump connects to a single terminal on the plug and the other two perhaps for the fuel sender. On the fbody bulkhead connector the two largest terminals each handle up to 30 amps.

Just speculation: but it's possible your single pump attaches to the bulkhead connector plug with one hot wire to one terminal and the other ground wire to another terminal on the fuel side of the connector. If you didn't change the wire configuration when you added another pump, then you are running two big amp draw pumps from a single terminal. If the terminal in the plug can only handle up to 20 amps then one or the other might fail.

Again - just speculating. You will have to examine you wire configuration to see how both pumps connect to the plug on the hat of the fuel pump assembly on the fuel side.

If it is wired at explained above, then you need to rewire so each positive wire from each pump connects each to a single terminal (obviously the largest pins if they are different sizes) on the fuel side of the connector. On the atmosphere side of the plug you will have to rewire the harness to account for the second terminal as a positive plugin rather than negative.

So what to do with each ground wire from each pump? You will have to add a ground plug on the fuel assembly hat and attach each ground wire from each pump to it. And then attach the ground to your reconfigured external wire harness on the atmosphere side.

Pic in link is atmosphere side on my 98 showing the grounding post and how the ground wires run into the short wire harness that connects to the stock bulkhead connector that gets power from the ignition while at the same time links to two single harness's running directly to the alternator.




Note the little yellow plug with the small terminals shown in a previous post in this thread. Racetronix changed the external harness and inside wires exactly as explained above in order to upgrade a single 1998 stock pump to dual pumps using the smaller sized pins on the yellow bulkhead connector. Note that the max amp draw for those size pins in the plug is 14 amps per pin. The yellow plug isn't going to handle two 450 lph pumps or more. It might handle two 340 lph pumps.

Dual wire harness with dual relays.



I noticed that Proxes specifically states that the wire harness on the external atmosphere side has to be sufficient to handle the amp draw of the single pump in their kit.

 

Proxses has gone to a single 400 for the GTO. My setup is older and is a twin pump setup with a new wiring harness with the -10 power wires for both pumps and relay for both.. DW300/340. I don't know what happened to the secondary pump, but it is dead. The new pumps are installed and working. Thanks for all of the info!!