Oil pressure sender question

[Ponymedic]

Need some help running gauge wiring for oil pressure sender. Leads from Ron Francis harness have Gray and black for oil pressure and ground but sending unit has white black and red. red is labeled 5 V reference not quite sure with that needs to be hooked up to

[edwardb]

This is a recent change, based apparently on the failure rate of their 2-wire resistive style sending unit. I read where they've changed to this 3-wire unit which is supposed to be more reliable. Your gauge package should have included a 3-wire cable for hookup, and the gauge itself should have the 3-wire plug which apparently provides the added 5V reference voltage. Easiest solution in this case is probably to use the Speedhut cable and not the Ron Francis wires.

[Ponymedic]

Thanks not familiar with the speedhut cable which one and where do I get

[edwardb]

Thanks not familiar with the speedhut cable which one and where do I get

Sending units and cables should all be in the box with your gauges. Also the instructions are in there. I'm assuming you have the Speedhut gauges... Like these? http://www.factoryfiveparts.com/16007-factory-five-vintage-gauge-set-w-gps-speedometer/

If not, my answer may not be correct.

[Ponymedic]

Those look like the gauges I was following the ff wiring manual that instructs to cut off leaving a pigtail? Should I have run directly to the gauge?

[edwardb]

Those look like the gauges I was following the ff wiring manual that instructs to cut off leaving a pigtail? Should I have run directly to the gauge?

Probably you don't have a choice since the RF harness (and instructions) aren't updated to the gauge change from Speedhut and doesn't support the 3-wire sending unit. But one hint: There's not one source for wiring the gauges. You need to use the RF wiring instructions, leaning heavily on the schematic, not just the written instructions. Plus the instructions that came with your gauges. While the most recent RF harness is a little more compatible with the Speedhut gauges than previous versions, it's still a universal harness and used in several different kits and different gauge sets. Plus there's going to be some variation depending on what engine and fuel/ignition installation you're doing. It's not necessarily plug and play if that's what you're expecting. You need to understand what's happening with all the various pieces and wire accordingly.

[Ponymedic]

You are correct. I just called the Tech line and they confirm that I should not be following the wire harness instructions. I'm a little unhappy that there was not a notice or bulletin anywhere. I'm taking great pains to minimize splices as much as possible and this one was totally avoidable. They suggested that I may be able to buy a replacement from speedhut directly
But as always thanks for your help
Nick