Bee Saint Louis

I had this setup for my Holley with electric choke, Thanks. Now I'm adding an electric fuel pump and this same switch is recommended for that also. How do you accomplish both? (If I need to start a new thread I don't mind. )

joe_padavano

I split your post off into it's own thread because it's a good question and a somewhat involved answer.

First, if your only desire is to power the pump while the engine is running (and has oil pressure), then the easy thing to do is to simply splice into the wire that feeds the choke and use that to operate a relay to turn the pump off and on. This won't effect operation of the choke and will ensure that the pump won't be running when the engine is off.

The downside to this is that you lose one of the advantages of an electric pump, namely that you can use it to prime the carb after the car has been sitting for a long time to avoid a lengthy cranking on first start. GM solved this problem when they designed the Vega. The factory electric pump uses a similar oil pressure switch that has different internal connections. The Standard Motor Products PS64 looks just like the PS127, but note that the three terminals are labeled "P", "S", and "I". The "P" terminal goes to the pump (or the relay if you are using a relay to drive the pump). The "P" terminal is connected to the "S" terminal when there is no oil pressure. "S" is for starter and this terminal should be connected to the "S" terminal on the starter solenoid. In this application, it also provides power to the electric pump as soon as you turn the key to START, allowing the pump to prime the carb before oil pressure comes up. Once oil pressure rises, the "P" terminal is disconnected from the "S" terminal and instead connected to the "I" terminal. (for ignition). This should be wired to a 12V source that is powered with the key in the RUN position. This way the pump is only powered when there is oil pressure. To run both PS127 for the choke and PS64 for the pump, use a brass tee fitting at the oil pressure port. If you also want to run a gauge, use a brass cross fitting. Note that in the wiring diagram below, the "P" terminal is the "C" (common" terminal), the "S" terminal is the "N.C." (normally closed) and the "I" terminal is the "N.O." (normally open).

redoldsman

It is good to know the Vega served some useful purpose.

joe_padavano

Without the Vega, we'd never have the 1970s vintage Olds Starfire.

Bee Saint Louis

Ok Joe. Thanks. I did end up with a Ron Francis electric fuel pump Relay and wiring setup. I still have choke attached and assembled via the ps127 and an oil pressure gauge currently.

I'm stumped on how to incorporate his setup with a safety setup for my fuel pump. Any suggestions with what's done so far.

Also, what's the difference between getting 12v from starter solenoid near headers and straight from battery post with available spot?

matt69olds

joe_padavano

You can simply connect the orange wire from the FP-35 kit to the terminal that feeds the choke from the PS-127 switch. The problem with this is that the fuel pump won't be powered until the engine oil pressure has come up. The advantage to doing it with a separate PS-64 switch is that the fuel pump will be powered directly while you crank the starter (to ensure the carb is primed) and will then revert to being protected by the oil pressure switch once the key is turned to the RUN position. If you choose to go with the PS-64 switch, connect the orange wire from the FP-35 kit to the "C" terminal on the switch.

Bee Saint Louis

I'll go with the orange wire to choke terminal on ps127.
I have headers and a mini torque starter with positive battery cable there and purple wire. Which wire should my red wire be connected to from relay? Currently I think it's incorrectly attached to an open terminal on the battery. Thanks

Bee Saint Louis

Have all wires connected, except one. Just waiting on confirmation about the red wire needing to be connected via the starter battery terminal. If I have to have it connected there, the battery terminal or if I should splice into the purple starter wire before it gets to the starter. Thanks for the help this far.

Bee Saint Louis

Fuel pump works. I can hear it in the back of the car humming. On another note, I have a leak in between the fuel filter and the pressure gauge. I'll address it tomorrow and try to start the car again at that time. Thanks for your help.



* I end up connecting my red wire from relay to battery terminal connector.

Firewalker

The old style method seems to be the best and the most practical to me. A cheap Holley Red or possibly a Carter pump, by the tank, feeding a mechanical pump on the engine. The W30 replacement should fit with little flattening of the rim/lip on the pump, for clearance. Use a switch for the electric for when more flow is anticipated, or when you want the fuel bowls need to be filled fast, with the engine off. This method is quite most of the time, and allows the electric to last a long long time. Decades ago I had a mechanical fail, and the electric saved my bacon and got me home to get another pump and put it on.