Carter P4070 Electric Fuel pump shuts off?

I've installed a carter P4070 electric fuel pump on my 1969 Plymouth road runner. It is mounted at the gas tank and runs through a Holley Fuel regulator, (which has a return line) and runs to my Carter High pro. mechanical fuel pump then to the carb, which is a AVS2 650 Edlebrock. The problem is the electric pump shuts off once the car is running, I don't know what is causing this, I have the electric pump wired using an oil pressure safety switch and I have good oil pressure. This is the 2nd Carter P4070 I have installed as well as the 2nd fuel pressure regulator, there has been no change, the electric fuel pump shuts off at some point after the car is running, am I missing something obvious? Thanks, 6T9RR

Depending on how it's wired maybe the problem. The oil pressure switch may not be able to handle the current the pump requires. This would result in a voltage drop to the pump and potential damage of the motor or the switch contacts. More info needed

I was going to suggest bypassing the cutoff switch and see if it still happens.

The oil pressure switch shouldn't be carrying the electrical load because I have the pump wired through a relay. At least that is what I thought the relay is for, to carry the load once it is switch on, the oil pressure switch will turn the relay off if oil pressure is dropped off below 5 - 3 psi. I do appreciate the input thought.

My thought was more on the line of a defective switch.

might be overheating the pump and tripping a thermal cutout. You really need to get in there with a meter when it's happening and see what's missing.

Providing the relay is wired properly, the connections are all good,The relay and wiring are sized properly about the only thing left is a flaky ground. Doubtful you would get two bad pumps in a row but possible.
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A schematic would help

Have you tried a failed pump off the car??? Maybe check the resistance across the terminals?? Next stop might be to call their tech support.

I've double checked the wiring itself, all things look good, gauge, connections, grounds, as for the oil safety switch, I'll have to look into checking to see if it is operating correctly. I have read about thermal shut downs on these pumps happening, I'll have to work on wiring up a multi-meter to see if I can detect when it is shutting down, then checking the pump to see if it is hot. Again, I do appreciate all inputs, this has been an issue since I put the first P4070 in last September.

This may have already been covered but I would run 12V right to the pump itself & take it for a spin, if (now) ok this would elim the pump/ground path.

hi
hi you must have the right psi switch , it will need to be a n o switch . < normaly open > psi will close the contacts to run te pump.

It runs for a while then shuts down.

The switch isn't magically changing from NO to NC.

However, if the Oil pressure switch is not and on / off type switch, but rather one that varies the resistance to ground via the oil pressure being being produced ( think gauge sending unit), it could cause some issues activating the relay coil keeping in mind the resistance changes as the engine warms up and the pressure drops.

Roberts idea is also not a bad one as it would identify the circuitry or the pump as the culprit

keep us posted

Well switch does imply on/off and sender implies variable resistance. So assuming he does have a switch like he stated then that should not be it. But if he had a sending unit instead then yeah that might be an issue but he'd have to have something like a temperature sender that changes as it gets hot. Oil pressure sender would pretty much change immediately once the engine is running.

This is part of the difficulty we encounter when trying to help troubleshoot something online. We don't always know exactly what has or hasn't been done on the other end.

With more thought I dont think it is the pump/ground but I still think I'd grab a long jumper & get those parts elimed.

Hi All,
This is what I learned today trying to test the electric fuel pump. I turned the ignition on and let the electric fuel pump run without the engine running for about 20 minutes. I wanted to see if the pump would fail on it's own for no apparent reason or if it would stop if it got to hot. It did neither. It ran the whole 20 minutes, it did get warm and even a bit hot but not so hot that I couldn't put my hand on it. Next I took the car out for a spin around the block/country roads, when the electric fuel pump shut off I pulled over quickly and put my hand on the pump, it was cool to the touch. I turned the car back on, it fired back up, and the electric fuel pump was running fine. I now think it is the oil pressure safety switch as one of you told me before. I need to eliminate it from the circuit and try it again. I'll update this post once I figure out how to do that. Thanks for all the advice, I really appreciate it!

Nice, keep us informed please.

4/9/2018 Update: I put a meter on the power line from the relay to the fuel pump and when the ignition switch is "on" the power line shows 12 volts and the fuel pump is running. Once I start the motor the power line goes to "0" and the pump shuts down. I have already replaced all the components, the pump, relay, oil pressure safety switch, the wiring has been triple checked. I will now research how to test a holley 12-810 oil pressure safety switch to see if they are in fact bad. Thanks, Paul 6T9RR

Chevy had a three terminal oil pressure safety switch on the vegas. You might want to check that out as it would kill the fuel pump when the oil pressure went away but the minute you got oil pressure it powered the fuel pump.

Diplomats used a similar switch to power the choke only when the engine was running. Since his FP is on a relay that switch would also work fine for his setup.

Looking at the wiring diagram for the switch on holleys site I am going to guess you have a mis wire. Reason being,

1. you say the pump runs with the key on but stops when the motor is running.

Per their diagram the switch terminal N (normally closed contact) should be wired to the starter relay (start terminal). This puts power to the pump while the engine is being started

Terminal NO (normally open contact) should be wired to the input side of the ballast resistor or to a terminal that is hot in the run position. This puts power to the pump once the engine starts and builds oil pressure

Terminal C is the common and hooked to the pump.

HOLLEY SWITCH INSTRUCTIONS

Depending on how your relay is wired it may also be the problem. (HINT) It may be interesting to note per their digram and instructions, they do not require a relay. (HINT x 2)

A schematic or or drawing of your wiring would help tremendously. keep us posted

I’m not really sure how much of a failsafe the oil switch can be in this particular situation.

The electric pump is feeding a mechanical pump....... so even without oil pressure, and the electric pump turned off...... the motor still runs.

Just eliminate one more item that can cause problems...... the oil pressure switch.

I would just run it off a switched 12v source like most everyone else does.. unless of course there's some mandate for you to connect it through the oil pressure switch. I run the p4070s on a car with a direct 12v, and on a truck just wired into an under hood switched 12v source. Those are very low amp draw pumps and don't even need a relay.

that mandate would be called safety. With a switched 12V the pump will continue to run in an accident potentially pumping gas into a fire. By using the oil pressure switch the pump will not run without the engine running. In the case of an accident that doesn't stop the engine the pump will feed the engine and it will run without pump gas out in the the environment. If it does pump it out into the environment then the engine stops running, no oil pressure, pump shuts off.

But go ahead and do it your way.

Agreed and will mention: say the engine loses oil pressure while running, the switch shuts the pump off, the mechanical ( as already mentioned) will continue to pump and even if the mechanical was not there by the time the fuel bowls are drained the engine most likely will have suffered bearing damage at a minumum.

You don't use the oil pressure switch to save the engine bearings.

It's there so that the electric fuel pump will not continue to pump gasoline if the engine shuts off. Such as in an accident.

If you need something to monitor your oil pressure in order to save your bearings use a gauge or an IDIOT light in parallel.

Okay, I finally figured it out. TJP is correct, I had the NO wired to the NC input and the NC wired to the NO input on the oil pressure switch. I got confused because of the wiring diagram I used to include the relay, which was not from Holley, so my bad. In any event, I really appreciate everyone's input, it helped tremendously. My car is running stronger than it every has, now that I have good fuel pressure at high RPM. I laid down a 1st and 2nd gear burn off this morning that would've have made everyone here very proud!

Thanks again, I really appreciate all the advice! 6T9RR

Damn!