Electric fuel pump wiring

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In my cars case (not a race car) the fuel pump is on a relay that energizes when the ignition switch is turned to the run position.
If I want the ignition on or to crank the motor without the fuel pump running I just unplug the relay on the inner fender.
Turn the ignition on to fill the carb bowls and a second or two later turn it to start.
Turn the key off and it kills the ignition and fuel both.

For a daily driver this way made sense to me, and I'm not into throwing multiple switches to start or shut off the car.
Yes Sir. It's a pretty simple concept. That's my very point for this thread. Why would you do it any other way. Ignition and fuel go hand and hand. Don't need one without the other.
 
Yes Sir. It's a pretty simple concept. That's my very point for this thread. Why would you do it any other way. Ignition and fuel go hand and hand. Don't need one without the other.

Some people just love the space shuttle pre launch type checklist I guess.:D
 
Lol !! Sir you do not have to turn the motor over to fill up the carburetor bowels with an electric fuel pump . Turn your fuel pump on. Wait 10 to 15 seconds if that long . Then turn start your engine. Now a mechanical pump you would have to turn the engine over and over and over to feel the bowels up. But there is no electricity on mechamical pump. That's why its called mechanical !! And if your magneto goes out you don't have to worry about killing the fuel. Motor will not be running..

What? you misunderstood my whole post. If your bowls are dry and you have an electric pump (Been there like every morning with a TQ on a 340) and they are on the same circuit as your ignition, you are not going to be able to start your car right up. "I would spin the engine over then flip the ignition and fuel on and she fires right up" how if the bowls are dry? Its gonna take a few seconds to fill the bowls even with ignition/pump on. Sure engine cranking will prime oil pressure but you have an electric pump that's not going anywhere without power and that is your ignition circuit that's not on. IF you lose control of your magneto's kill switch (wire comes loose, switch fails to ground) and you don't have your electric fuel pump on its own control circuit, how are you going to kill the motor? Aw, I give up. If you find an answer you like, share it.
 
No Sir !! High fuel pressure is the exact reason why injected vehicles run inertia switches. Running efi pressure on most vehicles are 40 to 60 psi. Some higher. None efi 4 to 6 psi ! None efi vehicles that have mechanical pumps works off the ignition switch by default. When the motor is not running the mechanical fuel pumps do not work !!

Well you are full of crap. Lots of cars had electric pumps and carburetors. And those cars almost always had an oil pressure cutoff switch for safety. Try for example about a 78 Toyota pickup. I may be off on the year two or three. There are others.

I'm done with you. This conversation is pointless. Go wire the damn thing with jumper cables for all I care. Or maybe knob and tube

knob-and-tube-IV.jpg
 
I prefer a switch that operates separate from the ignition (through a relay). Helps when performing compression tests (pump doesn’t run while cranking) and priming the fuel bowls before cranking the motor if the car has been sitting a while or the fuel has evaporated out from heat. But either method of wiring will work fine.
 
Always run a relay to power anything that is switched by the ignition... Just my 2 cents

Those ignition feed wires love to melt when load gets heavy
 
The other day I was driving my car and went to the store. Came out hit the ignition and click, click click.... (DAMMIT)
Reached up, flipped off the fuel pump and she fired right off.

It's not a reason to do it but it sure did come in handy that day.
I can pull my line off the carbs and fill a gas can, I can empty my fuel cell for storage, i can run my carbs dry.

All my switches are over head on the halo bar so everytime I start and shut down I feel like I'm firing up a dam jet.

:)
 
What? you misunderstood my whole post. If your bowls are dry and you have an electric pump (Been there like every morning with a TQ on a 340) and they are on the same circuit as your ignition, you are not going to be able to start your car right up. "I would spin the engine over then flip the ignition and fuel on and she fires right up" how if the bowls are dry? Its gonna take a few seconds to fill the bowls even with ignition/pump on. Sure engine cranking will prime oil pressure but you have an electric pump that's not going anywhere without power and that is your ignition circuit that's not on. IF you lose control of your magneto's kill switch (wire comes loose, switch fails to ground) and you don't have your electric fuel pump on its own control circuit, how are you going to kill the motor? Aw, I give up. If you find an answer you like, share it.
Lets keep this simple dude ! My god this is not rocket science . 1) if your fuels bowls are dry everytime you go to start this car !! Fix your car dude. 2) if your fuel bowels are dry what makes you think that if the ignition and fuel pump are on the same switch your fuels bowels are not going to fill up. At some point and time you are going to use some intelligence here. I know you want to be right here. But you have still not listed one valid reason why the fuel pump and ignition can't be on the same switch. And Sir I know there is a reason why most people do it . I just don't know a valid one that anyone has come up with. And I apologize to you and anyone else on this thread if I have offended you. Sometimes I come across the wrong way. My quest here is to answer this question with a valid reason.
 
I always wire them on their own, with a relay and switch. I've had floats stick while driving, or wanted to run the carb empty, or whatever and it's an easy way to do it when you can turn the switch off.
 
Well you are full of crap. Lots of cars had electric pumps and carburetors. And those cars almost always had an oil pressure cutoff switch for safety. Try for example about a 78 Toyota pickup. I may be off on the year two or three. There are others.

I'm done with you. This conversation is pointless. Go wire the damn thing with jumper cables for all I care. Or maybe knob and tube

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Well im glad your done with me and this thread . obviously this thread is way over your pay grade. 1) the thread is about ignition/ fuel pump being one switch . 2) oil pressure sending unit has nothing to do with the ignition and fuel pump being on the same switch . 3) if your engine dies cause you have low oil pressure the oil sending unit will cut the engine off. And all that is fine and great. But still has nothing to do with why the ignition and fuel pump can't be on one switch. Thank you Sir for responding . you have an extremely bad attitude towards a question that I ask. Cause you cant answer the question either. Which I do understand. I'm 53 yro and have been racing all my life . and will say most cars are wired this way. Why I don't know. But I so have a call in to NHRA to ask them what the rule says. And once again apologies for upsetting you. Was not my intention. Just would like to know why its done this way.
 
I always wire them on their own, with a relay and switch. I've had floats stick while driving, or wanted to run the carb empty, or whatever and it's an easy way to do it when you can turn the switch off.
Once again factual answer . thank you . me personally that still doesn't fit into a logit why . but it does make some sence. To me its a safety reason. Just like the cut off switch on the back of the car. There will be 10 thousand reasons why you shouldn't have to have one of those ethier. The same 10 thousand reasons why you should wire your ignirion/ fuel pump together.
 
I prefer a switch that operates separate from the ignition (through a relay). Helps when performing compression tests (pump doesn’t run while cranking) and priming the fuel bowls before cranking the motor if the car has been sitting a while or the fuel has evaporated out from heat. But either method of wiring will work fine.
FYI you do know that you do compression test without the ignition and fuel being on anyway on all cars. And your fuel bowls will still fill up with your ignition being on or off the carburetor bowls that are empty of fuel they don't care whether they ignition is or not. And if you want to prime your oil pump weill leave the ignition and fuel pump off and just turn the motor over until the oil pump is primed.
 
FYI you do know that you do compression test without the ignition and fuel being on anyway on all cars. And your fuel bowls will still fill up with your ignition being on or off the carburetor bowls that are empty of fuel they don't care whether they ignition is or not. And if you want to prime your oil pump weill leave the ignition and fuel pump off and just turn the motor over until the oil pump is primed.

I actually have my son crank the motor with the ignition key when doing a compression test, you could always jump the starter relay under the hood but I’d rather not.

The ignition doesn’t trigger on my car when I do a compression test using the key as I can either hit the ignition kill switch (NHRA requirement for having my battery in the trunk) or I can pull the fuse out of my digital ignition box when I perform a compression test.

You are correct that the fuel bowls will still fill with the pump wired with the ignition but the pump would also be running if I had the radio on and the motor off which I do not want to happen.

I also look at this as a theft prevention system as a potential thief wouldn’t be able to drive very far without having the electric fuel pump on, my switch is mounted in the map light location so odds are pretty slim that they would turn it on.

Never had an issue priming my oil pump but I can tell you that California’s wonderful new gas blend will evaporate really quick from your fuel bowls so it’s nice to hit the fuel pump and prime the bowls before firing the motor as modern pump gas is formulated to be under pressure (fuel injection, not sitting in vented fuel bowls).

Like I said, either way will work, this is just my preferred method.
 
..Fix your car dude.. At some point and time you are going to use some intelligence here... I apologize to you and anyone else on this thread if I have offended you. Sometimes I come across the wrong way. ..

Bingo...
 
If u are gonna race at an AHRA or NHRA track u need to have the fuel and ignition on separate circuits. And if u r going to check for spark or fuel problems u certainly don’t need the other circuit to be running. I think the best way is to have the crank circuit on a separate circuit also. Make sure u fuse each circuit with the appropriate rated fuse Kim
 
I have both my fuel pump and ignition box power wires tied into a single disconnect/kill switch (individual fuses for each) and have passed tech at both of my local tracks. Might have slightly different rules for other classes but for the brackets I run (and ET) you only need to kill the ignition and fuel pump (killing the motor of course) when the disconnect is switched off. My cranking circuit is independent of the disconnect though.
 
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