Is my fuel pump wired wrong?

[EastAustinSawdust]

The previous owner of my 78 c10 installed an electric fuel pump (a Mallory Series 110). The fuel pump turns on when you turn the key to the accessory position. In other words, if I turn the accessories on, the fuel pump runs.

1. Is that right? I thought it’s not good for the pump to run it when the engine isn’t running.

2. If not, what do I do to fix it? Put it on a relay? Add a kill switch? Those are ideas gathered from some Googling. Would love more detailed instructions on how to actually do them.

Thanks!
Adam


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[75gmck25]

A fuel pump draws a lot of current, so it should always be powered by a relay.

Activate the relay using a circuit that is only on when the truck is running, not when in the accessory position. I'd have to verify for sure, but I think the wiper circuit would work (you can easily tap into it under the hood), or if you have an electric choke wire it would also work to activate the relay.

Bruce

 

[WebMonkey]

electric fuel pumps usually have a built in pressure switch.

they immediately pump up the juice until it reaches 'pressure'.

so, it may be just fine.

my 2005 dodge fires up the pump without cranking the engine.
my polaris 4 wheeler does as well.

that's all the help i can give.

sorry

 

[C10MixMaster]

The previous owner of my 78 c10 installed an electric fuel pump (a Mallory Series 110). The fuel pump turns on when you turn the key to the accessory position. In other words, if I turn the accessories on, the fuel pump runs.

1. Is that right? I thought it’s not good for the pump to run it when the engine isn’t running.

2. If not, what do I do to fix it? Put it on a relay? Add a kill switch? Those are ideas gathered from some Googling. Would love more detailed instructions on how to actually do them.

Thanks!
Adam


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75GMCK25 is rite a relay is a good idea. You should also ground the relay through a oil pressure switch, that way in the event of a accident the fuel pump quits when the engine dies.

Most fuel injected cars the computer primes the system when you cycle the key but shuts off after a few seconds, not needed for your carb. setup.

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[RoryH19]

x2, all of the FI cars I have, even my 87 R10 TBI prime the fuel system when the key is turned on.
This allows for ease of starting, similar to pressing the gas pedal first on a carb.

 

[Snoots]

75GMCK25 is rite a relay is a good idea. You should also ground the relay through a oil pressure switch, that way in the event of a accident the fuel pump quits when the engine dies.

Most fuel injected cars the computer primes the system when you cycle the key but shuts off after a few seconds, not needed for your carb. setup.

You must be registered for see images attach

X2!

 

[EastAustinSawdust]

A fuel pump draws a lot of current, so it should always be powered by a relay.

Activate the relay using a circuit that is only on when the truck is running, not when in the accessory position. I'd have to verify for sure, but I think the wiper circuit would work (you can easily tap into it under the hood), or if you have an electric choke wire it would also work to activate the relay.

Bruce

Thanks for the advice, Bruce (and others).

Any idea what kind of relay, and/or where I could go to find that info?


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[Matt69olds]

Keep it simple and safe. You could wire the pump using a oil pressure switch. No oil pressure, no fuel pump. Or try this setup.

http://www.revolutionelectronics.com/Products/Fuel_Pump.html

 

[EastAustinSawdust]

Prob should have consulted this resource earlier: the install instructions for the pump:

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Says wire it into an oil pressure switch.

I’ll have to scrounge around tomorrow. It’s night and raining and cold, not the best time to crawl into the back of my engine bay.


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[EastAustinSawdust]

Or try this setup.

http://www.revolutionelectronics.com/Products/Fuel_Pump.html

Bingo. That sounds even better!



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[Raybo135]

Bingo. That sounds even better!



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That is exactly what I was goin gto recommend. It will only run when the engine is running. Great in the event of an accident, it won't continuosly be running if the engine isn't and that would be a huge fire danger if it did run continuously!

 

[EastAustinSawdust]

Circling back. Purchased the Revolution Electronics relay. Installed it today. Works precisely as advertised. Install was pretty straightforward...connects inline with the fuel-pump-to-battery line, and also hooks into a 12v accessory circuit, the tach wire from the distributor, and ground. Had to install an optional diode (included) that runs across the + and gnd wires of the fuel pump to get it to work. Runs pump for 3 sec when accessories are on, then stops it, and then runs it again when engine runs.

I don’t have a tach, so my tach lead on the distrib was empty. Rather than trying to jam a paddle connector in there I just bought a pigtail connector: https://shop.advanceautoparts.com/p...VA9vACh0dDQxkEAQYAiABEgICw_D_BwE&gclsrc=aw.ds

Interestingly the fuel pump (Mallory 110) was already wired into a relay. A Novita RL45. No clue what it did. But it allowed the pump to run nonstop when the accessories were on, hence this whole thread.


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[Turbo4whl]

Interestingly the fuel pump (Mallory 110) was already wired into a relay. A Novita RL45. No clue what it did. But it allowed the pump to run nonstop when the accessories were on, hence this whole thread.


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What that relay would do, if it was wired correctly, keep the voltage load of running the pump, off what ever switching circuit you choose to use.

 

[AuroraGirl]

I believe what he originally asked was the pump would run in ACC, which is the switch turn before on that usually lets you run the radio and 12v plug in most cars, not sure about these trucks. But it seems he found what he was looking for.