Please help....new fuel pump wiring

jobofly

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Hey guys, I just installed my new carter p4389 electric fuel pump. I wired it through a 3 prong safety Safety switch. The power for the fuel pump is coming from the P terminal on the safety switch, the I terminal goes to the ignition switch and the S terminal goes to the coil. The boat will start but on run for about 10 seconds then it dies. I'm guessing the the fuel pump is getting power while cranking but not after I stop cranking. I do have an inline fuse going to the fuel pump. It's a 15 amp but the fuel pump calls for a 10 amp. Would that make a difference? please help me figure this out
 

gm280

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If this engine had an electric fuel pump on it before, then wire it like the old one you replaced. If this is the first time installing an electric fuel pump on this engine, then there are some things you need to consider. If the engine doesn't crank or is running and stalls, the ignition switch in on, and the fuel pump would continue to run as well. And if that happens, you can easily flood the engine with gas very quickly. A better option is to install an oil pressure switch and once oil pressure builds up the fuel pump turns on. That way if the engine dies, the fuel pump stops as well... A more safer way to install an electric fuel pump. As for the 15 amp fuse circuit, it will be okay. You could drop to a 12 amp fuse for quicker action if the pump shorts, but 15 amp will also work..that is if the wire can support 15 amps! JMHO!
 

alldodge

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Hey guys, I just installed my new carter p4389 electric fuel pump. I wired it through a 3 prong safety Safety switch. The power for the fuel pump is coming from the P terminal on the safety switch, the I terminal goes to the ignition switch and the S terminal goes to the coil. The boat will start but on run for about 10 seconds then it dies. I'm guessing the the fuel pump is getting power while cranking but not after I stop cranking. I do have an inline fuse going to the fuel pump. It's a 15 amp but the fuel pump calls for a 10 amp. Would that make a difference? please help me figure this out

Swap the S and I terminals, you have it backwards. The S (N or NC) terminal is the start terminal, and I (NO) is the ignition (used after the engine is running)
Fuel pump, electric.jpg
 

jobofly

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Swap the S and I terminals, you have it backwards. The S (N or NC) terminal is the start terminal, and I (NO) is the ignition (used after the engine is running)

Ok the I terminal goes to the ignition and the S terminal goes to the coil. Those should be reversed?
 

alldodge

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So it's ok that it is wired to the coil and not to the starter?

The P terminal is the center wiper for the switch. The P terminal goes to the pump. When your engine is trying to start you want 12V coming from your starter solenoid terminal applying power to the pump. Once the engine starts the oil pressure comes up and applies power coming from the coil to the I terminal which keeps the pump running
 

jobofly

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The P terminal is the center wiper for the switch. The P terminal goes to the pump. When your engine is trying to start you want 12V coming from your starter solenoid terminal applying power to the pump. Once the engine starts the oil pressure comes up and applies power coming from the coil to the I terminal which keeps the pump running

Ok awesome, I will swap these tomorrow and let you know how it goes. Thanks for your help
 

jobofly

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Ok I switched these around, I'm not sure the P I S is actually labeled right. I have the wire from the ignition going to the S terminal, the wire from the coil to the P terminal and the wire from the fuel pump to the I terminal. It started right up and ran. I let it run for about 10 minutes then shut it down. Thanks for your help
 

alldodge

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That's how I wired it the first time and it didn't work. I tried it the way all dodge said and that didn't work, this is the only way it worked

No you didn't according to your first post
The power for the fuel pump is coming from the P terminal on the safety switch, the I terminal goes to the ignition switch and the S terminal goes to the coil.

You needed to switch the I and S terminals only, not the P terminal. According to your statement you put them both to the same terminal, but your explanation said differently
 
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smokeonthewater

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24oy7uc.jpg
 

smokeonthewater

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As you described in your first post the wire from the coil would be powering the pump as soon as you turned the key on and the pump would be running even though the engine wasn't (bad news, defeats the whole point in having the safety switch) .... Then when it got oil pressure it would switch to the ign powering the pump and it should have kept running.... I suspect that you connected the ign wire incorrectly and didn't have power on it with ign on.
 
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