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Discussion Starter #1
I’ve got an aeromotive 340LPH pump in my 90 coupe. Just wondering does the pump require the upgraded wiring harness that aeromotive offers?

How many amps is the oem fuel pump system vs the aeromotive?

Thanks!


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It would be cheap insurance to upgrade the wiring, especially if you're turbo/supercharged. I think I spent 2 hours and about $25 on 15 foot rolls of 12 ga wiring for both the hot and ground, a fuse holder, and 4 pin relay from auto zone. I drilled out the holes where the stock wiring enters the fuel hat, added grommets, and ran the 12 ga right to the pump. Now if I blow a head gasket it's because of my tuning skills, and not because of 30 year old 14ga factory wire.
 

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No.

Aeromotive draws 15a, the factory wiring will be fine. I’ve seen the hellcat pump wired using factory wiring and everything was fine.

That being said, you can do up your own relay using the factory wiring as the trigger wire for like $15 in relay, wire, and terminals.
 
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Wowza... abso frikn lutely!!!

Simple... look up amp draw and length, wire guage chart.

I needed 10 quage for the run. Yes 14 guage is coming out of the pump... that's fine for 3 feet of amp draw.
 

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Discussion Starter #5 (Edited)
No.

Aeromotive draws 15a, the factory wiring will be fine. I’ve seen the hellcat pump wired using factory wiring and everything was fine.

That being said, you can do up your own relay using the factory wiring as the trigger wire for like $15 in relay, wire, and terminals.
Aeromotive told me the stock pump pulls 5amps. their pump pulls 12-15. So I don’t know what the truth is.


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Aeromotive told me the stock pump pulls 5amps. Vw the 15am their pump pulls


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Aeromotive sells fuel pump wiring kits, so it’s no surprise they’ll tell you new wiring is recommended.

I can tell you with 100% certainty that if the factory wiring is in good shape, it’ll work fine for a 340lph pump. I’ve personally seen it feed bigger pumps than that using the factory wiring without a hiccup. 15amps using 14ga wire for the length of the run is fine.

Amazon sells southwire wire and relays for cheap though. I wouldn’t tell somebody not to install their own relay with bigger wiring, but it’s not required.
 

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Aeromotive told me the stock pump pulls 5amps. their pump pulls 12-15. So I don’t know what the truth is.


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stick a meter on your wiring and find out!

stock pump pulls more than 5amps, i measured IT.

even if it dont turn you car into flames, look at the pump output when you reduce voltage.
 

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Yeah, i measured IT. Roger

It can't hurt to use a thicker gauge. Even the higher volume Walbro's will come with pre-molded smaller gauge but I would splice in 12-10 AWG if you can.
 

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thanx tech tips

those types of tips, cant hurt, splendid!

why not call walbro to!!
 

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Yea, I have melted pigtails and wiring with 340’s.
 

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After burning up a new 340lph pump on a bone stock car; I decided that I should check the voltage at the pump just outside of tank. There was just under 12 volts. Not good! I would drive the car 45 minutes to an hour and it would start running poorly and would barely get me home. I tested the fuel pressure when it was running terribly and the gauge showed 20psi and fluctuating. My battery shows 14.5 volts when the car is running. I had a 3v drop from power source to the pump. I installed the following and problem solved. I have 14.4v at the pump.
Heavy Gauge Fuel Pump Pigtail For 1986 - 1997 Mustangs
Painless Wiring
 
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This chart will give you an idea. You may get away with the stock wiring for a while, but if the pump draws 2-3x the amps of a stock one, I probably wouldn't chance it acting like a 'fusible link'.
 

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Discussion Starter #13
After burning up a new 340lph pump on a bone stock car; I decided that I should check the voltage at the pump just outside of tank. There was just under 12 volts. Not good! I would drive the car 45 minutes to an hour and it would start running poorly and would barely get me home. I tested the fuel pressure when it was running terribly and the gauge showed 20psi and fluctuating. My battery shows 14.5 volts when the car is running. I had a 3v drop from power source to the pump. I installed the following and problem solved. I have 14.4v at the pump.
Heavy Gauge Fuel Pump Pigtail For 1986 - 1997 Mustangs
Painless Wiring
I am positive I have this wiring as it came with my AN fuel pump hanger!


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In my 89 coupe after a day of driving it around with that same pump in it, the car would intermittently not start and there would be no fuel pressure. Long story short the wiring inside the tank burnt where it connects to the hat. Your car has 30 year old wiring and you are putting a pump 4xs bigger than the wiring was designed for I’d highly recommend upgrading it
 
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