Upgrading fuel pump wiring for 87-93 - Ford Mustang Forums : Corral.net Mustang Forum
 
LinkBack Thread Tools Display Modes
post #1 of 13 Old 02-07-2017, 10:59 AM Thread Starter
Registered User
 
LT1HAHA's Avatar
 
Trader Feedback: (24)
Join Date: Feb 2004
Location: Franklin, OH
Posts: 2,662
Upgrading fuel pump wiring for 87-93

Hey guys,

I'm hoping I can get some help here. I'm upgrading my in tank pump to an Aeromotive 340 stealth unit. Apparently it is a good idea to upgrade the pumps stock 14 gage wire when doing a big pump like this as the amperage is higher than the old 14 gage wire can handle sometimes. This is definitely a place where I do not want a fire.

Problem is, I'm not sure which wires to upgrade and how to do it. I'm hoping someone in here has done this mod before and can give me a step by step on how to do it.

There's not much out there on the old fox fuel wire upgrades but tons of thread on doing the later years.


91 Road Racing Fox. N/A 383W. Full MM setup front and rear with Bilstein coil-overs. 14x1.25 Wilwood 6 piston fronts with Wilwood 13x1 single piston rears.
486rwhp/ 430rwtq
LT1HAHA is offline  
Sponsored Links
Advertisement
 
post #2 of 13 Old 02-07-2017, 11:58 AM
Registered User
 
Trader Feedback: (4)
Join Date: Dec 2010
Location: Dallas/Houston
Posts: 1,756
Most people that do this just find the pump relay and run larger wire from that relay to the pump itself. you can also upsize the wire before the relay if you want.

5.0thunder is offline  
post #3 of 13 Old 02-07-2017, 11:59 AM
Registered User
 
Trader Feedback: (4)
Join Date: Dec 2010
Location: Dallas/Houston
Posts: 1,756
On a side note, idk what the deal is with Aeromotive wanting large wire. I run a walbro 450 on stock wiring without issue.
5.0thunder is offline  
Sponsored Links
Advertisement
 
post #4 of 13 Old 02-07-2017, 01:02 PM Thread Starter
Registered User
 
LT1HAHA's Avatar
 
Trader Feedback: (24)
Join Date: Feb 2004
Location: Franklin, OH
Posts: 2,662
I thought there was something about using a new relay, run new wires from new relay to fuel pump, new wire from battery to new relay, connect new wire to old fuel pump wiring to trigger new relay to come on.

Something along those lines.....


I sure hate to remove the seat as it's an aftermarket seat and a bear to get out/in with rollcage and everything. However, if that the way it is supposed to be done then that leaves little choice.

91 Road Racing Fox. N/A 383W. Full MM setup front and rear with Bilstein coil-overs. 14x1.25 Wilwood 6 piston fronts with Wilwood 13x1 single piston rears.
486rwhp/ 430rwtq
LT1HAHA is offline  
post #5 of 13 Old 02-07-2017, 02:19 PM
Registered User
 
ross2004's Avatar
 
Trader Feedback: (3)
Join Date: May 2013
Location: Staunton, Virginia
Posts: 564
The pump draws 15A, which is only good for 7' of un-deteriorated 14ga wire. Use 10ga wire for the new pump. The 10ga wire needs to be on both "sides" of the relay. That's the fused battery side coming in, and the power wire going out to the pump. Make sure you've got a good ground for the pump as well.
ross2004 is offline  
post #6 of 13 Old 02-07-2017, 02:33 PM Thread Starter
Registered User
 
LT1HAHA's Avatar
 
Trader Feedback: (24)
Join Date: Feb 2004
Location: Franklin, OH
Posts: 2,662
Ross,

So do it as I explained above with a separate relay correct? NOT running new wire from the stock relay under the seat all the way back right.


I would use the normal power wire for the stock pump as the wire that turns on the relay. Is that right

91 Road Racing Fox. N/A 383W. Full MM setup front and rear with Bilstein coil-overs. 14x1.25 Wilwood 6 piston fronts with Wilwood 13x1 single piston rears.
486rwhp/ 430rwtq
LT1HAHA is offline  
post #7 of 13 Old 02-07-2017, 03:00 PM
Registered User
 
Trader Feedback: (4)
Join Date: Dec 2010
Location: Dallas/Houston
Posts: 1,756
You can either wire in a new relay with new wiring and trigger it on with the old relay, or delete the old relay and power wiring (since it will now be dead weight) by using the oem trigger wires on a new relay with new power wires. There are a few diff ways that you can do it, each of which will perform the same in terms of current carrying capacity for the pump circuit.
5.0thunder is offline  
post #8 of 13 Old 02-09-2017, 04:34 PM
Registered User
 
ross2004's Avatar
 
Trader Feedback: (3)
Join Date: May 2013
Location: Staunton, Virginia
Posts: 564
Quote:
Originally Posted by LT1HAHA View Post
I would use the normal power wire for the stock pump as the wire that turns on the relay. Is that right
That'll work. You can run a 10ga wire straight from the battery or starter solenoid to your new relay to power the pump. Just make sure you fuse it (at the battery or solenoid).
ross2004 is offline  
post #9 of 13 Old 02-09-2017, 04:48 PM Thread Starter
Registered User
 
LT1HAHA's Avatar
 
Trader Feedback: (24)
Join Date: Feb 2004
Location: Franklin, OH
Posts: 2,662
That's what I did.

Got 2 more questions just in case anyone knows the answer for sure.

On the stock power wire and ground that feeds the pump; I am now using the stock power wire to turn on the relay. Do I also need to ground the original fuel pump grounding wire? I'm kind of assuming that wire is already grounded somewhere since it originally served as a ground for the stock fuel pump. I'm assuming I can just cut it as it is no longer needed with the new setup.


Also the original fuel pump power wire can be ran with 14 gauge wire as it will not see much amperage to just turn on the new relay, correct?

91 Road Racing Fox. N/A 383W. Full MM setup front and rear with Bilstein coil-overs. 14x1.25 Wilwood 6 piston fronts with Wilwood 13x1 single piston rears.
486rwhp/ 430rwtq
LT1HAHA is offline  
post #10 of 13 Old 02-10-2017, 01:55 PM
Registered User
 
TomR's Avatar
 
Trader Feedback: (2)
Join Date: Aug 2009
Location: Macon, GA
Posts: 4,947
Garage
A normal battery on full charge is 13.8 volts, and while charging can be over 14.5.

The reason stock #16 wires works for some people is at 15 amps the voltage drop in 10 feet is about 0.6 volts. With a fully charged 12V battery on a running alternator you'll be at least 13.2 volts.

If you change to #10 (same 10ft length) you'll be at 0.15 volts drop, so you pick up 0.45 volts.

A good fuel system has way more headroom than that.

The ground wire length to the chassis also adds to the drop, as does the fuse and the relay contacts and especially any push-on connections. But as a general rule as long as you are not on the ragged edge of pump pressure or volume, you are OK at 15A in a car with an alternator with 16 ga with voltage.

My bigger worry with 16ga would be wire heat with minor overloads. A fuse does not blow exactly at the fuse current, it can sometimes carry 2 times or more the fuse rating for a minute or more depending on temperature and the fuse type, and any holder resistance at the fuse contacts. The OEM relay is also marginal.

I am helping a neighbor clean up the mess in his car and his fuel pump has an unnecessary 5-6ft long ground lead. It could have been a foot long.


Because of the heat and safety, and because the OEM relay is out of headroom on the contacts and probably old, I'd do like someone suggested and just pull a 10 or 12 wire and use a new 30-40A relay either driven from the old system some way. But I just wanted to point out why some people have no problems. It isn't really the voltage drop that is normally the real issue, it is the head room and safety.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
89 LX. 363, single turbo, Super Vic EFI, TFS high port heads by TEA, solid roller, glide. Holley HP EFI. (exact combo varies)
TomR is offline  
post #11 of 13 Old 02-10-2017, 02:52 PM Thread Starter
Registered User
 
LT1HAHA's Avatar
 
Trader Feedback: (24)
Join Date: Feb 2004
Location: Franklin, OH
Posts: 2,662
Thanks for the reply but I think you misunderstood my question.

I am using a new relay with 10 gauge power and ground wires to power the pump. The new relay gets power straight from the battery with a 10 gauge wire and a 10 gauge wire from relay to ground. The only thing I'm using the factory wire and relay for is to tell the NEW relay to "turn on". The factory wire will now therefore only see a maximum of 5 amps since it will only be telling the new relay to turn on.

FWIW though factory fuel pump wiring is 14 gauge wire.

Thanks again for the reply though. It will hopefully help someone out in the future who runs across this thread.

91 Road Racing Fox. N/A 383W. Full MM setup front and rear with Bilstein coil-overs. 14x1.25 Wilwood 6 piston fronts with Wilwood 13x1 single piston rears.
486rwhp/ 430rwtq
LT1HAHA is offline  
post #12 of 13 Old 02-11-2017, 10:05 AM
Registered User
 
midnightlaundry's Avatar
 
Trader Feedback: (3)
Join Date: May 2004
Location: Westland, MI.
Posts: 2,142
I'll be using the stock wiring to trigger a new heavy duty relay. My battery is already in the trunk.
midnightlaundry is offline  
post #13 of 13 Old 03-15-2017, 02:21 PM
Registered User
 
Trader Feedback: (2)
Join Date: Dec 2007
Location: St. Louis
Posts: 389
What I did was......used the factory power wire to the pump to trigger a new relay that was feeding new heavier wire to the pump. Works fine no issues.
HLD-TYT is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Mustang Forums : Corral.net Mustang Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Starting without tune or calibrated maf. 89blkmustang Turbochargers 21 07-04-2018 07:47 AM
Aeru 16307 fuel pump 10Ga wiring kit ndmus88gteng General Mustang Tech 3 02-19-2016 10:56 AM
98 cobra fuel pump issue luvmystallion SVT & DOHC 9 11-15-2013 06:22 PM
carb conversion redfox89 5.0/5.8 Engine Tech 6 11-11-2013 09:20 AM
Car shut down while driving and will not restart, HELP! shdowconspiracyx 5.0/5.8 Engine Tech 15 09-10-2012 02:31 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome