Quantcast 1994 F150 inline 6 weak charging system - Ford Truck Club Forum








New Posts



Remember Me?
       Join for free!




FTC Toolbar

Social Sites


Ford Truck Club Forum > FORD F-100 | F-150 SERIES > 1992-1996 Ford F150

Welcome to FordTruckClub.net
Welcome to FordTruckClub.net, the internet's premier Ford truck community! You are currently viewing our boards as a guest which gives you limited access to view discussions and access other forum features. By joining our free online community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple, and absolutely free so please, join our community today!

Forgot your password? click here.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools Search this Thread Display Modes
Old August 14th, 2012, 01:50 PM
davigf's Avatar
davigf davigf is offline

Join Date: Aug 2012
Posts: 6
Likes : 0
Liked 0 Times in 0 Posts
Default 1994 F150 inline 6 weak charging system

Replaced battery, alternator (under Autozone warranty), and heavy wire connector (assembled by a professional). Charging system still weak at idle, under A/C load. Lights also affect it, but not nearly as much as A/C. Problem just started last week. Old alternator tests good on the bench at Autozone after failing an on board test (bad voltage regulator). New alternator fails the same on board test for the same reason. Have had it suggested that I upgrade to a 3G alternator. Need good instructions for re-wiring, if that is the best path forward.

Old August 14th, 2012, 01:59 PM
Booba5185's Avatar
Booba5185 Booba5185 is offline

Join Date: Dec 2011
Location: Ava, MO
Posts: 2,705
Images: 747
Likes : 13
Liked 31 Times in 28 Posts

You already have a 3G, but there is a more powerful 3G (130amp vs. your 95 AMP) available. When you say weak charging system, what do you mean? Use a multimeter to check your voltage and post your results. What do you mean by wire connector?

89 F-150 5.0l AOD 2x4, 3.55 LS(+4), Converted to HO Roller, 3g Alt, GT40Ps, Y-pipe, Rerouted PCV, Dual Taurus E-fans, Explorer Injectors, Remote ICM, DIY Cold air, Rubber Vacuum System, Tranny cooler, Remote Tranny filter, Saginaw P\S swap, F350 Brakes, more.

Old August 17th, 2012, 11:24 AM
davigf's Avatar
davigf davigf is offline

Join Date: Aug 2012
Posts: 6
Likes : 0
Liked 0 Times in 0 Posts

I have a 75 amp alternator stock. Weak - my in dash meter normally runs vertical, or just to the right of verticle, toward the 18v side. Whenever that meter runs to the left of center, historically, my charging system is defective. That is happening at idle, sometimes, and only under the conditions of a full load (lights and A/C on). Sometimes, it now starts out low, and as I rev the engine, it moves to the center. I changed out both connectors on the alternator, a d shaped connector that has the voltage meter green / red lead, and the power connector, a larger rectangular connector. I had a profefssional make the connections. I do not want a fire hazard. That seemed to help the situation a lot, but it is still going low, just not as often. Low - when my voltage meter on the truck moves toward the lower voltage, an independent meter reads 13.06 volts across the battery. When the in dash meter is centered, the independent reading across the battery is at least 13.5 volts. Here is the thing. Autozone runs their test equipment on my charging system, and it gives them a voltage regulator fail code at idle, under full load on the old alternator, and on a new one. Those same alternators will pass Autozone's bench test with flying colors. I am about to drive this truck 1000 miles to a new job. I cannot afford to kill a battery in the middle of nowhere. I do not think that will actually happen, but my in dash voltmeter has NEVER behaved this way without a REAL problem with the charging system. What I cannot figure out is, what has changed in the charging system to produce this behavior, which is new. Could other wiring in the system, that I have not changed be so old that the resistance is just increased after so much exposure in Texas heat? I am just confused.

Last edited by davigf; August 17th, 2012 at 11:34 AM. Reason: add information
Old August 17th, 2012, 11:34 AM
davigf's Avatar
davigf davigf is offline

Join Date: Aug 2012
Posts: 6
Likes : 0
Liked 0 Times in 0 Posts

By the way, I understand exactly what I need to do to change to a 130 amp alternator. RJM Injection Technology has some nice wiring kits to make the necessary changes. One problem, for my truck, it does NOT appear that the 130 amp alternator would really fit. The mounting hole spacing does not appear to be close. The mount bracket has an extra lower mounting hole, threaded and all, and it takes the bolt just fine. But, if you look at the 130 amp alternator, its mounts are 180 degrees apart. The mounts on my 75 amp alternator are not, and the offset that appears to be needed to accommodate the 130 amp alternator is not nearly enough on the bracket. This is a secondary issue at this point. I do not plan to make the change at this time. I am fearful that whatever is dragging down the 75 amp alternator (sometimes) will have a similar affect on the 130 amp alternator. Another question, what minimum amperage should I measure at the battery under a full load (ac and lights, at idle)?
Old November 5th, 2012, 10:29 PM
MaiNiaC's Avatar
MaiNiaC MaiNiaC is offline

Join Date: Nov 2012
Posts: 1
Likes : 0
Liked 0 Times in 0 Posts

Was this ever resolved? I have the same problem in my 87. All stock.
Old November 6th, 2012, 09:25 AM
ASwaff400's Avatar
ASwaff400 ASwaff400 is offline

Join Date: Nov 2009
Location: St. Pete FL
Posts: 1,890
Images: 1013
Likes : 4
Liked 17 Times in 14 Posts

im only throwing this out there, but how old is your battery? whats the CCA of it?

a few years back i had a battery that wasnt taking a charge. ended up frying the alternator, new alternator and battery, problem solved


'95 F150 XLT, reg cab long bed, swapped 351w,
4.56 gears, 4-link SAS, 14" coil overs.

SAS Thread!!!

'04 F250 Lariat, crew cab short bed 4x4 6.0L PSD, 3.73 gears, straight piped,
sinister coolant filter, welded egr, CAT EC-1 coolant, blue spring.
60 gallon fuel tank/tool box, SCT X4 w/IDP custom tunes, SOON TO BE STUDDED!!

a bunch of boats

Last edited by ASwaff400; November 6th, 2012 at 09:31 AM.
Old November 6th, 2012, 01:50 PM
JSoko's Avatar
JSoko JSoko is offline


Join Date: Jun 2009
Location: Northwest Georgia
Posts: 14,999
Images: 627
Likes : 33
Liked 185 Times in 167 Posts

do what Booba said
do a voltage check

also most parts stores & WalMart will do a free charging system check

For Those Who Fought For It...
Freedom Has A Taste The Protected Will Never Know.

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

(View-All Members who have read this thread : 13
ASwaff400 , BigBlue79 , Booba5185 , davigf , DoubleDee , Drewz94 , JSoko , MaiNiaC , Red91 , rikard , Russo2 , Scorekeeper58 , The Frankster

Similar Threads
Thread Thread Starter Forum Replies Last Post
1994 Arizona Bronze supercab F150 inline6 davigf New Member Introductions 5 August 14th, 2012 10:54 PM
Weak brakes bikertrash3531 1973-1991 Ford F150
46 February 9th, 2012 12:12 AM
95 instrument cluster swap = alternator not charging nightshade 1992-1996 Ford F150
6 January 27th, 2012 08:59 AM
2001 F150 Stock air intake system screwon23s Auto Parts For Sale
5 December 17th, 2009 12:59 AM
1994 F150 Engine Wiring Harness 1994F150Green4x4 1992-1996 Ford F150
1 November 10th, 2009 09:21 PM

1994 , charging , f150 , inline , system , weak

Forum Jump

FordTruckClub.net is not authorized, endorsed or affiliated with the Ford Motor Company
or any of their subsidiaries. Ford® is a registered trademark of the Ford Motor Company

Powered by vBulletin® Version 3.8.6 Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.