1986 Mustang Gt Not Cranking Over

Njizzo · Feb 22, 2017

I've recently relocated my battery to the trunk of the car and since then it will not turn over. When I turn the key the fuel pump goes on and everything in the car works like the a/c, lights, windshield wipers, etc. I purchased a new bwd select starter solenoid and I believe I hooked everything up right. Any info would be very helpful, thank you.

General karthief · Feb 22, 2017

I will move this to the 50 tech forums so you can get some help

General karthief · Feb 22, 2017

Describe what you used and how you did the relocation of the battery.
You need a large cable from the battery to the front of the car, and you have to make sure you grounds are large from battery to frame and from there to the engine block. I'm thinking 1 gauge or 0 gauge cable.
Explain how you did it and members will help you out.

Mustang5L5 · Feb 22, 2017

Do you have voltage on the post from the battery, and do you get continuity across the two post when you attempt to start?

You could possibly have too much of a voltage drop from the battery to the terminal as well. Could also be how you grounded it. Need to explain howyou wired it

Njizzo · Feb 22, 2017

I grounded the battery negative to the body of the car and sanded the area down to bare metal. The battery positive goes to one post of the starter solenoid the other post goes to the starter motor.

Njizzo · Feb 22, 2017

I grounded the battery negative to the body of the car and sanded the area down to bare metal. The battery positive goes to one post of the starter solenoid the other post goes to the starter motor.

Njizzo · Feb 22, 2017

Njizzo · Feb 22, 2017

Mustang5L5 said:
Do you have voltage on the post from the battery, and do you get continuity across the two post when you attempt to start?

You could possibly have too much of a voltage drop from the battery to the terminal as well. Could also be how you grounded it. Need to explain howyou wired it

I think i know what the problem is now... i used 6 gauge car battery cable. do i need a thicker cable to run it back to the trunk? Thanks.

General karthief · Feb 22, 2017

Yes, 1 gauge at least and you also should bolt a ground from the motor to the frame using the same gauge as the positive, most people run a ground, again same size, from your frame ground by the battery to the engine block and from there to the frame, all using the same 1gauge cable.

stykthyn · Feb 22, 2017

1 gauge like suggested.
@jrichker had a good write up for a battery relocation.

General karthief · Feb 22, 2017

stykthyn said:
1 gauge like suggested.
@jrichker had a good write up for a battery relocation.

I couldn't find it, when he responds I'll find out where it's at.

jrichker · Feb 22, 2017

As suggested...

Rear mounted battery ground wiring. Follow this plan and you will have zero
ground problems.

One 1 gauge or 1/0 gauge wire from battery negative post to a clean shiny spot on the chassis near the battery. Use a 5/16” bolt and bolt it down to make the rear ground. Use a 1 gauge or 1/0 gauge wire from the rear ground bolt to a clean shiny spot on the block.

One 4 gauge wire from the block where you connected the battery ground wire to the chassis ground where the battery was mounted up front. Use a 5/16” bolt and bolt down the 4 gauge engine to chassis ground, make sure that it the metal around the bolt is clean & shiny. This is the alternator power ground.

The computer has a dedicated power ground wire with a cylindrical quick connect (about 2 ½”long by 1” diameter. It comes out of the wiring harness near the ignition coil & starter solenoid (or relay). Be sure to bolt it to the chassis ground in the same place as you bolted the alternator power ground. This is an
absolute don’t overlook it item for EFI cars
Note: The quick disconnect may have fallen victim to damage or removal by a previous owner. However, it is still of utmost importance that the black/green wires have a high quality ground..

Picture courtesy timewarped1972

Crimp or even better, solder the lugs on the all the wire. The local auto stereo shop will have them if the auto parts store doesn't. Use some heat shrink tubing to cover the lugs and make things look nice.

Some racing associations require a battery cutoff switch. If the track near you is one of them, here's the best practice.

For a battery cut off switch, see http://www.moroso.com/catalog/categorydisplay.asp?catcode=42225
is the switch http://www.moroso.com/catalog/images/74102_inst.pdf is the installation instructions.
Use the super duty switch and the following tech note to wire it and you will
be good to go.

Use the Moroso plan for the alternator wiring and you risk a fire. The 10 gauge wire they recommend is even less adequate that the stock Mustang wiring.

There is a solution, but it will require about 40' of 18 gauge green wire.

Wire the battery to the two 1/2" posts as shown in the diagram.

The alternator requires a different approach. On the small alternator plug there is a green wire. It is the sense lead that turns the regulator on when the ignition switch is in the run position. Cut the green wire and solder the 40' of green wire between the two pieces. Use some heat shrink to cover the splices. See http://fordfuelinjection.com/?p=7 for some excellent help on soldering & using heat shrink tubing.

Run the green wire back to the Moroso switch and cut off the excess wire. Try to run the green wire inside the car and protect it from getting cut or chaffed. Crimp a 18 gauge ring terminal (red is 18 gauge color code for the crimp on terminals) on each wire. Bolt one ring terminal to each of the 3/16" studs. Do not add the jumper between the 1/2" stud and the 3/16" stud as shown it the
Moroso diagram.

How it works:
The green wire is the ignition on sense feed to the regulator. It supplies a turn on signal to the regulator when the ignition switch is in the Run position. Turn the Moroso switch to off, and the sense voltage goes away, the voltage regulator shuts off and the alternator quits making power.

The fuse & wiring in the following diagram are for a 3G alternator. The stock alternator uses a dark green fuse link wire that connects to 2 black/orange wires. Always leave them connected to the starter solenoid even if you have a 3G alternator.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

Njizzo · Feb 22, 2017

karthief said:
Yes, 1 gauge at least and you also should bolt a ground from the motor to the frame using the same gauge as the positive, most people run a ground, again same size, from your frame ground by the battery to the engine block and from there to the frame, all using the same 1gauge cable.

Thank you for the feed back, ill try to get a hold of some 1 gauge this week and also bolt some wire from the block to the frame.

1986 Mustang Gt Not Cranking Over

Njizzo

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General karthief

wonder how much it would cost to ship you a pair

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

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General karthief

wonder how much it would cost to ship you a pair

stykthyn

I want to measure mine. It doesn't look that tall.

General karthief

wonder how much it would cost to ship you a pair

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1986 Mustang Gt Not Cranking Over

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wonder how much it would cost to ship you a pair

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

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wonder how much it would cost to ship you a pair

I want to measure mine. It doesn't look that tall.

wonder how much it would cost to ship you a pair

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