Hot Start Woes

[ATISTANG]

Alright

when my battery was up front the car would start just fine cold, hot it would crank slightly slower(not enough for anyone to notice except for me who drove it everyday)

when i dropped my stroker in i relocated the battery to the trunk. Cold start it cranks right up with no problems, but hot start it barley cranks, most of the time not fast enough to even start the engine. I checked the voltage the other day after i shut it off hot and it was 12.3. The power cable by the solenoid was extremely hot. back in the trunk off of the batter it was warm. I hooked the battery charger up and it started a little easier.

Once it was running i checked the voltage with the fan on, and blower fan on and the voltage was at 13.7, I let it run for about 5 mins and it stayed right around 13.7. So i am pretty sure that my charging system is doing enough to where it should start.

I have the stock alternator with an overdrive pulley. stock starter. My power cable is 2 ga. I have a ground ran to the quad shock bolt, then from the quad shock bolt to the engine, then to the sway bar bracket. I also have solid motor mounts, so i am sure my ground is up to par.

Do you guys think i should go with a bigger power cable? say 1/0? 2/0?

I think what is happening is once the cable gets hot there is so much resistance in it that it kills the voltage by the time it makes it to the starter

 

[jrichker]

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..

The screwdriver points to the common body ground for the alternator, battery and computer.

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.

For a battery cut off switch, see Moroso : Category Display
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 Ford Fuel Injection How To Solder Like a Pro 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
Mustang FAQ - Engine Information 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

 

[ATISTANG]

i have it wired up like that, just my ecu ground is soldered to the battery ground

this is why i think my 2ga power cable is to small

 

[jrichker]

i have it wired up like that, just my ecu ground is soldered to the battery ground

this is why i think my 2ga power cable is to small

Look at the drawings in my post and you will see the recommended cable size is 1 or 1/0 gauge copper wire.

 

[ATISTANG]

Look at the drawings in my post and you will see the recommended cable size is 1 or 1/0 gauge copper wire.

thats what i was figuring, i am probably gonna upgrade to that and hope i dont need a 3g alt

 

[ATISTANG]

well the 1/0 cable fixed my hot start problem