Engine Hard start once engine is hot?

91GTstroked

Active Member
Jun 14, 2007
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Hey guys,

Just ran into some trouble today. I only drove the car for about 10 minutes, car was at operating temp. I pulled into a shaded parking lot and did a little detailing on the car.

After about 10 minutes I tried starting the car. It initially wouldn't start, I tried about 4-5 times, then let it sit for about 10 more minutes. It eventually started. The starter seemed to crank slower. It is a sve mini starter that was installed last October 2018. It also has a heat blanket around it.

My autometer volt gauge was only showing 10 volts while cranking it over. The battery is mounted in the trunk, I was told it's fairly new from the previous owner. I'll probably have it tested.

What is suggested for CCA with a battery mounted in the trunk?

Recently replaced items are, plugs, wires, distributor cap/rotor, fuel filter, ect sensor, and fuel pressure regulator.

It has a old msd 6a ignition box and coil. I would think those either work or they don't?

I also have a TFI relocation kit I plan on installing. Could a weak fuel pump create this?

I also plan on checking the timing, but need to buy a timing light.


Any help would be greatly appreciated!
 
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Vinnyb89

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edit since I see you have a cover most likely not heat soak, but i just went over this with mine and it was my timing I had it set at 13 degrees btc Thinking im in the NHRA. I turned it down to 9 and its better. I think 6-8 degrees is normal for those motors.

wouldnt hurt to go over your connections anyways.
 
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91GTstroked

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Jun 14, 2007
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If its only when its hot it could be heat soak from headers, but i just went over this with mine and it was my timing I had it set at 13 degrees btc Thinking im in the NHRA. I turned it down to 9 and its better.
I do have bbk long tube headers. I'll verify my timing. I hope the starter isn't getting heat soaked. It will be hard to go anywhere.

My car has 306, gt40x heads, e303 can and such. Just not sure where I should have timing. I've heard 12-14.
 

Vinnyb89

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Aug 17, 2019
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I do have bbk long tube headers. I'll verify my timing. I hope the starter isn't getting heat soaked. It will be hard to go anywhere.

My car has 306, gt40x heads, e303 can and such. Just not sure where I should have timing. I've heard 12-14.

Im shortys headers 306, e7s 1.7 cobra rockers,comp xe 268h I thought the same for timing but it was a no go. Id definitely Get a timing light and just confirm your in a good range.
 
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91GTstroked

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Im shortys headers 306, e7s 1.7 cobra rockers,comp xe 268h I thought the same for timing but it was a no go. Id definitely Get a timing light and just confirm your in a good range.
Hopefully I can get one tomorrow at a auto parts store. I'll check connections on the starter as well.
 

TOOLOW91

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edit since I see you have a cover most likely not heat soak, but i just went over this with mine and it was my timing I had it set at 13 degrees btc Thinking im in the NHRA. I turned it down to 9 and its better. I think 6-8 degrees is normal for those motors.

wouldnt hurt to go over your connections anyways.
Stock is 10 degrees . 6-8 is too retarded . 12-14 is the norm base using premium fuel . Daily drove drive my car like this no issues so something else must be your culprit here
 

TOOLOW91

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Hey guys,

Just ran into some trouble today. I only drove the car for about 10 minutes, car was at operating temp. I pulled into a shaded parking lot and did a little detailing on the car.

After about 10 minutes I tried starting the car. It initially wouldn't start, I tried about 4-5 times, then let it sit for about 10 more minutes. It eventually started. The starter seemed to crank slower. It is a sve mini starter that was installed last October 2018. It also has a heat blanket around it.

My autometer volt gauge was only showing 10 volts while cranking it over. The battery is mounted in the trunk, I was told it's fairly new from the previous owner. I'll probably have it tested.

What is suggested for CCA with a battery mounted in the trunk?

Recently replaced items are, plugs, wires, distributor cap/rotor, fuel filter, ect sensor, and fuel pressure regulator.

It has a old msd 6a ignition box and coil. I would think those either work or they don't?

I also have a TFI relocation kit I plan on installing. Could a weak fuel pump create this?

I also plan on checking the timing, but need to buy a timing light.


Any help would be greatly appreciated!
Test the battery , check the terminals, hopefully the cable is correct size . A lot of items come into play here . I don’t believe timing is one of them . 20 plus years guys have ran 12-14 base timing with no issues in these cars .

Check grounds as well
 

91GTstroked

Active Member
Jun 14, 2007
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Test the battery , check the terminals, hopefully the cable is correct size . A lot of items come into play here . I don’t believe timing is one of them . 20 plus years guys have ran 12-14 base timing with no issues in these cars .

Check grounds as well
Thanks. I haven't verified the timing since I bought the car in May. I did replace the balancer, that shouldn't matter though.

The battery has 580 cca, wondering if it should be more since it's in the trunk. It started just fine on a cold start again this morning.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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I agree with toolow91, with a rear mounted battery the juice has to travel a long way and connections can degrade over time. Charge up the battery, do a voltage drop test on all the cables, for help with this go to the tech/how to threads and hit the no crank checklist.
 

TOOLOW91

If you're the village idiot what's that make me?
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Thanks. I haven't verified the timing since I bought the car in May. I did replace the balancer, that shouldn't matter though.

The battery has 580 cca, wondering if it should be more since it's in the trunk. It started just fine on a cold start again this morning.
580 is definitely a little light . They need all the help they can get from the trunk
 

91GTstroked

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Jun 14, 2007
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Thanks guys, I think I should try a 800 cca battery. But which one?

Also can't a weak fuel pump cause hard starting? I have a new 255 walbro I was going to install at some point.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Yes, that is one symptom.
As far a battery brands (?) If that is what you are asking not much difference in brands cept maybe price points, I use Interstate batteries exclusively. It will come down to locations for warranty/replacement.
 
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Boostedpimp

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I personally would troubleshoot the battery, gauge of wire, and length of wiring used for the relocation. Perform the voltage drop test and go from there. If it's not the wiring, grounds or battery then it's most likely heat soak scenario since you have longtube headers.

Check the TFI is a good suggestion as well

I wouldn't put much faith in it being a timing or fuel pump issue yet... neither of those would change from cold to warm engine
 
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91GTstroked

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This is the battery. I tested it with this solar unit after the car sat overnight. This device said battery was weak. Then I started the car, ran it for a few minutes and checked again. Then it said it was good. Still having it checked out on Friday.

The battery cable is 1/0 gauge.

IMG_20190820_083957272_zpswy2q4td7.jpg
 

91GTstroked

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Jun 14, 2007
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Some have mentioned that it could be the sve mini starter. Some mentioned that a normal sized starter is better insulated.

Not sure.
 

jrichker

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Rear mounted battery wiring recommendations

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.






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.


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

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
ground.jpg


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.
 

91GTstroked

Active Member
Jun 14, 2007
201
56
38
Rear mounted battery wiring recommendations

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.






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.


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

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
ground.jpg


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.
This problem I'm having only happened to me yesterday. I've been talking with one of the previous owners that did most of the work. He said that he's never had this problem. But it has a different starter and battery from when he owned it. He said that he had a optima red top battery that had 800 CCA vs the 580 CCA that's in there now. And also had a factory style starter vs the mini sve starter.

I'll start by checking grounds and battery. The car has a pa 200 amp alternator with a inline fuse.
 
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