Hot Start Problems/Need Help

[Bizz]

I need to take my 91 5.0 in for inspection.
Problem is once gets hot it will not start back up without a 2 hour cool down.
Here is what I have checked so far:
Ran another negative ground from the terminal to a solid ground--still slow/no crank.
Hooked up another battery--Still slow/no crank.

Then I found the small secondary negative wire going from the - Battery terminal to the bolt next to the sellonoid was getting VERY hot.
Hot enough that the tape was smoking a little.
The Negative wire assembly is brand new Ford OEM.

Can someone please chime in..
I only have one more week to get this thing through the DMV...
Oh and I searched also.. with no specific results..

 

[jrichker]

Missing grounds - check them all...

1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.

The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

3.) The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. It uses a barrel type quick disconnect connector inline with the battery ground pigtail. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.

4.) The engine mounted sensors have a common separate ground. This includes the TPS, ACT, EGR, & BAP/MAP. These sensors share a black/white ground wire that connects to computer pin 46.

5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It comes out of the fuel injector harness near the EGR valve.

6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself.

7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.

8.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally.

If you have access to a digital voltmeter and would like help diagnosing grounds, make another post and I will try to help.

 

[coreyhayman]

my old 89 iroc-z camaro with a 355 did the same thing, it ended up being the headers were making the starter way to hot, i ended up making a heatshield for it and raping it in thios special type of heat resistant stuff i got from a hvac guy i know, never did it again after that.

 

[Stang8URMPRT]

Yep, had this problem many times before. It was just a starter going bad, and after it got hot (from the exhaust) it wouldn't start again. I've MELTED starter solenoids trying to start it like this. First, make sure your timing isn't set majorly high, which can cause hot start issues. Set it anywhere form 10-14 degrees with the SPOUT connector unplugged. If that's not the problem, it's most likely a bad starter.

Nick

 

[Bizz]

Thanks,
Looks like I have a lot of "Checking" and re grounding to do.
I do have the 3G and I did not replace the secondry ground...
Ill try the main first and go down the list...
I do not have a volumeter though..
6 full tool boxes and no electrical diagnostic equip..
Looks like it may be time to go to the store .

 

[HISSIN50]

Thanks,
Looks like I have a lot of "Checking" and re grounding to do.
I do have the 3G and I did not replace the secondry ground...

See Nick's recent thread about the importance (and his observations) of upgrading the power ground, as JRichker so wisely recommends.

starting issue aside, a smoking ground is bad.

 

[cooter_11]

Another thing that can cause wires to get hot is resistance. If a ground connection is dirty or corroded, or in some cases loose, it will get hot because of the increased resistance.

Also, if your resistance checks out fine and you still have full voltage potential, you should verify the circuit can operate under a load by using a test light. This is due to the wire being frayed and just a few strands of wire holding it together. You will still have full voltage up to the location of the problem, and technically the resistance has not increased because the wire is still clean and intact. However the current carrying capabilities of the wire has diminished because you only have 2 or 3 strands of wire to carry the amperage. This can cause major headaches , and often it will short out under high heat. Most of the times voltage drop tests do not catch this problem either.

If you need to know how to test this just let me know. Good luck!

 

[QuickCapri83]

Exact same problem encountered on my 87 GT and 87 Grand Marquis I had back in the day, both times turned out to be bad starter.