Hard time starting when hot

Black Sun 5.0 · Jul 6, 2007

Title pretty much says it all. Car starts fine when it's cold, but once it's warmed up, it won't spark. Any takers on this one?

Booksix · Jul 6, 2007

Pull codes. A few people may give you some ideas that fixed there problem (I had a TFI cause this for a while) but until you pull codes (whether you get any or not) you shouldn't follow any parts replacement suggestions... Follow this link for code pulling directions:

http://forums.stangnet.com/showthread.php?t=698148

91notchbk · Jul 6, 2007

Black Sun 5.0 said:
Title pretty much says it all. Car starts fine when it's cold, but once it's warmed up, it won't spark. Any takers on this one?

-Just verify your cap and rotor look good first. Also check the plug wires especially the coil wire with an ohmeter. Check the easy stuff first.

-I would then test at the coil. On one side you should have 12v when the ignition switch is on (red/light green). The other side you should have a ground pulse (tan/yellow). You can check for 12volts with a DMM (digital mutimeter) or test light. Use a test light to check for a pulse when cranking. Attach one end to B+ and the other to tan/yellow wire at the coil.

-If you have you have both a pulse (light flickering) and 12 volts then the coil is bad. However, if you do not have a pulse then you may start leaning toward the module or pick-up coil. And you will want to test them next.

-Use the process of elimination and a diagnostic appraoch to find the root cause.

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp

88mouse · Jul 6, 2007

whats your timeing set at? my car don't like to start after it gets hot. I know my timeing is set to high.

Black Sun 5.0 · Jul 6, 2007

Good thing you bring up the timing, we just put the engine back in the car and the rest of the car was just fully re-assembled. I'm going to give it a full tune-up and readjust the timing. Thanks.

HISSIN50 · Jul 6, 2007

Spark being too advanced or retarded might keep it from starting, but it should still spark.

I do agree about pulling codes.

Do you have injector pulsing?

The TFI, PIP and coil are all likely candidates.

Good luck.

Black Sun 5.0 · Jul 6, 2007

Look at it this way: when the car is cool, or cools down a bit, it fires right up. Drive it or run it for a while, it just won't fire up. It almost seems like it's flooding, and it definitley runs rich. Smells like you're on a boat with the fumes from the thing. Funny thing was, I drive it back to the body shop (pics soon) for some final touch type work, get it there, park it, had to move it, no luck getting it started. I also noticed that it's stuttering a bit under acceleration.

jrichker · Jul 6, 2007

No spark when hot - TFI and PIP are the prime candidates. Use a noid light to look for pulse at the injectors. No pulse - PIP has failed. Pulse at injectors, TFI has failed.

Dumping the codes will often show a code 14 for a failing PIP sensor.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

See http://www.troublecodes.net/Ford/

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

89 through 95 cars have a working Check Engine light. Watch it instead of a test lamp.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/pc-7208-90-equus-digital-ford-code-reader-3145.aspx – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

91lxttrim · Jul 6, 2007

Is your battery mounted in the trunk by any chance? What is your fuel pressure set at? What size injectors?

93 LX · Jul 7, 2007

quick test. Take a can of air. Turn it upside down now it will cool things. Spray the TFI, if it fires up, bad TFI.

Allen

91notchbk · Jul 9, 2007

Jrichker has some good information to quickly test for either the PIP or the TFI. I would do exactly as he stated. If it has an injector pulse but no spark then probably TFI. No injector pulse and no spark then PIP. However, even though it is not as probable as the PIP or TFI, you may possibly have a bad coil, bad wiring, open coil wire, bad cap/rotor. I would still test each suspect part before replacing them.

The correct method to diagnose an ignition system is to test the for input and output signals and use the process of elimination to find the root cause. However, this requires a complete understanding of how the ignition system works and may be too advanced if you don't have the knowledge and tools.

What ever part you conclude to be you should do a final test to verify the suspect part. I can not count how many times guys replace parts that they think are bad and they are mistaken.

It is better to test, test, test before guess, guess, guess.

Black Sun 5.0 · Sep 5, 2007

OK, just an update on this: gave the car a full tune-up and replaced all the battery wires and added an extra 4ga ground for the battery to be sure we have proper grounding. What I realized was that since the entire car was repainted, including the engine compartment, there was no bare metal for proper grounds and the battery did not appear to be charging properly. Jumped the car, it started and I ran it for a few minutes and shut it off. Started the car again, started with no problem again. The next morning, I did the same thing, this time I figured let me run it for a bit to get up to temp. and charge the battery for a while. After running the car for about 20-25 minutes, I shut it down, went to restart, car behaved like the battery was almost dead and wouldn't start. I let the car cool for a while, I was able to restart. So, are we thinking TFI here?

HISSIN50 · Sep 5, 2007

If the car was acting like it had a nearly dead battery, that wouldnt necessarily suggest TFI.
You cleaned up all the other grounds so they are functional now? I still wonder if the stalling isnt related to the battery/charging issue.

When the car stalls, can it start right back up? If not, do you have spark while cranking it over? If so, the TFI is fine. Fix the charging issue and the rest might fix itself.

Good luck.

Black Sun 5.0 · Sep 5, 2007

It's not stalling. Idles great. Battery is charging after the grounds were cleaned up.

Black Sun 5.0 · Sep 6, 2007

HISSIN50 · Sep 6, 2007

I'm having a hard time deciphering this thread. If the only issue is with cranking while hot, consider the starter being on the outs. Also, the performance of a bad cable will degrade as the cable itself gets hot (exhaust heat).

68keyblr · Sep 6, 2007

Just had the exact same problem. It was the starter! I also replaced the battery ground while I was at it and that made a big difference as well.

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