First wont start, then wont run

[trailblazr81]

OK so I havn't driven my 2000 GT for 2 weeks and I go out to start it and it barely cranks. So I drag out the charger and then I get it started. Let it sit running for 5-10 minutes. I go to rev it up and it bogs. Then it stumbles while idling and dies. Turn the key it cranks but wont start. Keep doing this til battery starts to give out. Put it back on the charger and even tho I have just under 1/4 tank I add some more gas. Just cranks but wont come to life. Hooked up my Diablosport Predator and no codes. I even went back to stock tune and nothing. Any ideas??

 

[wmburns]

Replace weak/dead battery.

Get a new battery. Today's cars simply will not run correctly without a STRONG battery and charging system. The cars computer (PCM) will not work without the correct voltage.

Further, the alternator can not work without a battery to excite the field coil. The days of jumping a car with a dead battery are OVER. A classis symptom is car will jump OK, idle for a while. Maybe even drive for a while. But just as soon as there is a load increase, the car will die.

Check all of your battery terminals ensure they are CLEAN and tight. Check your fuses to be sure one hasn't blown while running on reduced voltage.

Also, bad idea to reprogram a PCM when the battery is weak. Taking a chance on a voltage induced failure upsetting the actual re-progamming.

 

[trailblazr81]

Has it been that long since Ive bought a car battery?? $100 locally.

 

[scupking]

Will it start if you hold your foot on the gas a little? If so its your IAC. You still might want to check your IAC.

 

[joshjwc9]

Yup, for a period of probably 2 months my Mustang had a condition of weak starts (taking several cranks, then having to rev it up to make it keep idle. I pretty much knew it was a combo of an old battery and original IAC with 125k on it. So I replace the battery and it starts cranking right up every morning. Then about a week later it doesn't even start. So I clean the IAC and it starts twice before it just keeps cranking.

Run to Autozone and grab a IAC, install it, and it starts like it should have right off the assembly line. 6 months later and it still does.

 

[trailblazr81]

Well I replaced the battery and still it just cranks. Tried cracking throttle, nothing. Wiped out IAC, still nothing. In this picture isnt this a purge for the fuel? I pushed it in and nothing came out. Good, bad, or indifferent?
View attachment 222672

 

[wmburns]

Sounds like you have zero fuel pressure.

What is the theft light doing? If flashing, PATS has been activated. PATS will disable the fuel system. Crank with no-start would be expected.

Check the IFS switch in the trunk.

Check all of your fuses in both fuse boxes.

Otherwise, sounds like a bad fuel pump.

 

[trailblazr81]

OK this is odd. I tried the IFS switch and nothing. I dig out my old spare key, try it, and it roars to life!! But like before I give it gas and it stumbles then dies. And now again cranks but wont start. crapolaamnit:

 

[wmburns]

Try cycling the key on/off several times without starting. Do you hear the fuel pump run? Does this improve the starting?

You did not answer the question about the theft light. For PATS to have been the reason for no start, one would have expected the theft light to flash.

Maybe handy to know what is the fuel pressure since it is looking like a bad fuel pump.

 

[trailblazr81]

Well it seems that since I got the car used from a dealership the theft light has flashed. Thought it was from me not wanting to pay $500 for a "theft deterent system". Or it could have been since I had a 2nd key made which was a matter of days after I got the car years ago. I never had a problem with it so I just ignored it. Also how do I check the pressure?

 

[wmburns]

The theft light always slow flashes to indicate the system is working. Normally the theft light goes out when the key is turned to on after a 3 second prove out.

Put the key in ignition. Turn to run (do not start). Does the theft light go out after 3 seconds. If not, PATS is preventing your car from starting. Count the blinks and post.

If PATS has not been activated, diagnose as a zero fuel pressure problem. Start by checking all fuses. If gas doesn't squirt out of the test port, the pressure is too low.

Also try starter fluid.

 

[trailblazr81]

Turn the key to ON and "THEFT" light goes out immediately. Tomorrow I will check all fuses and relays.

I really dont want to have to change the fuel pump.

 

[trailblazr81]

All fuses look good.