CAR WONT START WHEN HOT.. I've gone through the checklist already and did searches..

Ny Mustang Guy

Founding Member
Dec 10, 2001
322
0
0
Queens Nyc
I've went through the checklist over and over.. I've done Threadsearches.. and I cannot find the problem! I HAVE A '90 5.0 IN MY RIDE

She will not start when hot.. sometimes she does.. sometimes she doesn't.. it is kinda a toss up.. but it is always when I've been driving a while and she is hot. I shut the car off.. go to turn her back on and she just turns over and over and over.. I have Fuel pressure, Starter is good, I have good spark, changed the TFI Module, timing is not off, fuel pump primes, no vaccuum leaks, I have a good ground..... I have to wait about 40min before I can start her up again.. She runs beautiful other than that. ANY SUGGESTIONS!?..:shrug:

Recent Upgrades Before the Problem (255lph Pump, Upper/Lower Intake, Fuel pressure regulator, Longtube headers)
 
  • Sponsors (?)


the only part of the Checklist that i am unsure about is E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.

-Engine coolant temperature sensor??

If I press the throttle to the floor.. eh.. she will start but it takes the same amount of time as if i wasnt pressing the gas...
 
my explorer did the SAME-THING I checked everything then one day it would not start and i took off the air intake hose to the upper and sprayed starting fluid in it and it started ,so i replaced the fuel pump and fixed it
 
Can you give a little more info. How it sounds when it starts? Does it sound like a dead battery? Does it even crank? Does it just turn over fine but never starts......?


Need more info.


Fred
 
when you press the gas to the floor like that it cuts the injectors so it only gets air until it passes a certain rpm i believe. Not sure if that helps you, but the ECT sensor adjusts mixture by reading the coolant temp maybe replace that its only about 15 bucks.
 
Check all your grounds...especially the neg battery cable to the block. I had the same problem with my car two summers ago and i could never get it to start when i was up to temp. raplaced the cable and added a second ground and vuoalah! I have also heard that the ECT can cause some problems, so u might just want to replace it...its like 16 bucks.
 
where is the ECT Sensor located?.. This is the first time I've heard of this name.. Maybe I know it by a different name? The car does not sound like a dead battery (I also hooked up a booster pack on it to make sure it wasn't a battery problem).. just turns and turns and turns.. I replaced the negative wire to the battery yesterday. I am going to drive it today to see if there is any difference.

It also seems like its random when it happens.. like I'm afraid to shut the car off when I've been driving a while because It may not turn back on..lol.. I drove it yesterday no probs.. but 3days before that in a row it would do it atleast twice on me

That is a new 255lph pump in there also. Really sucks that I have this dumb prob.. I will look into the ECT Sensor.. She runs BEAUTIFUL.. just that stupid problem!.

Thanks
 
The ECT lives in the heater tube plumbing on the passenger side. It is the only sensor in the heater tube and is located right in the area where the heater tube connects to the lower manifold.
 
Off the top of my head, I would look at the distributor pickup coil, I don't think it is part of the TFI module. I have had several of these fail on Durasparks. Next up would be the ignition coil.

If thats not it, try getting codes when you have the prob.

Something is unhappy when hot.
 
If you have good spark than your problem is defanently fuel.
With your list of recent mods along with the problem of only hot starting I would say you're just getting too much fuel. An 'engine is cold' signal from the ECT to the computer will most certainly cause this. However, if this is your problem, after cranking it for a few seconds, if you put the pedal to the floor and crank it should fire right up. If not, there might be more going on. Or your WOT injector cut-off at startup isn't working.
 
i changed out the coil 2 days ago and got stuck yesterday again.. for a/b 20 min.. so it's not the coil.. i did smell gas when i was trying to start it.. maybe it's dumping gas?.. but why is this random.. it doesnt happen when I first get hot.. what I've noticed is when it happens ive been driving a while and i've turned the car on and off atleast 3..4 times. and it happens probably a cpl hours after I 1st started the car if I've been driving on and off throughout the day. I've also noticed that I can most likely tell when its going to happen.. b/c the starts get more and more harder (like 1st start is quick. 2nd start is okay.. 3rd start is a couple turns til it starts.. and maybe 2 or so more times it just takes longer to start it until the car doesnt start, it just turns and turns and turns... then I have to wait atleast 10-20 min.. sometimes longer.. and it will start up again :bang: :bang: )

I changed out the ECT sensor last night.. I'll see if that did the trick today. I'll keep the *crank it a cpl seconds and then Press the pedal down all the way and see if it starts* comment in mind... I've tried every other way.. after I get stuck and wait.. she starts right up and runs beautifully:shrug: she does idle a little high (1100-1200rpms) when this happens.. but she always goes bak down to 900..
 
There is only ONE thing I can think of.. The wire that connects to the Fuel pump.. the clip that goes to it disintigrated so I had to break it apart and use the 2 lines and connect them to the 2 poles on the pump and put some of that black putty substance to hold them in.. could that be a prob?.. the pump ALWAYS primes when I go to start the car though. Where can I find this fuel pump connector?... MAYBE it can be something to do with that when it gets hot after a cpl starts? the pump primes EVERY time though
 
I didn't really read all the above posts but if your car dies when hot and wont start when hot. I had same problem as well as a lot of people, its most likely the Ignition Module on the side of the distributor. They go a lot on our mustangs
 
It's not the module when you have spark. Unless I'm mistaken when you have spark you have injectors. If you have 39 psi of fuel even when it's not starting your pump is working just fine.
I really think it's too much pulse width on the injectors. In other words, your computer is still in cold start choke 'lots-o-gas' mode even when the engine is warmed up, and you have too much fuel for the hot thin air.
I don't think it's the starter... from what I understand the motor is cranking but not catching.

When doing the wide open throttle thing. Crank it for a couple of seconds at closed throttle. This will put gas in the cylinders. Release the key, then open the throttle completely, and crank the engine again. It will blow the excess fuel into the exhaust but leave a small amount behind, that small amount should ignite on the second go around, it will almost want to catch. Right when that happens, release the gas pedal down to 10-20% which should turn the gas back on, and hopefully with the help of the first pop she'll catch.

It might be worthwhile to doublecheck your engine ground and engine to firewall groundstrap next time you're under the hood if you havn't already.
 
I had the same problem and it was the colant temperature sensor. Run the car until it warms up then if it doesn't start disconnect the colant temperature sensor and see if it starts then. That is what I did. It was not showing on the scanner when I was scanning for a code.