Car hard to start when hot, how to fix it?

['13_ImpactBlue_GT]

Has anyone attempted to solve the problem that some 99-04 GT's have when trying to restart the car when the motor is hot?

(Edit) I have done the trick of turning the switch to start without cranking it until the odometer lights up.

 

[streethorse]

that is the first sign of a weak battery, is it stiil the factory issue?
Just my guess. And what about your spark plugs, I tried some Boush plugs a while back and
after about 10k the car became slow to start, changed back to motorcraft and it starts instantly.

 

['13_ImpactBlue_GT]

Factory plugs as far as I know.
Dont know about the battery.

 

[streethorse]

If its Motorcraft its the original, Try hooking up some jump cables
let it charge for a couple of minutes before trying to start and see what happens.

 

[PULMEOVR]

It's not battery related. Mine always had the hot-start problem, and even after changing over to a fresh battery last month, the problem still exists.

 

[ran260gt]

On My Mustang, it seems to do it after a short drive on really hot days , but not all the time!

Its just something about the Modular engines , my mustang has been doing it as long as I have owned it , early 05 !

I guess deal with it , It always starts on the second try

 

['13_ImpactBlue_GT]

I guess so.

 

[Flghtmstr1]

Mine has always done it. It's just one of the "quirks" of the 2v engine.

 

[GT Tommy]

Hard Startig when hot?

I'm wondering if it is a fuel related problem. I notice that some cars will start up better if you turn your ignition switch to the on position for a couple seconds first, then to the start or run position. What this does is allows your fuel pump to energize and build up the required fuel pressure in the fuel line to start the engine. Some fuel systems will retain the fuel pressure in the fuel line much longer than others after the engine is turned off. When the engine is hot, I would think that it would lose fuel pressure more rapidly through evaporation than it would when it is cold. I would say for those of you who are experiencing these same symptoms, get the fuel pressure test gauge kit that Ford sells, and check you fuel pressure at your fuel rail when the engine is cold, and when is hot, to see what the difference in pressure is. Not sure what the values are, however, after your engine is turned off from running, it is suppose to hold a specified amount of fuel pressure for a given amount of time. If your fuel pressure in the line drops down too quickly, that would indicate a problem in the system. I will do some checking to see what the values are and post it here if I find something. If someone already knows what those values are, perhaps they can also post it here. For those who are experiencing these same symtoms, perhaps you would try turning your ignition switch to the on position for a couple of seconds first, then try starting your engine after that. If your engine starts up right away, then you know that your problem is fuel related. Let us know what your results are. Thank you and good luck, Tommy.

 

[GT Tommy]

Hard Startig when hot?

Here's what I found concerning the Fuel Pressure Leak Down Values. For EXAMPLE: If you had a fuel pressure gauge installed on your fuel rail, and you start your engine and you note that the fuel pressure reading at idle is a steady 40 psi, which is normal, that is good. However, when you turn off your engine, if you lose 5 psi of that 40 psi in one minute after you turned off your engine, that indicates a fuel pressure leak somewhere. Your fuel system cannot lose more than 5 psi of that 40 psi within one minute after you turn off your engine. If it does, that would indicate a leak somewhere in the system. The leak could be anywhere. Area's that come to mind right away, would be your Fuel Rail Pressure Sensor, your Fuel Pressure Regulator, or your Fuel Injectors could be leaking. So, for those who experience hard starting when your engine is hot or cold, this could be your problem. If you want to know for sure, you will have to purchase a fuel pressure gauge tester. To avoid running into installation problems, I would recommend getting the correct fuel pressure gauge kit made for Ford vehicles. The one shown below in the drawing is made for Ford vehicles. I would think it would be available from the Ford Parts Dept, not absolutely sure. Perhaps you already have one that will work for your Ford system. Good luck, Tommy.

View attachment 260454

 

[Pearl02]

I have one that works on Ford, Chevy and Dodge/Chrysler products. Will that work on the Satng if I needed it? I haven't had to use it on the Stang. I have used it on a friends Ford. Pearl02.

 

[GT Tommy]

Will it work for a Stang?

I have one that works on Ford, Chevy and Dodge/Chrysler products. Will that work on the Satng if I needed it? I haven't had to use it on the Stang. I have used it on a friends Ford. Pearl02.

I have no idea if the one that you have will work for the Mustang. Perhaps you should contact the store where you purchased it from and ask them. Does it have a brand name and part number on it? Let me know, I can check to find info on it, Tommy.

 

[Brute03]

i've had that prob for a while now, it's kinda embarassing at the gas station. FWIW my fuel pressure at idle bounces arond 32 psi and i think that might be a little low

 

[GT Tommy]

Fuel Pressure Value!

From what I read, the fuel pressure should be between 35 psi and 70 psi for a 2003 GT Mustang. I will recheck that value and re-post here. Good luck, Tommy.

 

[Flghtmstr1]

i've had that prob for a while now, it's kinda embarassing at the gas station. FWIW my fuel pressure at idle bounces arond 32 psi and i think that might be a little low

Mine is also 32 psi at idle.

 

[GT Tommy]

Fuel Pressure Chart!

Here are some Ford fuel pressure values from AllData. Click on the bar above the chart to enlarge it. Hope this helps!

 

[trinity_gt]

I think it's the calibration in the PCM. That 4-character code on your passenger door and on the PCM itself is what I'm talking about. Mine, an 02 GT, used to do this when basically stock (perhaps a few bolt ons...) with the factory MDE2 calibration. I had it dyno tuned and the shop used an MDE3 cal as the starting point. From that point on, I never had another hot-start issue. More recently, I had the Kenne Bell installed and when I filled in the card to send to KB for the tune, I indicated my car had the MDE2 calibration. They built the blower tune around that cal and guess what...the hot start issue is rearing its head again.

In my case, I don't think it's the fuel pump, the injectors, or any other fuel issue. I don't know what it is inside the cal but it certainly seems to follow the MDE2 tune.

 

[GT Tommy]

Hard Startig when hot?

Yes, we certainly can't rule out some type electrical problem as well. The cause could be a number of things. That's why it is so difficult to pin point. As mentioned in a previous thread, one quick way to check to see if the problem may be with the fuel system, is to try turning your ignition switch to the on position for approximately 2 seconds, then try starting your engine after that. If you find that your engine does indeed start up faster using this method, this may be an indication that your fuel system needs that extra time to build the required amount of fuel pressure in the system for the engine to start up right away. This could also mean that when you turn off your engine, your fuel pressure in your fuel line may be dropping faster than it should. Just something to think about. Good luck, Tommy.

 

[louredion]

It's not battery related. Mine always had the hot-start problem, and even after changing over to a fresh battery last month, the problem still exists.

 

[louredion]

i have a 98 mustang gt which was easy to start when cold but hard to start when engine hot, was happening for a couple years. Last month my car wouldn't start ..It cranks fine. So I changed my fuel pump and then it started but still had trouble starting when engine is hot. I replaced the purge flow sensor and purge solenoid. still wasn't fixed. then changed out the ignition coils, still not fixed. I finally changed out the camshaft position sensor. It fires up quick every time now. Just want to share my car issues with everyone. Hope this helps!!