Not Wanting to Start When Hot

[Lzr96Snake]

I just drove my Cobra to the Somernites Cruise last weekend. On Friday I drove approx 150 miles and shut it off at a gas station in Bowling Green. It sat for about 10 min. When I went to start the car, it cranked over but wouldn't start. I cranked on it for 5-10 seconds before it started cranking faster and faster until it started. Drove it to Somerset (another 100+ miles) shut it off at the hotel. After checking in it started right up. Drove it around all weekend and it never acted up again. Sunday I drove it home, stopped for gas again in BG, and it started right up with no issue. Got home, unloaded the car and went to start it. Wouldn't start. I cranked on it for another 5-10 seconds, then cranked on it again. I let it sit for about 10 minutes and tried again. Still wouldn't start. Finnally as I was cranking on it, I pressed the accelerator, and it immediately started cranking faster and faster till it started. After it starts up it runs and idles normal. No check engine light. I do hear the fuel pump prime when I turn the key on. Anyone have an idea what's going on? All of my mods are in my sig, and was installed in April of last year. I will say it was really hot out. (95+ deg) Heat advisory all weekend, and I run the a/c the whole way there and back. I'm wanting to drive it to a couple more shows this year that are around 200 miles away and don't want to get stranded. Any help would be appreciated.

 

[Lzr96Snake]

Anyone?

 

[MustangMatt77]

I'm thinking fuel pressure related.
How old is the filter? Do you have a fuel pressure tester?
Check the regulator as well.

 

[Lzr96Snake]

I'm thinking fuel pressure related.
How old is the filter? Do you have a fuel pressure tester?
Check the regulator as well.

I replaced the fuel filter over the winter. (Approx 1k miles)
No, I don't have a pressure tester. I have a inline fuel pressure gauge that I've never installed. I'm going to install it in a few days. As far as I know it's the original fp regulator.

 

[iamtheshaner]

If opening the throttle helps it start, its getting flooded. Possible leaking fuel injector or pressure regulator. Not sure exactly what you mean about it cranking fast but a flooded motor will crank a tad fast. See how consistent it wants to start with the throttle open

 

[Lzr96Snake]

If opening the throttle helps it start, its getting flooded. Possible leaking fuel injector or pressure regulator. Not sure exactly what you mean about it cranking fast but a flooded motor will crank a tad fast. See how consistent it wants to start with the throttle open

Ok thanks. How can I diagnose if it's an injector leaking down or a fp regulator issue?

 

[MustangMatt77]

Watch this, gives you an idea on how to check a fp reg.
http://m.youtube.com/watch?v=AKtR_yF7bi8

As far as a fuel inj. Goes, you can check the resistance, but beyond that I'm not sure.

 

[Lzr96Snake]

Thanks for the video. Think I'll try a regulator first since I think it's the original one.

 

[iamtheshaner]

If you suspect a leaking injector, remove plugs and crank engine with ignition module disconnected. Cylinder spitting fuel is your culprit. I would really only do this if I was sure my fuel pressure was bleeding off

 

[encasedmetal]

it's called a hot start. if pressing the gas pedal all the way to the floor makes it start, then your tune needs to be adjusted for hot start. your crank fuel pulsewidth uses ECT temps to adjust injector PW, and your ISC duty cycle plays a part as well. BTW- you aren't flooding the motor- you're just getting too much fuel for the motor to start. so if for instance you waited and then it cranked without you pressing the gas pedal- it's because the ECT temps came down and the injector pulsewidth hit the right range, not because fuel evaporated out. these aren't carbed motors

 

[iamtheshaner]

it's called a hot start. if pressing the gas pedal all the way to the floor makes it start, then your tune needs to be adjusted for hot start. your crank fuel pulsewidth uses ECT temps to adjust injector PW, and your ISC duty cycle plays a part as well. BTW- you aren't flooding the motor- you're just getting too much fuel for the motor to start. so if for instance you waited and then it cranked without you pressing the gas pedal- it's because the ECT temps came down and the injector pulsewidth hit the right range, not because fuel evaporated out. these aren't carbed motors

This is all true but how did his tune just forget hot start perameters?

Maybe he has an ECT issue and it isn't setting codes because the thermostat monitor has been disabled? Either way I was providing advice based on the fact that the issue just popped up

 

[Lzr96Snake]

Thanks guys. When I had it tuned last year, I asked for a conservative tune. Well, I got what I asked for, cause it's been running rich. Every time I get on it it blows black smoke. Worse when it's cold. I've been wanting to take it back up there and have him retune it to lean it out some. When i do, I'll ask him to check what it's set at for a hot start. I still think I'll replace the regulator first. Sucks I have to pull the blower to do it.

 

[ImThatGuy]

This is exactly true. My 96 Cobra does it very rarely. I believe its in the tune as well, as it never done it before the tune. I would have yor car retuned!

 

[encasedmetal]

This is all true but how did his tune just forget hot start perameters?

Maybe he has an ECT issue and it isn't setting codes because the thermostat monitor has been disabled? Either way I was providing advice based on the fact that the issue just popped up

could be possible his tuner didn't set his hot start parameters to begin with. not trying to argue, just trying to help the OP. btw- I've never heard of a thermostat monitor- what is that?

 

[iamtheshaner]

could be possible his tuner didn't set his hot start parameters to begin with. not trying to argue, just trying to help the OP. btw- I've never heard of a thermostat monitor- what is that?

Cool, not trying to be argumentative either. Thermostat monitor watches how quickly the coolant or cylinder head temp reaches around 190* (it varies model to model). If the tstat sticks open, a P0125 is set which says something to the effect of "insufficient coolant temp for closed loop control". I've been a Ford driveability tech for years but I'm just starting to learn EFI programming so I just assume this tstat monitor would be a common thing a tuner would "turn off" in addition to SAI, catalyst monitor, EVAP monitor, etc.

 

[encasedmetal]

Cool, not trying to be argumentative either. Thermostat monitor watches how quickly the coolant or cylinder head temp reaches around 190* (it varies model to model). If the tstat sticks open, a P0125 is set which says something to the effect of "insufficient coolant temp for closed loop control". I've been a Ford driveability tech for years but I'm just starting to learn EFI programming so I just assume this tstat monitor would be a common thing a tuner would "turn off" in addition to SAI, catalyst monitor, EVAP monitor, etc.

ah I understand now. there's nothing in the software related to the thermostat itself- it's all based on coolant temp sensors. so whatever they read effects open/closed loop, fan settings, timing etc.

 

[DSG2NV03]

Encasedmetal has it. Not bagging tuners, but to get a car 100% dialed in needs all temperature starts, cold starts and such that you just don't get on a few hour dyno flog. I would say it is in the tune also. Perfect drivability takes a long time. Tables for different ECT change startup parameters to add and subtract fuel. Seems you have too much fuel at the temp band, and flooring the throttle turns off injectors to allow it to catch up.