Hard starting at initial startup.

[blaisa]

I have a 17 GT. Just got the car (non-running initially). It is really hard to get started for the first time of the day. After that it starts right up with no hesitation. Cranking time off and on to get it started in usually about 15 to 20 seconds. The only thing that seems to help is to put The only code it has is intake air temperature sensor high resistance. I know it is not the sensor because I swapped the sensor out for a known good one from my other 17 GT. I have inspected the iat sensor wiring and it looks good.

Any suggestions would be greatly appreciated

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[blaisa]

The only thing that seems to help is putting the gas pedal to the floor.

 

[ORRadtech]

Check the fuel pressure before, duringand after start up. Also look for a check valve or anti siphon valve in the fuel line.

 

[KingKona]

Battery.

 

[bullittt]

Check the fuel pressure before, duringand after start up. Also look for a check valve or anti siphon valve in the fuel line.

I would start with this. After that initial run, the fuel system is primed. If you don't have an easy way to check the pressure, take the airbox hose off (when cold), have someone press the gas (ie, open the throttle body) and shoot a little starting fluid in there. If it fires immediately, it's a fuel problem.

Sonny

 

[blaisa]

Battery.

The battery is brand new and cranks the engine over very fast.

 

[blaisa]

Check the fuel pressure before, duringand after start up. Also look for a check valve or anti siphon valve in the fuel line.

Where is this check valve you mentioned?

 

[JetGray_Mach1]

What is the mileage? Spark plugs could cause long startup. Good luck.

Also, do you get any smoke at startup? any oil consumption issues?

 

[Dapsters]

My truck has this exact issue but.. it's a very different system since it's a 95 f150 with a 5.0

The cause in my truck is the evap solenoid is commanded open from the start and drowns out the motor with fumes. Something messed up in the circuit as the valve tests fine, truck runs great if I block it off but the second I hook it back up it dies and just cranks until I floor it then it'll sputter and die. If I run it long enough it'll have no issues the rest of the day until the next morning

Probably no use to you but I find it interesting

 

[K4fxd]

Where is this check valve you mentioned?

It's built into the fuel pump.

 

[WildHorse]

The only thing that seems to help is putting the gas pedal to the floor.

Usually means it's flooded.

 

[ORRadtech]

It's built into the fuel pump.

Don't these cars have 2 fuel pumps? Mine's an EB but I'm pretty sure it has one in the tank and a high pressure one on the back of the engine. Is the 5.0 the same?

 

[K4fxd]

Don't these cars have 2 fuel pumps?

The gen 3 coyotes, 18 and newer, have a high pressure pump for the DI system.

 

[sk47]

Hello; Fuel injection systems tend to have a fuel rail from which the injectors are feed fed fuel. To work properly the injectors, need some amount of pressurized fuel. The fuel pump(s) are made to produce more fuel pressure than the injectors actually need. So, if the injectors need 60psi and the pump makes 80psi some of that pressure needs to be bleed off.
On the fuel rail will usually be a pressure relief valve which can open to bleed off some excess fuel pressure. That excess fuel is sent back to the gas tank to be held and eventually reused. If that valve is faulty it can fail to hold pressure when the engine is turned off. It may allow fuel pressure to slowly bleed off over time (say overnight). When you start the engine for the first-time next morning it takes some longer cranking to get enough fuel pressure built up. Then the rest of the day you may be starting it often enough to keep the fuel pressure up.

Another way pressure can bleed off is a faulty injector.

 

[Cory S]

The only thing that seems to help is putting the gas pedal to the floor.

This stops the fuel injectors from injecting fuel during cranking. You may be getting too much fuel during prime/cold start.

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