2016 RAM 1500 V6 FUEL TRADESMAN WONT START CORRECTLY WHEN SITTING IN THE SUN

[SKYLER POSTON]

Bear with me because this only happens in very specific circumstances.
My truck has had a long crank starting issue intermittently but now its a daily occurrence.
I leave for work at about 5 am and in Yuma, AZ right now its about low 60s. My truck starts perfectly and drives perfectly. I drive about 50 minutes at 65mph with maybe 3 stop lights between home and work. About 30 miles with turns and curves. I park my truck at 6 am and go out at 4:30 in the afternoon and it's now the low 80s. The truck takes a good 5 seconds to start. just cranking for 5 seconds. I drive home and park it over night and it starts just fine in the morning! Also if I drive it anywhere else after work, like to eat or movies etc. then drive home, it always starts fine. it just that one time sitting in the sun each day that it won't start correctly. Today I went out about 10 am and it started fine. I went back about noon and long start. I went back about 3:00 long start. I'm betting at 4:30...long start.

I've already cycled my ignition with 5-10 sec intervals on auxiliary to see if the lines are losing fuel due to a bad gate valve in the pump (thinking maybe the lines are draining back into the tank) but the hard start is still there.

I took it to the family mech and they couldn't replicate the issue in order to run a diagnostic on it. He did get a gas cap error code and cleared it and then said maybe the cpm need to be flashed by Dodge...?

No other mechanical issues other than cruise control not engaging sometimes but I'm pretty sure that's a connectivity issue in the column.

38xxx miles

 

[MADDOG]

If your mechanic got the gas cap code then no flash is needed but I bet a new gas cap is.

When it gets hotter and the fuel expands a bit, any pressure released by the system removes that pressure from the fuel system. So it takes a bit of time to build pressure in the system. Basically, any fuel held in your line retreated back towards the tank.

I'd start with replacing the gas cap.

 

[SKYLER POSTON]

If your mechanic got the gas cap code then no flash is needed but I bet a new gas cap is.

When it gets hotter and the fuel expands a bit, any pressure released by the system removes that pressure from the fuel system. So it takes a bit of time to build pressure in the system. Basically, any fuel held in your line retreated back towards the tank.

I'd start with replacing the gas cap.

Well he was saying it needed a flash because he thought it idled rough. I've never experienced that. He was surprised. The cap code never came back.

 

[Rampant]

I haven't had my hemi long enough to have issues [yet], but I have had this exact issue on two of my GM trucks. It was the fuel pressure regulator. I don't know if there is an equivalent setup on the hemi, but I will look it up on Alldata in a bit and let you know if it has any DIY diagnostics for that specific issue. Did your mech check fuel pressure?

Pressure in your tank has nothing to do with the fuel pressure in the system, that I know. The evap solenoid would dump excess tank pressure over atmospheric +10 psi. When I first read your post, I thought the check valve in the fuel pump was bad. In that case, it would bleed system pressure down when not running, but it would fire right up after cycling the key several times.

 

[Docpaulo]

Test your battery? Connections? Justa thought

 

[Rampant]

I just looked in Alldata, nothing specific to that issue. But, I did look up a couple sensors that could affect your situation. If you have a scan tool capable of capturing live data, look at all the temp sensors and make sure nothing is out of whack. For example, the Intake Temp Sensor could be way off and it would never throw a code, but would tell the PCM wrong info and the PCM could adjust the timing and injector pulse widths inaccurately as a result.

That may not be the issue, but not a bad place to start looking and easy to verify. You can check/monitor the coolant temp in your display.

Here is some info on the IAT that may possibly help:


Intake Air Temperature Sensor - Operation

OPERATION

The IAT sensor provides an input voltage to the Powertrain Control Module (PCM) indicating the density of the air entering the intake manifold based upon intake manifold temperature. At key-on, a 5-volt power circuit is supplied to the sensor from the PCM. The sensor is grounded at the PCM through a low-noise, sensor-return circuit.

The PCM uses this input to calculate the following:

- Injector pulse-width

- Adjustment of spark timing (to help prevent spark knock with high intake manifold air-charge temperatures)

The resistance values of the IAT sensor is the same as for the Engine Coolant Temperature (ECT) sensor.

 

[SKYLER POSTON]

I haven't had my hemi long enough to have issues [yet], but I have had this exact issue on two of my GM trucks. It was the fuel pressure regulator. I don't know if there is an equivalent setup on the hemi, but I will look it up on Alldata in a bit and let you know if it has any DIY diagnostics for that specific issue. Did your mech check fuel pressure?

Pressure in your tank has nothing to do with the fuel pressure in the system, that I know. The evap solenoid would dump excess tank pressure over atmospheric +10 psi. When I first read your post, I thought the check valve in the fuel pump was bad. In that case, it would bleed system pressure down when not running, but it would fire right up after cycling the key several times.

He hasn't tested for fuel pressure regulator yet because he wants to replicate the problem and diagnose it to save from throwing darts. I thought the check valve too so that's how I tested it but alas...

 

[SKYLER POSTON]

Test your battery? Connections? Justa thought

I'v thought that too but battery seems current (ba dun tss) and clean and good

 

[SKYLER POSTON]

I just looked in Alldata, nothing specific to that issue. But, I did look up a couple sensors that could affect your situation. If you have a scan tool capable of capturing live data, look at all the temp sensors and make sure nothing is out of whack. For example, the Intake Temp Sensor could be way off and it would never throw a code, but would tell the PCM wrong info and the PCM could adjust the timing and injector pulse widths inaccurately as a result.

That may not be the issue, but not a bad place to start looking and easy to verify. You can check/monitor the coolant temp in your display.

Here is some info on the IAT that may possibly help:


Intake Air Temperature Sensor - Operation

OPERATION

The IAT sensor provides an input voltage to the Powertrain Control Module (PCM) indicating the density of the air entering the intake manifold based upon intake manifold temperature. At key-on, a 5-volt power circuit is supplied to the sensor from the PCM. The sensor is grounded at the PCM through a low-noise, sensor-return circuit.

The PCM uses this input to calculate the following:

- Injector pulse-width

- Adjustment of spark timing (to help prevent spark knock with high intake manifold air-charge temperatures)

The resistance values of the IAT sensor is the same as for the Engine Coolant Temperature (ECT) sensor.

I have also considered the intake sensor because ambient temperature seems to be the biggest effector, but we haven't checked it yet. I'll make sure he does

 

[SKYLER POSTON]

So I just happened to check my air filter and the thing was nasty. Black. Full of whole bugs. I've never had a filter look like this one before. I'm shocked that all the times I've had it serviced no one mentioned it... I cleaned it out. Maybe that's a contributing factor.

 

[crackerjack1957]

You need a new filter.