6.0L Fuel pump?

[Matthew Jeschke]

New pump had no effect on underlying symptom. It starts great when cold, however, once up to temp and sat for 5 or 10 minutes doesn't want to start.

vapor lock

@BG1988 unfortunately, I missed your post initially. Just seeing it now after reviewing the entire thread. This makes since.

Others, say I have a leaky injector. They are all brand new, but maybe I need to put a pressure gauge on it and see how the pressure holds up. How else could vapor lock take place?

Additionally, I am getting notorious P0300 code from time to time.

 

[BG1988]

New pump had no effect on underlying symptom. It starts great when cold, however, once up to temp and sat for 5 or 10 minutes doesn't want to start.



@BG1988 unfortunately, I missed your post initially. Just seeing it now after reviewing the entire thread. This makes since.

Others, say I have a leaky injector. They are all brand new, but maybe I need to put a pressure gauge on it and see how the pressure holds up. How else could vapor lock take place?

Additionally, I am getting notorious P0300 code from time to time.

fuel expands when it gets hot if there is air in the line it can cause fuel to vaporize, another thing is the ignition coil(s) could be bad (bad batch installed) spark cables maybe even a faulty spark plug(s)

 

[Matthew Jeschke]

I have the original coils, 255,000 miles on them... How do you test that? Wouldn't coils act consistently at all temperatures?

 

[BG1988]

I have the original coils, 255,000 miles on them... How do you test that? Wouldn't coils act consistently at all temperatures?

an arc inside of it causing a misfire.... the only way to test is if you have a high level scan tool to see which are misfiring ..

 

[Matthew Jeschke]

I have HP tuners. I'll look to see if it has PID to log that. It's SO hard to catch it. Thanks!

 

[rockola1971]

I would first check voltages with real time scanner both before and during a hard start event. Check battery voltage and sensor voltages to see if they are low. Also look at crank and cam position data to see if it is missing or incorrect during no start condition. This smells like a bad crank or cam position sensor problem.

 

[Donal]

I have the original coils, 255,000 miles on them... How do you test that? Wouldn't coils act consistently at all temperatures?

The resistance increases as temperature increases. Low resistance when cold and high resistance when hot.

 

[Matthew Jeschke]

Awesome, those are making more sense to me. I can scan those pretty easy too.

 

[rockola1971]

The resistance increases as temperature increases. Low resistance when cold and high resistance when hot.

Using your theory a vehicle would never run once warmed up because the ignition most certainly increase in temperature sitting on top of a hot engine.

Thats not the fault in an ignition coil when it is failing intermittently. The fault is an electrical open (broken wire) which shows its ugly head once the coil is hot and the coil of wire within the ignition coil expands from the heat. Once cooled down then the fault goes away because the broken wire is now touching and the circuit is complete. This can go on for days or even months but eventually the coil fails permanently and becomes a permanent electrical open.

 

[Donal]

I did not say or imply that the coils would fail at any temperature. I said that electrical resistance increases as temperature increases. This means that the measured resistance at a given temperature of each of 8 coils can be recorded and compared to the resistance value of each coil at a 50 degrees increase in temperature will incidate a coil that has a resistance value deviation and may or may not be the cause of misfire. This is a bench test, not an operating test.

Your second paragraph describes the details of how the resistance increases to failure of function very well.