6.0L Fuel pump?

[Matthew Jeschke]

I am digging into the Crank and Cam position sensors. Seems there's not many PID's in HP tuners for my Gen III setup. I have the older style sensors (not on timing cover and fewer teeth).

I can log a Crank Position Voltage signal, unfortunately not frequency. I can recreate the pulses from the cam sensor, and log the crank misses / missed teeth in counting.

It's a theory, I'll likely confirm in this. I built the 6.0L and this problem has been ever since I built that engine. Again, it will start cold no problem... Get to operating temp and start again no problem. It's only if it sits for 15 minutes or so at operating temp then I try to restart it again. I wonder if, the crank sensor is moving as the block cools a bit and missing some teeth.

I REALLY wish I could just see the waveform for the sensor instead of the current. Would be nice to have a Tech 2 at this point.

UPDATE: I recreated the hard crank problem. I logged crank position (current), crank missed counts, and cam position while cranking the motor. Something interesting... Crank position had no anomalies. However, I noticed I wasn't getting all the cam position pulses while cranking. Once engine fired it appeared to be getting them (sometimes with missing pulses / gaps)... I wonder if the ECU can make do with crank sensor data even if the cam position sensor is acting up a bit.

I suspect it the cam position sensor is bad... Anybody have the ohms reading for the cam position sensor 2001 (older style back of block)?

 

[Donal]

I am digging into the Crank and Cam position sensors. Seems there's not many PID's in HP tuners for my Gen III setup. I have the older style sensors (not on timing cover and fewer teeth).

I can log a Crank Position Voltage signal, unfortunately not frequency. I can recreate the pulses from the cam sensor, and log the crank misses / missed teeth in counting.

It's a theory, I'll likely confirm in this. I built the 6.0L and this problem has been ever since I built that engine. Again, it will start cold no problem... Get to operating temp and start again no problem. It's only if it sits for 15 minutes or so at operating temp then I try to restart it again. I wonder if, the crank sensor is moving as the block cools a bit and missing some teeth.

I REALLY wish I could just see the waveform for the sensor instead of the current. Would be nice to have a Tech 2 at this point.

UPDATE: I recreated the hard crank problem. I logged crank position (current), crank missed counts, and cam position while cranking the motor. Something interesting... Crank position had no anomalies. However, I noticed I wasn't getting all the cam position pulses while cranking. Once engine fired it appeared to be getting them (sometimes with missing pulses / gaps)... I wonder if the ECU can make do with crank sensor data even if the cam position sensor is acting up a bit.

I suspect it the cam position sensor is bad... Anybody have the ohms reading for the cam position sensor 2001 (older style back of block)?

No but wish that I did. I will send a message, though,

 

[rockola1971]

I am digging into the Crank and Cam position sensors. Seems there's not many PID's in HP tuners for my Gen III setup. I have the older style sensors (not on timing cover and fewer teeth).

I can log a Crank Position Voltage signal, unfortunately not frequency. I can recreate the pulses from the cam sensor, and log the crank misses / missed teeth in counting.

It's a theory, I'll likely confirm in this. I built the 6.0L and this problem has been ever since I built that engine. Again, it will start cold no problem... Get to operating temp and start again no problem. It's only if it sits for 15 minutes or so at operating temp then I try to restart it again. I wonder if, the crank sensor is moving as the block cools a bit and missing some teeth.

I REALLY wish I could just see the waveform for the sensor instead of the current. Would be nice to have a Tech 2 at this point.

UPDATE: I recreated the hard crank problem. I logged crank position (current), crank missed counts, and cam position while cranking the motor. Something interesting... Crank position had no anomalies. However, I noticed I wasn't getting all the cam position pulses while cranking. Once engine fired it appeared to be getting them (sometimes with missing pulses / gaps)... I wonder if the ECU can make do with crank sensor data even if the cam position sensor is acting up a bit.

I suspect it the cam position sensor is bad... Anybody have the ohms reading for the cam position sensor 2001 (older style back of block)?

With those cam and crank sensors its just not a good test to do simple resistance readings because of the type of sensor they are. They actually do something instead of a simple variable resistance change like what would be found on a coolant temp sensor. The cam and crank sensors actually make pulses based on when and how many metal targets pass the center of their faces. This symptom of yours is a stereotypical "failure" of a cam or crank sensor. They can fail totally and the engine just plain wont start or they work most of the time like what you are seeing and then fall on their face as they get heat soaked by that huge heat sink they are mounted to which we call an engine block. At this point and for how long you've been fighting it and its been original to the engine install I would fire the parts cannon and install a new camshaft position sensor on it. They are cheap enough and easy enough to change out. Have a look at the face of yours when you remove it and see if something (metallic) has collided with it.

 

[Matthew Jeschke]

Ah, gotchya, is it a HAL effect sensor? I was trying to find that info, mainly for trivia purposes. Not as familiar with reluctance which I see is another type of sensor. I used to design this stuff as an engineer Bit rusty now though...

I'll just throw a new cam position sensor in. I cannot see anything wrong with the crank, as it's not missing count of any of the teeth during the hard startup.

 

[rockola1971]

Ah, gotchya, is it a HAL effect sensor? I was trying to find that info, mainly for trivia purposes. Not as familiar with reluctance which I see is another type of sensor. I used to design this stuff as an engineer Bit rusty now though...

I'll just throw a new cam position sensor in. I cannot see anything wrong with the crank, as it's not missing count of any of the teeth during the hard startup.

Its been awhile since ive had to mess with one but it will be either a hall effect or magnetic pickup type. The Hall effects will have 3 wires. 12v, gnd and sensor output. Hall effect willl have a square wave output and the magnetic type will have a sawtooth wave.

 

[mattbta]

Is the cam sensor OEM? Shop put an off-brand one in mine and it was randomly crank no start like the vid below. I suspected it since there have been so many reports of problems with non OEM, but fired a parts cannon of FPR & fuel pump before putting an OEM cam sensor back in. Once I did the OEM sensor, it starts first time, every time.

 

[Matthew Jeschke]

I have the original cam sensor from the factory. I pulled it out of my 5.3L and used it in my 6.0L build when I scrapped the old motor.

Thanks for letting me know about generic cam sensors. I was curious if it's worth saving a few dollars to get one, now I know. Actually, it's more about I can get generic in town here and have to order OEM by mail, will take a few more days to fix.

Per your video, THAT'S MY EXACT SYMTOM. Only detail is, it only does it once a engine has sat turned off for a few minutes at operating temperature.

 

[Fless]

If it hasn't been done, it's recommended that a cam-crank correlation procedure with a scan tool be done any time either sensor is changed.

 

[mattbta]

Mine started out that way - that video was taken 20 minutes post shutoff. Then it progressed to also doing it when sitting overnight. There didn't seem to be a pattern. 3 out of 5 would start immediately.

But yeah, your's might be bad since it's original.

BTW, i regularly buy off partscenterplus on ebay, which is an Autonation Chevy out of Gilbert. Good prices.

 

[Matthew Jeschke]

If it hasn't been done, it's recommended that a cam-crank correlation procedure with a scan tool be done any time either sensor is changed.

@Donal was kind enough to PM me the procedure

Mine started out that way - that video was taken 20 minutes post shutoff. Then it progressed to also doing it when sitting overnight. There didn't seem to be a pattern. 3 out of 5 would start immediately.

But yeah, your's might be bad since it's original.

BTW, i regularly buy off partscenterplus on ebay, which is an Autonation Chevy out of Gilbert. Good prices.

Thanks! I'll save them as a preferred seller.