Another no start 6.4

gorace · Jan 9, 2016

So I've been working on this thing for the past fuel weeks with no luck so figured I'd see if you guys can answer some of my questions.
I've got a no start condition, put the scanner on I've got over 7000 instantly, I've bleed the system, but my question is while I'm cranking the crank cam sync says NO. That being said I can get it to start if I jump the batteries with another truck, most of the time it starts almost instantly. I've had the batteries checked there about 2 months old, and it cranks fast like my other 08. When it does start the crank cam sync switches to YES.
Today when I tried again after batteries were charged over night, it cranked fast I tried starting for about 10 min rpm gauge would bounce, no sync, good pressure, I've got a new lpfp air dog 165, and I had my buddy hook up jumper cables I had him wait to hook up the positive on his truck, I started cranking no go and before I had finished cranking he hooked up the red and it started wtf!
What would cause the cam crank sync to say no while cranking?
Thanks ahead of time Christian

webb06 · Jan 9, 2016

I assume there aren't any codes that show up when you check? I've never heard of anything like this happening though

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Luke@MillerPerformance · Jan 9, 2016

gorace said:
So I've been working on this thing for the past fuel weeks with no luck so figured I'd see if you guys can answer some of my questions.
I've got a no start condition, put the scanner on I've got over 7000 instantly, I've bleed the system, but my question is while I'm cranking the crank cam sync says NO. That being said I can get it to start if I jump the batteries with another truck, most of the time it starts almost instantly. I've had the batteries checked there about 2 months old, and it cranks fast like my other 08. When it does start the crank cam sync switches to YES.
Today when I tried again after batteries were charged over night, it cranked fast I tried starting for about 10 min rpm gauge would bounce, no sync, good pressure, I've got a new lpfp air dog 165, and I had my buddy hook up jumper cables I had him wait to hook up the positive on his truck, I started cranking no go and before I had finished cranking he hooked up the red and it started wtf!
What would cause the cam crank sync to say no while cranking?
Thanks ahead of time Christian

The jumper cables are completing a circuit somehow. Check the power leads under the 10mm nuts on both positive cables.

gorace · Jan 9, 2016

What about the no sync cam crank? Should it say yes while cranking or only when it starts. What would cause that.Maybe it's just coincidence, that I put the cables on and it starts. It doesn't do it everytime. No codes ran the koeo tests too.

6.0 Tech · Jan 10, 2016

If you have a loose power lead going intos one of the junction boces as stated above, the pcm could be not getting the correct signals from the crank sensor. More than likely the light is not setting due to it being a crank sensor fault. It does not know the engine is cranknf so it doesnt yhink anything is wrong. I would also check the grounds by the accumulator/heater core inlet as those could have been left loose. There is also a ground right off the passenger side negative cable, and the body to frame ground under the body on the passenger side.

gorace · Jan 10, 2016

Should it say yes when cranking, or only after it starts.

6.0 Tech · Jan 10, 2016

Should say it while cranking. You should also be reading rpm while cranking. If it doesnt know its cranking, it wont try anything. If your cam sensor is bad it will still read rpm, butno sync. It will also not start because the engine wont know where #1 is.

gorace · Jan 11, 2016

OK going to get both sensors and install one at a time to see if I can get to say yes. When I crank it I do get the rpm bouncing but it never goes over a couple hundred rpm, even though I feel like it should be higher and it doesn't move all the time.

webb06 · Jan 11, 2016

gorace said:
OK going to get both sensors and install one at a time to see if I can get to say yes. When I crank it I do get the rpm bouncing but it never goes over a couple hundred rpm, even though I feel like it should be higher and it doesn't move all the time.

Cranking rpm is usually 150 but it shouldn't bounce. Usually jumps to 150 and stays there until it starts or you stop cranking

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6.0 Tech · Jan 11, 2016

:whs: i would start with the crank sensor first, as this seems to be the issue. How modified is your truck? I have seen 1 where the tone wheel got wore out or something and was flopping around giving goofy reasons.

Oh and on your sensors, i would highly recommend going with motorcraft...

gorace · Jan 14, 2016

Got both coming in motorcraft brand, and it cranks as fast as my other 6.4 new starter and batteries, but the gauge will bounce to about 200 then stop for a second then bounce again. I'll do the crank first, and see if sensor is scraped up maybe tthe ring came loose.

drunk on diesel · Jan 14, 2016

I've seen broken tone wheels on a couple 6.0's

Dalton_H · Jan 16, 2016

What kind of batteries? Had a truck a while back that would crank fine on the optimas in it but wouldn't start no matter if it was hooked up to a box or not. Threw another set of batteries in and truck would start everytime. Weird deal but if you haven't tried it yet, just swap the batteries with another truck and see if anything changes.

gorace · Jan 17, 2016

Yeah did that already, it had cheapo or OReilly batteries, 750ca, swapped auto zone 850 ca golds off a good running 08 and still same problem it think the one batteries are 750's. But I've got those sensors coming any day now.

gorace · Jan 17, 2016

Oem batteries are 750ca

gorace · Jan 21, 2016

OK got sensor in the mail, pulled the cranks sensor and it was cracked open on the tip. Put the new one in and it started right up after 2 weeks of not running thanks guys. I was not getting any ohm reading either from the old one the new one read .40