6.0 does not start when hot - Ford Powerstroke Diesel Forum
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  #1  
Old 09-16-2012, 01:16 PM
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6.0 does not start when hot

My 2006 F-350 diesel doesn't like to start when the engine is hot. The pressures have been checked and there seems to be no issues there. Cleaned the water seperator and the radiator. Haven't been able to get any conclusions to what the problem is.
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Old 09-16-2012, 02:32 PM
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What pressures were checked?
If I was a gambling man, I would say your problem is high pressure oil system related.
Likely suspects are:
The STC fitting that connects the HPOP (high pressure oil pump) to the high pressure oil system. This fitting is much like the same style fitting you would see on an air line in the garage. The internals wear out over time and the fitting will leak, causing the problem you describe.
Next would be the standpipes or the dummy plugs.
Short description of your high pressure oil system:
Oil from the small reservoir under your oil cooler feeds the HPOP.
The oil is pressurized by the HPOP, and that pressure is regulated by the IPR (injection pressure regulator).
The HPOP connects to the branch tubes via the STC (snap-to-connect) fitting. The branch tubes split the oil delivery in two (one for either side of the engine).
Standpipes deliver the oil from the branch tube up to the oil rails (sitting on top of the injectors). There are o-rings on the standpipes that can (and do) fail.
The oil rails are common to both sides of the engine. To make that possible, there are holes machined into the rails that are used when the rail is installed on one side of the engine, that are not used when installed on the other side. The dummy plugs plug these holes. These also have o-rings on them that also fail.
The ICP sensor is threaded in to the passenger side oil rail, and monitors the oil pressure present in the rail.
The PCM uses the information from the ICP sensor to control the IPR.

The good news is that the STC fitting has been redesigned (as a straight fitting), the standpipes and the dummy plugs have also been redesigned for longer service life.
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Old 09-16-2012, 04:49 PM
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X2 hpop leak.

Sent from my phone that somebody didn't help me get.
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Old 09-16-2012, 06:22 PM
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The high pressure oil system was checked and had good pressure. We replaced the ICP sensor and that didn't seem to do anything. When the truck is hot and try to start it it turns over but won't start. I have to wait a second then try again and sometimes that works the first time but sometimes it takes a couple trys.
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Old 09-16-2012, 06:27 PM
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What exactly was "good" psi on the hpop?

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Old 09-16-2012, 07:02 PM
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Quote:
Originally Posted by thomaslord84 View Post
What exactly was "good" psi on the hpop?

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Well...you need 500psi to start the truck. About 600psi at idle and up to 4000psi under full load.
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Old 09-16-2012, 07:11 PM
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Quote:
Originally Posted by mazsecond View Post
Well...you need 500psi to start the truck. About 600psi at idle and up to 4000psi under full load.
I know this I was asking the OP. Guess I should have made that clear. My bad.

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Old 09-17-2012, 06:11 AM
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The high pressure was over 500 and when the truckwas running he turned it down
to about 400 ??. then un hooked the Icp senser and said that it would
default to 900 high pessure. we thought maybe the ICP senser was giving
faulty information replaced no differance. This hard starting does not happen at every hot start but it is happening more often
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Old 09-17-2012, 06:41 AM
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What do you mean he turned it down to 400?

I just had my HPOP replaced about 3 months ago. Mine did the same thing as you are seeing when it first started. It progressively got worse, rather quickly, until it would not start at all over 125 ECT. With the new pump my psi is 600 - 650 at idle. I am putting my money on either a HPOP leak or a bad pump.

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Old 09-17-2012, 06:50 AM
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its got to be the high pressure oil system. just replace the standpipes dummy plugs and stc fitting to rule them out. they need to be replaced anyways.
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