Engine will not shut off

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Apr 15, 2017 | 12:12 AM

amforeman

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Engine will not shut off

I am working on a 2007 F350 ambulance for a volunteer fire department. It run great, even with the key turned off sometimes. This is an intermittent problem. About every 10 times it is used the engine will not shut off when you turn the key off. The instrument cluster turns on and off as normal. The other odd part is if you leave the key in the off position when the engine does not turn off the RPM starts going up. I have not left it in off long enough to see how high it would go. It does not have a remote start and never has. Anyone have any ideas.

Apr 15, 2017 | 01:55 AM

163junk

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From: Western NY

Is it a volly rig? Most of them had a module added to idle with the keys removed . Usually has a button to push when you shut it off hold and remove the key step on brake it would stall

Apr 15, 2017 | 07:15 AM

amforeman

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Volly rig

I have never heard of a volley rig. If we can get it to fail I will try stepping on the brake. Thanks.

May 5, 2017 | 11:20 PM

amforeman

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Hopefully repaired

According to the ambulance manufacturer it did not have anything added that would make it run with the key off. It was taken to a Ford dealer who replaced the PCM relay and the ignition switch. Only time will tell if it is going to not shut off again.

May 6, 2017 | 10:24 AM

53jimc

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From: Roebuck, SC

Hope it's not a symptom of a turbo oil seal leak where the engine is running on it's own oil. That can be disastrous if the leak is big enough.
They make a shut off valve for the 6.0 in case it happens, but it's 600+
BD Positive Air Shutdown(PAS) Ford PowerStroke
Here's a video of a runaway:

May 23, 2017 | 08:32 AM

amforeman

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Problem came back

The ignition switch and PCM relay did not fix the problem. I contacted the ambulance manufacturer and got information on the electrical interface. One of the connections was called ignition. I waited until it would not shut off and disconnected the wire and it shut off. Not sure why it just does it sometimes. I added a relay to isolate the feedback and everything seems to be working.