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Discussion Starter #1
1999 E350 7.3 diesel, 147k miles, always garaged, hooked to double battery tender, and well maintained. A couple of years ago, I modded the fuel tank, installed an Air Dog, and upgraded the fuel pressure regulator in the Fuel Bowl. Fuel pressure was 67, dropped to 60 when pulling out or romping on it, but would quickly return to 67. Since May, I've had to be away and have returned home 3 times in the last 4 months; the van has been started 3 times. Last month, it was hard to start, slow long cranks and the fuel pressure was 58, which zeroed when pulling out or romping. Pressure is slow to recover, sometimes only to about 50. Called Air Dog Tech, and he recommended changing the fuel filters. I did that this time, but no improvement. Am I looking at an HPOP problem? What can anyone recommend for troubleshooting?
 

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I don’t see how it could be an HPOP problem. Could be the pump, regulator, sucking air, restriction in the pre-pump line or a bad sender. My oil pressure sender went out like this. I had already ordered new bearings before I swapped the sender. Pressure is back to where it was new...


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Discussion Starter #3
Thanks RT. Where is the sender located?
 

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Since the truck didn’t come with fuel pressure, it would have to be wherever you put it. Mine is screwed into the back of my fuel bowl. Some people use an isolation hose from the fuel bowl to a sending unit. Fass might have a mount on their filter housing..


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Yes, I installed the fuel pressure regulator in the fuel bowl housing. You mentioned an oil pressure sending unit causing your problems. I was referring to that.
 

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I was just using that as an example of how a sending unit can fail making you think you have a problem when you don’t.


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Discussion Starter #7
I misunderstood. I’m not sure where to even begin to troubleshoot. I may have to take it to the Ford garage.
 
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