Intermittent fuel pressure fluctuation - PowerStrokeNation : Ford Powerstroke Diesel Forum
 
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post #1 of 5 (permalink) Old 03-20-2014, 07:27 AM Thread Starter
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Intermittent fuel pressure fluctuation

I just got a leak on the tranny temp sensor fixed and now this....seems like it never ends! lol Anyway, after I installed the gauge I had a good steady reading of 62PSI at idle and maybe down to 60 when accelerating gradually. Down to 51 at WOT. But cruising around at pretty much any speed was 61-62. Never wavered more than that. Starting this morning though it fluctuates at part throttle cruising only....and only intermittently. At idle, 62. Accelerating, around 60. WOT, around 51. When cruising along at 10MPH, 20MPH, 30MPH, whatever speed, it will sometimes read around 61 and other times will bounce rapidly between ~53 and 70PSI. For no reason whatsoever! If I drop off the throttle, it settles right back to a steady 62. If I get on the throttle, even just a smidge, it also settles out to around 60-61. Steady. After a minute or two of being steady while back at cruising it will begin bouncing like crazy again.

I did some searching and one possible thing I found was some fuel return lines were mis-machined and while still sealing well, could wiggle in about 1mm and partially block off the return port.

Besides checking for this, I will also hook up the scanner and monitor all of the related specs and write them down, both when it is running normal and when it is doing this pogo-bounce crap. Does anyone else have any other suggestions?
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post #2 of 5 (permalink) Old 03-21-2014, 12:07 AM
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Re: Intermittent fuel pressure fluctuation

Have you done the blue spring kit yet? The factory fuel pressure regulator spring is known to be weak and just get worse as time goes by. Ford released an updated kit with a stronger spring.

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post #3 of 5 (permalink) Old 03-21-2014, 07:51 AM Thread Starter
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Re: Intermittent fuel pressure fluctuation

Not yet. I've had the pressure gauge hooked up for about a week now and it never did this at all before. I do have the blue spring kit, but am holding off installing it for a couple weeks....I'll be doing a bunch of work under the hood, all preventive stuff like flushing the coolant system, installing bypass filters, etc.

I've been doing more research and am wondering if it's possible I have some crap in my filters. I don't have any loss of power though. I also read something about a secondary spring in the regulator. Never hear about this before. ???
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post #4 of 5 (permalink) Old 03-21-2014, 11:20 AM
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Re: Intermittent fuel pressure fluctuation

You know that little plastic cup thing that comes with the blue spring kit, well maybe the one on your truck is damaged?


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post #5 of 5 (permalink) Old 03-21-2014, 11:28 AM Thread Starter
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Re: Intermittent fuel pressure fluctuation

Guess I'll find out! lol
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