HPOP problem?

[grabowskimech]

Hello everyone. I've recently been experiencing a rough idle and low power at initial acceleration problem with my 99 F-450. I hooked up some guages and found low pressure oil pump to be delivering 20psi@idle and 42psi@2500rpm. Starting from idle the engine seems to stumble upon acceleration and tends to smooth out as you reach higher rpm. Checked fuel pressure and found it ok @ 60 psi steady. High pressure oil pump pressures seem ok with a reading of 800psi @idle and going up to 2600psi@2500rpm. The only thing I noticed is that the needle on my guage wasn't holding steady which makes me think that the hpop isn't putting out enough volume or may possibly be aerating. I also noticed the engine turns over more before it will start than it used to. Have to get back to the shop to check for codes, but was wondering what you guys think, HPOP shot or not? Oil levels in hpop resevoir and engine are good.

99 F-450, 7.3l, Edge programmer.

[SCUFFY828]

you did say this was an initial start up cold start concern correct

[grabowskimech]

Cold start a little harder to start than when warm, but, still harder than normal to start when warm. Idle rough and low power when warm and cold alike. Rough idle doesn't change with HVAC system on or off so load doesn't seem to be a factor.

[SCUFFY828]

is all maintenance up and have you been able to pull codes

[FionaThe02PSD]

20 PSI @ idle, cold or warm? Big difference in my opinion.

If it's cold then I believe you have issues but if warm it might be something else. Does anyone have the spec. for the idle pressures?

[grabowskimech]

The oil was changed last week, new air and fuel filters, can't get codes until I get back to shop tomorrow. I think the minimum allowable oil pressure is 12 psi but am not sure. Pressure tests were done with oil warm. Also, I found the high pressure specs online to be 4-500psi@idle, and up to 3600psi full load. Like I said, the needle on the guage wasn't holding steady(very jumpy when at higher pressures). I'm a heavy equipment mechanic, and I know that usually when testing pressures on high piston pumps, the needle on the guage usually holds steady, but I am not sure on powerstrokes.