No oil pressure at idle, need help!!!

kmesaeh · Oct 14, 2011

I just changed #3 injector on my 99.5 F-250 with 7.3. Before taking it for test drive I had pressure at idle, drive truck for about 3 to 4 miles stopped at stop sign and noticed that I no oil pressure when idling. It also seens to be low on power and running rough, could be due to air in system but not sure. Did not have the issue before replacing the injector.

tmillburg · Oct 14, 2011

have u checked oil levels in HPOP res?...iam drawing a blank for some reason, but dealt with problem before....have u cranked with glowpulgs out....to prime?

Jason · Oct 14, 2011

Are you going off of the dash gauge??? I had a motor in my mustang start registering no oil pressure when it came to idle..tap the gas and it jumped up..sending unit. Being as these trucks are oil dependent to run injectors, wouldn't it not run, if you actually lost oil psi?

Blowby · Oct 14, 2011

kmesaeh said:
I just changed #3 injector on my 99.5 F-250 with 7.3. Before taking it for test drive I had pressure at idle, drive truck for about 3 to 4 miles stopped at stop sign and noticed that I no oil pressure when idling. It also seens to be low on power and running rough, could be due to air in system but not sure. Did not have the issue before replacing the injector.

I would look at what you did to replace the injector. Did you take the rocker arms off? If you did then are you sure you got the push rod back in place? Is the lifter bleeding off oil?

Wackerjr · Oct 14, 2011

or when you were installing ..and leaning over the reservoir ..you either broke or unplugged the oil pressure sensor

kmesaeh · Oct 14, 2011

I'm going by the reading from the "dummy gauge". I'll check the sending unit in the am. Did not unplug it, but could have pinched the wire leaning over it.

PowerstrokeJunkie · Oct 14, 2011

Is it possible the injector wasn't tightened down completely?

Wright337 · Oct 14, 2011

Mine did the same thing on my 6.0. If i mashed the pedal i would have pressure. Installed a guage and had plenty of pressure. It was the sending unit on mine.

kmesaeh · Oct 14, 2011

Ok, I have two new sending units that i got form work, I also picked up a connector to. I'll give that a shot in the morning.

kmesaeh · Oct 15, 2011

Ok, I changed the sending unit and the connector. i also put a mechanical gauge to the test port at the filter housing, and went for a drive. I still have the same problem, I noticed that the gauge was dropping to under 5 psi at idle. At this point, I'm even more stumped!!

BigAlsPSD · Oct 15, 2011

Sounds like a weak LPOP easy to change, pull the harmonic balancer, its behind there should be around $75

Jake · Oct 15, 2011

Pull the valve covers off I am suspecting bent/broke pushrod

BigAlsPSD · Oct 15, 2011

^^^I agree too, after remembering how this all started, it is definitely a possibility that the lifter is leaking off oil.

kmesaeh · Nov 16, 2011

Ok sense my last post I attempted to drive the truck arround the block, lost oil pressure. would not build any pressure when cranking. I changed the oil and filter, no change. I installed a new low pressure oil pump and still no change. There has to be some flow from the pump cause the filter is full. the gauge I have moves very little, not even to 1 psi, but comes off 0 when cranking. I have no clue what to check/look at now.

Wackerjr · Nov 16, 2011

Man quit driving it... As has been stated before...pull the valve cover and look at the pushrods...and check that injector install....hell why did you change it in the first place?