Good Evening Fellas
I have been searching and searching on here trying to find someone else that has had the same problem as me to no avail. I recently purchased a 99 F-450 auto 2wd with 178 on the clock that "needed injectors". The truck was in obvious distress when I took it for a short test drive but i got it for cheap and couldn't turn the offer down. So what the truck is doing is starting very hard but ones she stays running it will idle all day long and sounds great but if you try to drive it or even hold it at 2000 rpm it will start losing power after about 20 seconds. If you keep leaning into the throttle it start pouring white smoke out the exhaust and will eventually go down to a little less then idle with the go pedal on the floor and dumping white smoke and as soon as you let the pedal up she dies. Once it dies it takes some cranking again before it will come back to life and runs pretty rough for 30 seconds before it will idle right again. So first thing I did was unhook ICP sensor, same result, changed CPS, same result, Hooked fuel pressure gauge up and done the "hutch mod", fuel pressure is 65psi all through its fit, buzz tested injectors, all sounded good. So what i finally figured out today is im running out of oil pressure and draining the HPOP reservoir and thats when it starts its fit. I hooked a manual oil pressure gauge to it and at a cold idle its running 45psi but if i take it to 1000 rpm or higher it just totally drops to about 5psi. So the first thing i done was added about 2 quarts of oil and jacked the back end up about 8-10 inches (all the taller my bottle jack would go) and still the same result, so i dropped the oil filter to look at the little screen thing (dont remember what its called) and it was there and looked fine. So i am really leaning towards the LPOP being the culprit here but just dont understand the 45 psi at idle then going to 5 psi that quickly. Hopefully somebody can help me out or maybe point me in another direction??? I have 3 of these 7.3s and love the trucks but havent ever had any problems this in depth with them. Thanks in advance for the help!!! -Shawn

 

You could pull the lpop for an inspection. It's free and not difficult. Just have to undo the belt, pull balancer, and there's the lpop. 4 bolts and some light wiggling should slide off.

 

Thats next on my list to do to it when i get a free moment, maybe tomorrow night.

 

If you decide to go that route, I have attached 2 PDF documents and the image below from the Ford Service Manual for you to use.

 

Thank you very much for that information!!

 

Well pulled the oil pump today and it looks pretty good to me. Took a feelers guage to it and checks out to be good but I'm going to be replacing the pump anyway with the mellings pump since they are decently priced and it definitely shouldnt make things worse. Do you guys think there could be anything else going on with this truck that's causing the oil pressure to do this? I have a feeling I'm going to have to yank the motor and pull the pan even though I was trying to avoid that.

 

You could take apart the oil pressure relief valve just to make sure the spring isn't broken or maybe trash holding the ball off seat.

 

Is that the one right above the oil filter or is that the one on the block side of the rear oil cooler housing??? I'm really banging my head here on this one.

 

Let me go check the spare... It's under the filter, the SD's are held in place with a snap ring. Earlier models were pinged so no way to service or inspect.