We have a 99 F550 that has over 320,000 miles. We are running straight exhaust due previous power loss. That time the Cat was plugged. Now it is loosing power again. It is especially slow when cold, after idling for a few minutes, or after being parked with engine off but not cold. It also seems to pop out of the exhaust durring this time of less power. Even after it gets its power it doesn't have as much as it used to. Even while on the highway sometimes it dropps power and I can only get it to 55 mph then it comes back. Is the engine just wore out due to the low 4.88 gears at 65 mph it runs about 2500 rpm, and 80 is close to 3000. I have seen a lot of F650s & 750s with new or rebuilt PSDs after 300,000 miles. Also we are looking for a 04 or 05 F450 are many people having problems with those years. I have seen many people posting problems with them on other forums but I know that the ones with the problems are the people that complain. I just want to know about what percentage of 04 & 05s have issues.
99 550 power loss & 04-05 reliability
- Thread starter gt40freak
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oil_burner
SDD Junior Member
Have you checked fuel pressure? lift pump possibly going south?
94f450sd
certified nutjob
when was the last fuel filter change,oil change?what color was the fuel in the filter bowl?if it is oily/black its highly likely youneed injector o rings.
whatabudro
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I may be way out of bounds here, because I'm assuming a 99 F550 has an EBPV (exhaust back pressure valve) but here we go. The valve is there for the sole purpose of shortening the time it takes to warm up the engine. The valve closes and opens by the control of the ecm to add an additional load to the engine by closing a butterlfy in the exhaust side of the turbo. Try inspecting the EBPV and the EBPV tube, its more than likely clogged with soot. Everything you mentioned could be caused by a closed or partialy closed valve IMO.
Here's a picture of the valve before and after on mine. I simply gutted the entire system on mine.
There's more to it than just removing the butterfly, but that should give you a visual of what I'm talking about. Also, I never messed with the tube on mine, but that could be your entire problem and its an easy fix from what I've read. Someone might chime in on whats involved in cleaning the tube.
I know it is not the EBPV I have already checked that could it be the HP oil pump. I just remembered about a year and a half ago the oil fill cap was left off and used on a rainy day. After that it lost power but we changed the oil and it got better. Could the HP oil pump have suffered some damage then but now getting worse. I don't remember how long ago it was but it wasnt that long ago that I changed the oil, oil filter, fuel filter, and air filter. The fuel in the filter was clean. How do you check the fuel pressure?
