Low oil pressure @ injectors / low boost

[repoman3809]

New to the forum So thanks in advance!

Got a 99 f350, 7.3, 4x4, repo truck with power issues.
Seems to idle fine. Seems to run good on flat ground, in the city. Take it uphill, struggles. Get on the highway, struggles to get up to speed. Put a repo on the back and struggles badly at both, though still seems good on flat ground stop sign to stop sign.
Getting on the highway she really bogs down just before 2000rpm, sometimes throws a few white puffs out the tailpipe. Back off the throttle and ease her up to speed seems to help. If I gotta climb a long hill, be lucky to get to the top at better than 10mph(highway or city/loaded or unloaded).

Had Ford run diagnostic, pulls codes for "low oil pressure at injectors"(under load) and "low boost". No check engine light, no injector codes. Before I took to Ford I changed oil, air filter and fuel filter.

After Ford, I checked oil again(good), unplugged, cleaned and replugged all corresponding sensors.
~Oil switch unplugged: no check light, no oil pressure gauge, ran same.
~Oil temp unplugged: Check light on, ran like crap.
~High Pressure unplugged: Check light on, ran the same.
~Exhaust Backpressure unplugged: No check light, ran the same.
~Cleaned sensor above the red and green "wastegate?" lines.

I cleaned all the above mentioned, along with injector plugs(in the valve covers). Drove and truck ran much better. Was able to climb hills fine. Just unable to stomp on it. Still wanted to bog down around 2000rpm and throw white smoke.

Sorry for writing a book! Just wanted to cover everything. Dont know much about diesel motor's. Thanks for any ideas.

[ajpu1983]

Check fuel pressure

[repoman3809]

Will do. Guess 47 to 55psi is the normal. Gotta admit when I changed the fuel filter I drained the housing, put the new one in, then turned the key to fill it. It didnt seem to come out of the hole fast, just trickled down the side. Course it only took 15 or so seconds to fill.

[ajpu1983]

Also make sure to have a fuel pressure testing rig that will allow you to check pressure going down the road so you can see if it drops under load.

[oldstroker86]

My truck ran great at idle and driving on flats. But would lose power under load. The little screens in the fuel tank on the fuel pick up were completley plugged with algae. I guess the truck sat for a while only had 90,000 miles and its a 2000. Cleaned them up with some brake cleaner and a tooth brush runs perfect now. Not saying this is your problem but it is easy to check and fix. Good Luck.

[repoman3809]

oldstroker86 you pretty much nailed it.

My mechanic who I had trouble getting a hold of, finally called me back. Said that with the low boost code, white smoke and other factors...95% of the time it is clogged filters in the sending unit. Also said another sign is when the truck runs good at startup for the first few mins, then starts running like crap. Said turn truck off, let sit for a min then startup again. If runs good for a few more mins then definitely filters. Turning the truck off lets the junk clogging the filters settle. Then turning back on it takes a min for them to clog back up.

Said best thing to do to fix. Take out bed bolts, raise the driver side of the bed up. Remove sending unit from top of the fuel tank. Pop white cover off the bottom of the sending unit. Remove the 2 filters. He said LEAVE the filters out and put the sending unit back together and back in the tank. Mount a inline fuel filter outside the tank. Doing this will keep you from taking the bed off and pulling the sending unit out just to clean the filter, if it were to happen again. Now you can just reach though the wheel well and change/clean the filter.

Also said dropping the tank is possible, but more of a hassle esp. if theres a lot of fuel in it. I though removing the bed was pretty easy. I have a bed liner and removing that and the 6 bolts took about 20 mins.

BTW my filters were caked with rust!

Thanks a ton for your help guys!