Need help, we have a 2003 f250 2wd that was, unfortunately, serviced by a local shop. We have changed our location and are doing our own filter/fluid changes now.
The problem we have is it is lagging at higher speeds to the point where we can't think of passing other vehicles anymore. I changed the fuel filter and removed the AFE st.1 air intake and replaced with a new stock unit. The fuel filter was extremely dirty and I noticed there was no O-ring on the filter! The bevel ring was there but obviously the service shop didn't know where that O-ring went because it wasn't there!
Would that have allowed dirty fuel to flow into the injectors and would that be what we are experiencing with the no-go on passing?

 

When was your last oil change? What type/brand/weight of oil are you using? 7.3 PSD injectors fire off (high) oil pressure, so low oil level, worn out oil, etc. will effect performance.

Do you have a fuel pressure gauge connected so that you could see what is happening at higher RPMs? Dirty/worn injectors could cause you to have low power, but how does the truck idle? If it idles fine and power is good at low RPMs, I'd look at fuel supply/pressure. There could be a clogged fuel filter. Originally there is only the 1 filter on top of the engine, but many people add 2nd filters in to keep fuel clean. Follow your lines back to the tank and make sure you know if you have a second filter or not. It could also be your fuel pump getting worn out. Idle & low RPMs are not placing as high of a demand on the pump, so that could be a cause.

It may not be just one thing either. Even if you find a dirty secondary filter, check the pump and your fuel pressure to be sure you do a complete fix.

 

Thanks for the reply, I am the original owner and 1 of my employees now drives it. There is only the one fuel filter as the only mod I did when I was driving it was the AFE intake. As for the oil, I have a 55 gal. drum of Mobil 1 TD syn. at the shop (we have 1x 7.3, 2x 6.0, 2x 6.4) and oil was changed less than 4000 miles ago. no fuel pressure monitor and idles just fine. I did manage to drive around town after replacing the filters (air/fuel) and didn't notice any problems. He drove after the changeout and said that it still doesn't have the getup and go it used to. I will get a fuel pressure gauge going to see what is going on at the higher rpms.

 

An Autometer 4363 is more expensive but is electronic and can then safely be put in the cab. They can be had off ebay for ~$200. The fuel bowl adapter (you'll need for either electronic or mechanical gauges) can be had from Replacement O-rings for Ford Diesel Engines (Guzzle92/Bob is a member here and the owner of that site). I have bought from Bob and the service and goods are absolute top quality.

 

Very likely it could be fuel pressure as Brendan mentioned. Even at very low fuel pressure you won't notice it at idle. Here is another option to the Autometer as well.

Riffraff Diesel: Black Face/ Red Pointer/ Black Bezel

 

Hopefully the injectors are okay. It does sound like you were sucking dirty fuel into them. The only way to fix them or know for sure is to pull them and have them flow tested. I think Brenden has you looking in the right direction for now though. But if you don't want to monitor the FP full time, you can set up a temporary mechanical gauge with a piece of fuel line so you can look at it through the windshield. You just don't want a fuel line running into the cab for obvious reasons. The electrical type is much more expensive, as Brendan pointed out, but they can be safely ran into the cab.

If the fuel pressure drops more than about 10-15psi at WOT, then it's likely a tired fuel pump. It should be around 60psi at idle, then drop some at WOT.

 

Nice price on the gauge!!! I mentioned the Autometer 4363 simply because that's what I'll be getting to match my other gauges.

Also, with the electronic gauge, you have the option of getting a 2nd sending unit and tapping both ports on the fuel bowl and wiring up a switch to choose which you want to monitor. Why bother doing that? One port is pre-filter, the other is post-filter. If you saw a significant difference between the two readings, that could indicate that it was time for a new fuel filter. Plus it's just cool.... hahaha

 

That's a cool idea man. One of the guys up here has the EV2's so we might have to try that.

 

Stolen from CSIPSD; wasn't my idea, just so's ya knows!!

 

If it is pressure, you need to add two gauges.
There are two plugs on the back side of the fuel bowl. The top plug is pre, the bottom plug is post.
The pre gauge tells you if the fuel pressure is good from the rail pump to the filter. The post gauge tells you if the filter is feeding the HPOP or is restricted and you need to change the filter.

 

If it is pressure, you need to add two gauges.
There are two plugs on the back side of the fuel bowl. The top plug is pre, the bottom plug is post.
The pre gauge tells you if the fuel pressure is good from the rail pump to the filter. The post gauge tells you if the filter is feeding the fuel rails or is restricted and you need to change the filter.

 

I'm voting clogged pickup screens in the fuel pickup.

 

I'm leaning this direction too. Bad fuel injectors will cause problems at every rpm, not just passing gear. Lack of power at highway speeds or passing gear usually means a fuel delivery restriction.

 

I just did my intake fuel pick up mod, and my screen was clogged to the point where fuel was being sucked in through that little orange rubber valve looking thing about 1.5" above the screen. I found out because I ran out of fuel about 150 miles before I normally would, and 1.5" of fuel in a 55 gal tank is a lot of unusable fuel!

 

Thank you!