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When warming my truck up one day, I noticed a puddle of diesel under the engine. When I drove it (and ever since), it started experiencing fuel delivery issues. It gets slightly better as I drive, but only gets to a point where I'm capped at 100km/h on flat road and it bogs out on downhill sections, with zero fuel delivery for a good 25 seconds and a whole lot of white smoke. It has since stopped leaking fuel, though.
Would the cause of this just be the filter, or is it more likely the pressure regulator or a line? Note that I haven't had the fuel bowl heater plugged in for about a year now as it was shorting.
It's a '99 7.3 Powerstroke with 310k km on it. I only know the work I've done, which is break lines, vacuum pump, belt tensioner and front end rotors and pads.
You are coming upon 200k miles.... The 7.3 is probably due for some maintenance. It could be a combination of things going on. I'd do some research on components that may need to be changed out if you are going to open up the engine.
A common fuel leak is on the passenger side fuel line, see pic below. Over time the line can vibrate and the clamp wears a hole there. There are several good threads with pics and instructions.
Worth inspecting the yellow fuel drain lever, see if it is dry. The o rings get old. You can replace the o rings for cheap but the whole valve is not expensive.
Symptoms (low power, white smoke) sound like fuel pressure is too low. Did the truck get the Hutch and Harpoon mods? If it is still stock the filters inside the fuel tank may be clogged. If so you can temporarily clear them by removing the fuel line from the back of the pump and applying shop air back to the tank. Open the fuel cap first. The air can blow the crud off the filter for a temp fix.
It would be great to have fuel pressure numbers. A temp rig plumbed into the yellow valve would work, but I recommend a dedicated gauge install. Boring gauge when all is well, but that info answers half the diagnostic questions when things go wrong. Like now.
I believe that you need to look at the same area. The fuel drain valve. Where is the puddle of fuel under your truck. If the puddle looks like is it coming from the back of the engine and flowing down the back. know that there is a drain hole at the back of the valley. If you have 'fuel' in the valley, a known cause is that fuel is leaking from around the small rubber hose that is pushed into the fuel drain valve at the back of the fuel bowl. If the fuel puddle is located in the front passenger side of the engine at the fuel drain pipe, then fuel (as with above) is leaking at the fuel bowl drain valve. The o-rings do deteriorate over time. The o-rings in the cold on the drain valve can also shrink a little and allow a slow leak from the drain valve (either past the small rubber hose or down the drain tube. As fuel leaks out of the drain valve the fuel bowl will slowly empty of fuel and may cause the issues that you are having with air in the fuel lines. Look where the 'leak' is coming from. If it seems to be the brain valve area, a simple 'fix' may be to tighten the small bolts holding the drain valve on the fuel bowl. DO NOT TIGHTEN THESE TO TIGHT, YOU WILL BREAK SOMETHING. If the drain valve has never had its' o-rings replaced, you should overhaul the valve. Very simple to do with parts from Diesel O-rings.com. https://www.dieselorings.com/1999-20...ts/12-001.html https://www.dieselorings.com/1999-20...owl-parts.html https://www.dieselorings.com/
As for other reasons for low fuel pressure, I've experienced two scenarios not yet mentioned.
1) Fuel pump - yours is getting old and tired, and may just need to be replaced. When mine went out, I could not get above 45 mph until I replaced it.
2) At 21 years of age, the plastic pickup assembly components inside your tank may well have simply broken down into little bitty pieces, and be plugging the suction tube (or trash ahs gotten inside the tank creating the same type of pluggage). When I and my son got to this point, we first tried blowing out the fuel line backwards into the tank with a compressed air hose, and it worked... but it is only temporary until you get the trash out of the tank.
