I own a 1992 F-350 with the non-turbo 7.3 IDI with the 5spd. The truck has just past the 200k mark. My truck I can normally run the fuel tanks deep into the red on empty on my fuel guage before switching. A couple weeks ago as soon as I get close to a quarter tank, it begins to run rough. I guessed that maybe I had gotten some water from the station so I started using the rear tank. A week later it started doing the same thing on the rear as well. I am not sure what is the problem is because the kicker is that as long as you go down the road I can continue to use the tank, but as soon as I get to a stop it will run rough and will even sometimes stall and it will take turning over like repriming the fuel system after a fuel filter replacement. As soon as you refuel the problem goes away. I want to say the Mech. Fuel pump is faulty not having enough strength to continue drawing but not sure. I know it could be the guage as well as I have heard of a problem with the pickups in the tanks breaking, but I never heard of both at the same time. I have already removed the fuel filter and it was full with very minimal junk (the normal) I change the fuel filter every other oil change so I know its not the filter. At 165K I had to replace the IP so I know its not that either. If anybody has an idea as to what to try first or have had this problem before please help. I am not an ASE mechanic but I did work as an auto/diesel mechanic before being laid off so I can't get too serious without being 100% sure since money is really tight.

 

While still being new to the diesel thing, off hand my first thought would be the fuel moving around in the tank. When your cruising it's level and the stop and go causes it to slosh around letting it suck in air. The strainer socks on your pickups may be getting plugged which is why it didn't happen before. I try not to run to far past 1/4 tank to avoid getting air in the line.

 

I say i run it into the red on E but i use my trip odo. because when i first got the truck I ran it as far as it would go til it started skipping but with this problem i lost almost eighty miles on the tank I used to get 250 miles on my front tank before it started skipping. Now im lucky to get 175 before it starts going fool.

 

I'm wondering if it could be an air induction problem that is more prevelant when the tanks are near empty (less gravity pressure in the tank) vs. full?

 

Im pretty sure there is nothing hindering the air induction. Its factory and I change the air filter religously every oil change whether its clean or not. I'm thinking its the fuel pump.

 

It's air intrusion not induction ...

However it does sound like you are getting Air intrusion by way of the pickup tubes in the tank.

And yes, it is very likely that both pickup tubes are leaking!
If they are of same age they'll likely fail around the same time.

Pull the units out of the tanks and either replace or repair the tube with hose... Be sure to V notch the end of the hose so it cannot suck up against the bottom or sides.

-Enjoy
fh <font color="#FF0000">:</font> )_~

 

I think Festus is on to something. This is a classic symptom of a broken off fuel pickup tube. If thats what happened, the solution is to drop the tank and replace or if possible, repair the fuel pickup tube.

 

Thanks as soon as I can slow down I'll jerk the rear tank since its already bout empty and its the easiest to get to. While I'm at it does anybody know a company that may offer a serpentine belt conversion for my '92. I've looked around but can't find any junk trucks with the brackets and pulleys. I want to convert it from v-belt to serpentine because I want to have just a single belt, and my truck has dealer installed a/c and I want to change it to factory.

 

Some say it's eaiser to pull the bed and do them both at the same time, the tank straps are notorious for breaking and can be hard to find.

Though bed bolts can be their own nightmare!

-Enjoy
fh <font color="#FF0000">:</font> )_~

 

hey check the fuel selector valve for corrosion in the connector thats where the wiring for the fuel level sensors go through when you switch tanks

 

look very closley at the hutch and harpoon mods done on 7.3s. if you have to do two tanks, take the bed off. the hutch mod, is super easy, greatly simplifies and improves the fuel system. the harpoon allows easier fillups by cutting off a too-long vent pipe.

the hutch is the way to go. will fix your bad pick up tube and eliminate the intank filters.

 

I agree....I tired to replace the bolts when I had my bed off and Ford told me that they dont make them anymore.....hmmmm...