I've got a guy I work with at the base and he's having a ton of problems with his 7.3L. SO...i thought this would be the best place to find out some answers.

When first started in the morning the truck idles fine but once he actually steps on the throttle it dies. It is throwing no codes at all.

I'm thinking that it could be a number of problems, lift pump not being able to supply the main fuel pump with enough fuel, causing it to starve itself or a weak injection pump not opening up the injectors or a bad cam positioning sensor. Any thought?

I know it's not a Cummins but hey, i know some of you here have once had a Power Stroke, me included.

 

does it restart and then keep running or it dies everytime? if it will re start then its got fuel drain back and air is getting in also the 7.3 is prone to run issues if the oil gets old check the system over for any sing of a leak

 

it will restart but you have to crank and crank on it for it to fire (15-20 seconds). There isn't a guarantee is isn't going to dye again. Because it has dyed right after restarting it while going down the road.

 

sounds like air getting in ,check all the return lines for any wet areas like right rear head . when was the last oil change? does the oil smell like diesel? that could be a bad injecter Oring most of the time its a oring on the return letting fuel drain back to the tank thats why it dies it starts on fuel in the filter and lines then starves out till you prime it with the LP

 

I'll have to have him do some more digging to see if that's the case. I told him that it HAD to be something to do with fueling due to it starting and running but dying when putting a load on the motor. I can def. see your point about it maybe being an O-Ring and letting air into the fueling system. I orgianaly thought that he could of had a loose injector alowing air into the system also, but then thought against it once i rode in the truck with him.

Even thought the motor was warm the motor was shakeing the truck while driving down the road, as if the motor was acting like a retard and out of sequence somewhat. It's just over all not running good and the whole shaking syndrome could be a result of having air in the system, right?

 

sounds like CPS... mine did close to the same thing. I think Ford has since issued a recall or TSB...

 

Sounds like an IDM issue, or a bad valve cover gasket. Look for the plug in the center top of the valve cover, wiggle the wiring at the plug with the engine running to see if it clears up or worsens. IDM is the injector driver module, it need around 48 volts to work correctly, anything under 40v and all kinds of drivability concerns occur. A cam position sensor will cause the same issues without throwing a code. There was a recall on the cam sensor so check with a dealer to see if the campaign was performed on his truck. I don't think you have an injector oring issue at this point.

Keep us posted, we will help you get it straightened out.

 

Just ran into a similar problem with my bros 7.3 2 weeks ago. It would start and idle but when under load it wouldnt get out of its own way and sometimes die. I put a new air dog on it and same issue. We dropped the fuel tank and the screen on the pickup was alittle dirty but there are two micro screens on the inside of the sender that were clogged solid...Cleaned up and it runs like a new truck...just my input.

 

These trucks also have an issue with the o-rings at the top of the mixer module in the tank leaking. Just above the two pickup screens. When this o-ring goes bad, it causes the truck to starve for fuel between 1/4 and 3/8 of a tank. It will start running rough, blowing blue smoke, and have NO power at all.

 

Sounds just like a Ferd to me . I couldn't help it but you definitely have a fuel issue. Hope your "friend" get's it worked out.

 

Check fuel pressure at filter housing. It has a schrader valve for that. As others ahve said, the crankcase pressure sensor will shut the truck down like you jsut turned off the key, but will immediately fire back up normaly... IDM can act goofy to the point where only one bank of the engine will run... Or can get a no start condition if it completely fails. Has the fuel filter been raplaced recently?
I would get the stuff to check the HUEI rail pressure, fuel pressure, the IDM can be checked by unplugging the valve cover harnesses once at a time with the truck idling. And dump a quart of ashless 2 cycle engine oil in the tank...