Hello, I have a 1994 f350 7.3 that is losing prime. Here is the rub. I starts cold usually but after warming up if I let it sit for about half an hour it will not restart. There is fuel pressure at the schreader valve when it is running. The fuel level in the filter bowl stays full. I have run beyond my personal knowledge level and am seeking wisdom. Does anyone have an idea what is going on?
Thanks, Bobb

 

Which engine do you have? The 7.3 IDI Turbo, or the 7.3 Power Stroke?

 

Turbo with direct injection. Like there is no fuel getting to engine but there is fuel at the filter bowl. Cranks fast but no ignition. Is there only the one fuel pump on this truck under tye turbo?

 

I believe those early 7.3 PowerStrokes had a mechanical fuel pump that was somewhat prone to failure. Honestly I do not know much about the specifics of those engines.

However, there is very active 1994.5-97 7.3 PowerStroke section on this forum just below this section. I'd recommend you go there.

 

Has the truck ever started hot? does it spit and sputter when it does? could be a couple of things, first guess is...

Injector Pressure Regulator problem. The O-rings in it get old and tear. when cold it will build pressure but once warmed up they let oil past.

Second is a drain back issue in the HPOP.

These motors use Hydralic/Electric Unit Injectors. There is a High Pressure Oil Pump "HPOP" and a low pressure fuel pump. The pump under the turbo is the low pressure fuel pump and between the fuel bowl and the front of the motor is the High Pressure Oil Pump.

Unless your familiar with these motors changing a set of IPR rings prolly isn't for you, its not hard but its not easy to explain over the internet.

Diesel Rod