03 7.3 no start high pressure leak

kbomb2788 · September 7, 2015

Hey guys. Got a 7.3l with no start. Checked pids and not building high pressure (was around 300 psi, replaced icp and ipr truck went up to 400 and acts like it's going to start but doesn't) Disconnected right head high pressure rail and installed plug and truck started with ipr duty cycle at 22. Removed right valve cover, I had a truck that had similar issue and the problem was#1 injector the return port was stuck open and oil pressure would vent out causing no stat, I removed all injector vent shield and crank over and did not see oil come out (key off) with key on they squirt oil out. I'm not that experienced with 7.3l, what should I look for, is there an air test?

lmorris · September 8, 2015

Normal oil squirt would be a short and evenly timed. If it's a constant flow then that injector is bad. Also check where the injectors go into the head for leaks. Also check those 2 small oil rail plugs, have seen those o-rings leak too. Personally I have never air tested a 7.3L. Just plug the left side and crank it over.

Bruce Amacker · September 8, 2015

If the upper o-ring leaks it will be visible with the VC off. If the center o-ring is leaking on a 99-03 it leaks into the fuel rail so it's not visible or evident except if you take a fuel sample or watch FP at that head. On 99-03 it is returnless fuel to the heads so you won't get black oil in the fuel filter, on '94-98 the head rails return to the tank so oil will be evident in the fuel (if the center o-ring leaks).

–Weatherhead 7897 is the adapter fitting to air check the HP oil at the head ports.

–Thread is ½” NF with an o-ring, also known as 5/16” inverted male thread.

- If you go to the hardware store they'll also have a fitting for a couple of bucks.

–You will need to supply a gasket for the bottom of the fitting.

Good Luck!

kbomb2788 · September 13, 2015

Thanks for replies, I put new o rings on all injectors (I thought I saw a leak from the top of the injector where it seats against the head but now I think it's from the exhaust port running down) I dead headed the pump and got 3600 psi. I would have to get my fuel gage set up for fuel pressure test...but just from all, what is left and is it reperable or cylinder head needs replacing