I have been around the 7.3 L diesel for a while, but only in a parts changer sense. Now I own one. It has a complete miss on the #8 injector. Should I go straight to the injector? I have had suggestions that the valve cover gasket may need replaced. Is there any way to tell whether it is the injector without tearing it apart? Help?

 

What year PSD?

You can ohm test the injector though the UVC harness connector.. Problem being,, that the injectors can fail in two ways, electrically and/or on the mechanical end. So you could have a set of injectors that ohm out fine, (as long as the harness/connectors are good) but may have a failed mechanical end causing the misfire.. Or, depending on the M/Y,, burned harness issues or possibly even the retainer clip sagging and allowing the UVC harness to move off the connector that may through off the test values.. Best way to diagnosetheinjectors is to use a scan tool and run both an injector 'buzz test' for equal solenoid pitch (audible tone) for the electrical side, and a 'cylinder contribution' or performance balance test for the mechanical end as well as healthy injector components on both sides.. As a start point, youcouldtry and ohm test the injectors though the UVC, then work inward checking the connections and finally the injector itself.. If the ohm values are matched for the bank,pull the valve coverand look at the oil being exhausted out of the injector manifold on #8.. Generally if the mechanical end is failing the oil being exhausted will be a higher volume than a heathy injector..

 

2001 Ford F350 PSD.
Buzz test OK.

 

First thing would be to read the stored/pending codes for direction.. If there's any injector circuit codes,low/high resistance or high/low side shorts,opens,IDM driver codes it generally will point you towards harness connector problemsor IDM issues.. Then run the buzz test (if you didn't do it first) for the audible check, and if a circuit problem or a bad injector solenoid it'll be heard during the test.. The buzz will activate injectors from 1 through 8 cylinder count.. Next run the cylinder balance test to not only varify #8 contribution failure, but to check for any other cylinder running/performance problems so not to have to repeat any repairs.. While being tested, this would be a good time to run the glow plug test fora balanced amp draw .. If you only get PO284 chances are its just a bad injector.. The later build 7.3's didn't have the volume of harness issues the earlier builds had.. Certainly not unheard of though....