I have tgis same problem as well. I tested the relay 4 times and the voltage was good. I also checked the resistance on the glow plugs and the drivers side were all .8 ohms and passengers was .7 ohms. Yet I still have the same problem starting. It wont fire the first time but if I cylcle the key four times it does. This leads me to believe it is still a relay issue?
2001 F-350 CC ZF-6 DRW 4x4 4.10, 7.5 ton modified J&I flatbed dump, Rifraff frx, Garret BB, Non EBPV pedistal, IH bellowed pipes, DP tuner F-6 chip, SB dual disk, Midwest short shifter, Ranch Hand legend front end, Ford AIS, AGR super pump, AGR gearbox, Mile Marker 10k hydraulic, 4 inch turbo back, Riffraff boots, Pacbrake, 2WD Low mod, ISSPRO boost, pyro, trans gauges, DIY gooseneck/bumper hitches, Prodigy brake controller, 4 leaf overload springs, Viair compressor with horn, Dieselsite 203* t-stat, ESOF lines, DIY Oil HX mod, 08 mirrors, 245/70r19.5 tires. All led lights.
1997 F-250 EC SB ZF-5, 4x4, d60 front swap, E-fuel, Full Force stage 1s, DP F-5 chip, Swamps IDM, 6637 filter, 3in downpipe to 4 in exhaust muffler delete. Leveling kit on 18 weld wheels and 35's, all led lights, Reunel Rear bumper, Flatbed w/stackrack
AE in Northern California