Medium and Heavy Trucks
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Hi Brett, My name is***** will be glad to try to help. Check for the inline ECM fuse between the battery box and engine ECM and for corrosion in the harness for a loss of power to the ECM. also test all your fuses and relays and their connections for any loose connections. If okay test the key switch for power in and out in all positions for a possible faulty key switch. Test your batteries and inspect, ckean, and tighten all battery to starter connections including all grounds as well. Let me know
Hi Brett, Thanks for the update. fuel pressure should be 58-63 at idle and up to 76 PSI driving under a load. Verify good fuel pressure. If low it can be a faulty regulator or injector o rings, leaks, a restriction between the tank and pump, or faulty pump. Check for bubbles by installing a clear hose between the tank and pump and verify fuel pressure by tapping into the filter housing.
Speed timing sensors in the front cover can also cause hard starting if there is a loss of signal and also if the cranking RPM is too slow. Let me know