Hopefully somebody can help me work through this diagnosis process. My grandfather has a 1997 F2 50 heavy duty power stroke, California model. He last drove it three years ago on a trip back from Oregon ran great with no problems at all. He parked it in front of his house and it sat there for three years with dead batteries. He’s asked me to help him get it running again since I used to have the exact same truck 97 F3 50 California model. So far everything that we have done would be the normal things you would do after truck has stopped that long, installed two brand New batteries. Drained the fuel tank put 10 gallons of fresh diesel in it. Checked the oil level on both the crank case and the Hpop
reservoir . Put a new fuel filter in and confirmed fuel getting to the bowl. Looked over all wires and connectors on the engine . Had to replace the Passenger bank rear valve cover gasket connector, spliced wires together using heat shrink connectors and tried to rewrapp wires as close to factory look as possible. About 4 years ago I had discovered that the clip part was broken and had allowed the connector to vibrate loose which gave the truck a rough running condition and was really burnt/melted on the two end wires. We simply pushed it back in and proceeded to take multiple 300 plus mile trips in it before it parked. While trying to hand drain/ soak up fuel with a sponge from the fuel bowl (drain lever was not working, must be clogged) the wire for the fuel heater became loose and I decided to unplugg it so it wouldn’t short out and blow the 22 fuse (common, happened to my truck).
The problem we are having is there is no wait to start light. The truck cranks over strong but just spins endlessly. No combustion at all, no smoke. So I am assuming that the injectors are not firing due to the pcm
not working. I have been doing a lot of reading trying to mitigate this and have tried Almost everything I can think of. No wts light. Individually unplugged each sensor and checked for WTS to try to isolate a bad one. No change. Checked all fuses they are all good. Checked the main pcm
relay and was good when tested on the horn circuit . Power goes to the relay . Checked power on the gpr and it all checks out good. Tried two scan tools on the obd2 and both said communication failure.
Still learning the electrical diagnosis process and figuring out how utilize full functionality of a multimeter. Just know the basics so please if anyone has any idea of what else to check and some instruction I would greatly appreciate it.
One more concern I have about the truck is that when Turning the key to accessory it makes a faint thunk from somewhere behind the gauge cluster and when turned to on a louder THUNK come from the firewall . Intermittently the truck won’t crank when turning key to start, but %80 of the time it will engage starter and and crank the engine. Doesn’t seem to be a reason why the computer won’t power I but I have been wrong before.
Any help would be really appreciated