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for the scoop on the glow plug system.
There's only one Glow Plug Relay, so if you jumpered the right one, all your GP's should have worked, not just one bank.
The relay toward the front is the Intake Air Heater relay, and would also cause the voltage to pull down. It heats the intake air for extended idling in cold conditions, but not for starting. If you heated it up with your jumper, it would help starting, but not nearly as effective as the glow plugs.
Your GPR probably has bad contacts and works intermittently if it started OK 5 minutes later.
First truck -- 1929 Model A Ford pickup, restored from ground up. Wish I still had it!
99.5 F250 PSD Supercab LB 4x4, ZF-6 w/SB Con OFE, 3.73LS, Boost & pyro gauges, Swamps S175/146 injectors, DP 80 HP Econo PCM (classic version
), AIS, coolant filter w/"hokum" bracket,
regulated return, heated mirror mod, lighted cupholder, Marinco heater plug-in.
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