Learn from my mistake:
I know most of you are geniuses and would never do this but my attempt at a cheapo anti theft measure might have cost me two brand new fuel pumps, two batteries and a new alternator!
So i bought this cheap fuel pump relay on Temu (I know…) that has an integrated on off switch. All you do is pop the old one out and install it. I did so, in the on position , the truck starts and runs, in the off position truck will not start. Anyway, when i git up yesterday, truck would not start- batteries were dead dead .9 volts!! Jump started her and after running about 5 minutes i smell burning plastic. I determine that its coming from my alternator. I check it with IR temp gun, the housing is 280+ degrees and the engine aint even warmed up!
Put the battery charger on and truck and it draws 30 amps fir 6+ hours and then sits there at 9 amps all day.
Stumped, I remove charger and continue prepping truck for trip, at first i thought I left some lights on all night. Figured i was gonna have to get new batteries. When night falls, go back out and see if something is on, had the hood up, all night and thought the courtesy light did this (it doesnt work most of the time) Then I hear it. sounds like water running, continuously like WTF? Truck is off, no key in ignition. Crawl under rear tank FUEL PUMPS ARE RUNNING(both of them, brand new, just installed a couple weeks ago)
The cheapo anti theft relay has only 2 pins, the oem relay has 4…When that relay is installed and switched to on, the pumps run. continuously regardless of truck ignition switch position.. So they ran all night until the batteries were dead. Truck now starts and runs. I figure the pumps ran fer at least 6 hours until both batteries were dead, and they ran all day yesterday while i was trying to charge the batts. I dont know if they were damaged, tanks are full, so they didnt run dry.
Questions:
Should I trust the fuel pumps? I’m planning a trip to remote National Forest….
Shouldnt a new alternator handle the load of two dead batteries for a few minutes?
I wonder if the relay would have worked properly if i had flipped it opposite direction? (it could go in either way)