JUST BOUGHT A 85 F250 6.9L AND IT WON'T START! IT'S ABOUT 15 DEGREES OUTSIDE. WOULD IT BE OKAY TO UNPLUG THE BLOCK HEATER AND LEAVE IT SIT UNTIL IT WARMS UP OUTSIDE? OR SHOULD I KEEP IT PLUGGED IN FOR HOURS AND HOPE IT STARTS LATER?

 

i wouldnt unplug it, the fuel could jell up on ya then itd be a mess, it might just be too cold out side, i have a 99 7.3 and its about 10 here and mine wouldnt start, u might check your batts thats the reason mine wouldnt start.

 

how long been pluged in. takes a lot of battery to get it to turn over also.

 

what cca battery is in it i had 750 cca bats and truck didnt like to start. jumped up to 1000 cca and fires up nicely now.

also make sure the glowplug system is working correctly.

have u read the backside of the sunvisor that says cold weather starting procedure?

 

YEAH I READ THE PROCEDURE AND FOLLOWED IT CORRECTLY BUT IT STILL WOULDN'T START.

 

let her plugged in for a couple hours, it wont hurt anything. sometimes you gotta cycle the plugs a couple of times, and i would concider some new batts, being you just bought it and don't know how old they are. being pluged in will only hurt your wallet a bit, but it shouldn't be too bad. mine stays plugged in most all the time and i don't really notice it in the bill much.

 

test and make sure block heater is working also. take a multimeter and test restance at the plug. if no restance block heater is shot. being an 85, u should not have the bad blocks. early 6.9 blocks were prone to cracking around the blockheater.