1977 f100 wont start
Asked by geoman77 Dec 29, 2015 at 09:10 PM about the 1977 Ford F-100
Question type: Maintenance & Repair
replaced cap,rotor,ign module,coil and start solonoid ,battery truck will turn over but not start no spark after trying some troubleshooting i noticed i had no spark when turning key and releasing but if turning key to start and return back to off position ill get a single nice spark so thought it was ign switch just replaced key cylinder and switch still no start i am stumped mind you i am just mechanical but not a mechanic just pickin your brains thanks
9 Answers
AND THE BRAIN BOX IS OK...THOSE THINGS ARE CHEAP NOW AND FAIL ALOT..
agree.brain box on fender very common to go bad.and check coil?
The 1977 is probably a 351 and has a carburetor, That little black box on the fenderwell is the voltage regulator, it does not have a PCM or computer
its silver,and its an ignition box
Ok, it's your truck but what does an 'ignition box' do'?
It is probably the coil rather than a "brain box".
The box you all are talking about on the inner fender-wall is the Ignition Control Unit, It has two big plugins on it, silver in color. Guaranteed thats the problem.
get rid of that old dis, go to a one wire coil dis is all togather prom fourm it sove my problem
It is the ignition coil getting too cold in the winter time and not allowing a spark to discharge. I tried everything including cleaning the battery cables and the top of the battery going through the wiring harness and checking for a defective wire testing the coil testing the ignition box and checking the reluctor in the distributor. Everything looked perfect but it was the coil. At very low temperatures the coil can fail to operate. I attribute that to newer and cheaper type coils being made. The fluids they're using or not keeping from freezing and when the coil is froze it can't operate properly. I took a warmer coil from my garage out to my truck and it started right up.
