86 F150xl 302 will start but wont fire HELP
#1
86 F150xl 302 will start but wont fire HELP
My truck was running fine for a good while but after one drive I parked it for the night then went to start it in the morning and it wouldn't fire. Tried starting fluid in the intake and not even a sputter. I read up a little bit on what it could be and went ahead and replaced the ICM but that didn't solve the problem. I'm thinking its the coil now but don't really know how to troubleshoot whether or not its that for sure. Help?
#2
(assuming the starter was turning the motor over) pull a spark plug out of the block and (using heavily padded gloves and at night...) press the side of it against the block away from the hole where u pulled it out of and then have someone turn the key on it. if the plug sparks then your electrical is fine and its time to look at your fuel delivery. on that rig the fuel pump is mechanical and mounted on the driver side of the motor should be a brass looking thing with two tubes coming straight up out of it. check it for fuel leaks, a puddle underneath etc. if you dont get spark then right above the fuel pump is the coil, make sure the connection on it is secure and maybe even pull it off and make sure the tip of the coil isnt too chewed up from extended use. then (without disconnecting any spark plug wires) pull off the distributer cap and check the rotor (small plastic doohicky inside with a metal contact in the center and a flat tip that spins and contacts the underside of the cap) make sure it's not too chewed up. at this point you have covered the basics that could keep your rig from firing one day and not the next.
#3
(assuming the starter was turning the motor over) pull a spark plug out of the block and (using heavily padded gloves and at night...) press the side of it against the block away from the hole where u pulled it out of and then have someone turn the key on it. if the plug sparks then your electrical is fine and its time to look at your fuel delivery. on that rig the fuel pump is mechanical and mounted on the driver side of the motor should be a brass looking thing with two tubes coming straight up out of it. check it for fuel leaks, a puddle underneath etc. if you dont get spark then right above the fuel pump is the coil, make sure the connection on it is secure and maybe even pull it off and make sure the tip of the coil isnt too chewed up from extended use. then (without disconnecting any spark plug wires) pull off the distributer cap and check the rotor (small plastic doohicky inside with a metal contact in the center and a flat tip that spins and contacts the underside of the cap) make sure it's not too chewed up. at this point you have covered the basics that could keep your rig from firing one day and not the next.
#4
(assuming the starter was turning the motor over) pull a spark plug out of the block and (using heavily padded gloves and at night...) press the side of it against the block away from the hole where u pulled it out of and then have someone turn the key on it. if the plug sparks then your electrical is fine and its time to look at your fuel delivery. on that rig the fuel pump is mechanical and mounted on the driver side of the motor should be a brass looking thing with two tubes coming straight up out of it. check it for fuel leaks, a puddle underneath etc. if you dont get spark then right above the fuel pump is the coil, make sure the connection on it is secure and maybe even pull it off and make sure the tip of the coil isnt too chewed up from extended use. then (without disconnecting any spark plug wires) pull off the distributer cap and check the rotor (small plastic doohicky inside with a metal contact in the center and a flat tip that spins and contacts the underside of the cap) make sure it's not too chewed up. at this point you have covered the basics that could keep your rig from firing one day and not the next.
#6
Senior Member
Three things make an engine run , fuel , compression and spark . Check to make sure you have all three. If you are missing any of these get back to us with the specific problem and can help you from there by walking you through some simple steps to isolate the problem.
#7
I know I have compression I know I have fuel it's the spark that isn't there
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#8
Senior Member
Test the coil with an Ohm meter OR use a test light to see if the coil wire is pulsing while cranking. Pull the connector and test the DG/Y wire. It should pulse while cranking.
Note the other coil wire W/LB should have 12V power at all times when key is on.
If pulsing but no spark then the coil is bad.
If coil is good then pull the TFI module off of the distributor and have it tested at an autoparts store. You can buy the special Ford TFI removal tool at many autoparts stores for a few $
If TFI tests good then the problem is most likely the Hall sensor pickup inside the distributor. The sensor is hard to replace so most people just replace the whole distributor.
Note:You can buy the distributor with or without the TFI module.
If you buy a distributor you will most likely need the one with the cast iron gear.
Here is an ignition system diagram ('86 302):
http://imageshack.us/a/img809/943/50ignition.jpg
Note the other coil wire W/LB should have 12V power at all times when key is on.
If pulsing but no spark then the coil is bad.
If coil is good then pull the TFI module off of the distributor and have it tested at an autoparts store. You can buy the special Ford TFI removal tool at many autoparts stores for a few $
If TFI tests good then the problem is most likely the Hall sensor pickup inside the distributor. The sensor is hard to replace so most people just replace the whole distributor.
Note:You can buy the distributor with or without the TFI module.
If you buy a distributor you will most likely need the one with the cast iron gear.
Here is an ignition system diagram ('86 302):
http://imageshack.us/a/img809/943/50ignition.jpg
#10
Senior Member
Join Date: Apr 2013
Location: near Portland Oregon
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Pull the coil wire from the center of the distributor cap and hold the coil wire brass terminal 1/4" to 1/2" from the engine block where there is no paint. DO NOT HOLD THIS WIRE WITH BARE FINGERS. Now, have a friend crank the engine 1 or 2 revolutions and watch for white or blue sparks between the coil wire and the engine block. If the spark is red (weak) or nonexistent, replace the coil.
Last edited by DIY; 08-22-2013 at 03:12 PM.