truck wont start
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truck wont start
my truck has decided that it dont want to run now.its not getting spark.i replaced the coil...didn't help....i replaced the brain....didnt help.....replaced ignition switch...thats not it.what is funny is that when you let off the key it will spark once.i had a screwdriver in the plug wire and every once in awhile it will throw multipal sparks....anybody have any ideas.
the truck is a 78'f100 with a 302 and auto. tranny.its 2wd.
the truck is a 78'f100 with a 302 and auto. tranny.its 2wd.
Last edited by hotrodf100; Sep 3, 2006 at 03:19 PM.
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Pickup module in distributor.
Here is a word of advice.
Just don't throw new parts at the truck.
Troubleshoot ....and we're here to help.
It could be as simple as a broken wire
or
a bad round on the ECM
What tests did you do to determine the "No Spark condition "?
You can test a coil for free. (grab your muliti-meter)
You can test a ECM for free at you local parts store (but having a spare one in the truck is good to do)
You can do a simple Pick-up Module test for free.
Does the distributor rotor turn when the engine cranks?
From another thread like this topic:
Here is a word of advice.
Just don't throw new parts at the truck.
Troubleshoot ....and we're here to help.
It could be as simple as a broken wire
or
a bad round on the ECM
What tests did you do to determine the "No Spark condition "?
You can test a coil for free. (grab your muliti-meter)
You can test a ECM for free at you local parts store (but having a spare one in the truck is good to do)
You can do a simple Pick-up Module test for free.
Does the distributor rotor turn when the engine cranks?
From another thread like this topic:
Originally Posted by banjopicker66
This can be very frustrating, I know. Been there, done that, wore out more than a few T-shirts doing it.
All right, try these:
1. Can you double check that the collar on the coil is correctly installed? I don't think it is possible to install it backwards, but one never knows. Make sure the BAT side is truly on the battery side of the coil; it should be marked. Make sure the contacts are fully and properly engaged.
2. Can you check the ground? On the 4 wire connector at the brain box, on the back side of the connector (that is, between the connector and the box), you should have continuity between that wire and ground. This black wire grounds through the distributor. If not, then double check grounds between the distributor and the block, block and frame, block and cab/sheet metal, frame and cab/sheet metal.
3. Did you take the tach off just to make sure it isn't fouling things up somehow?
4. Use a jumper wire from the battery to send a full 12 volts to the wires below.
First, on the 2 wire connector at the brain box, jumper 12 volts from the battery to the RED wire coming out of the box (between the box and the connector). With the 12 V jumpered, see if you get spark. (I often use a sewing pin to pierce the wire, and then hook to it an alligator clip.)
If you do, then jumper the 12V to the other side of the connector, and try again to check the electrical connectivity of the connectors.
Second, if you do not get spark, ADD another 12V jumper to the BAT side of the coil, and try again.
If you finally get spark, then you have some power supply problems somewhere.
If these don't work, post back. I am hoping this test will reveal that although you may have voltage to the right spots, it may not be enough, or provide enough amperage.
.
All right, try these:
1. Can you double check that the collar on the coil is correctly installed? I don't think it is possible to install it backwards, but one never knows. Make sure the BAT side is truly on the battery side of the coil; it should be marked. Make sure the contacts are fully and properly engaged.
2. Can you check the ground? On the 4 wire connector at the brain box, on the back side of the connector (that is, between the connector and the box), you should have continuity between that wire and ground. This black wire grounds through the distributor. If not, then double check grounds between the distributor and the block, block and frame, block and cab/sheet metal, frame and cab/sheet metal.
3. Did you take the tach off just to make sure it isn't fouling things up somehow?
4. Use a jumper wire from the battery to send a full 12 volts to the wires below.
First, on the 2 wire connector at the brain box, jumper 12 volts from the battery to the RED wire coming out of the box (between the box and the connector). With the 12 V jumpered, see if you get spark. (I often use a sewing pin to pierce the wire, and then hook to it an alligator clip.)
If you do, then jumper the 12V to the other side of the connector, and try again to check the electrical connectivity of the connectors.
Second, if you do not get spark, ADD another 12V jumper to the BAT side of the coil, and try again.
If you finally get spark, then you have some power supply problems somewhere.
If these don't work, post back. I am hoping this test will reveal that although you may have voltage to the right spots, it may not be enough, or provide enough amperage.
.
Last edited by Mil1ion; Sep 3, 2006 at 03:46 PM.
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done all this.installed a new pick up in the dis.i worked my way through every possible thing i could think of starting with the coil,then the ignition mod.,then the ignition switch,then the pick up.i check every wire between the dis to the ign. switch. i have no idea whats going on.sometimes it gets very little spark other times no spark at all and as soon as you quit turning it over it'll spark once.i don't make sence.
