No spark problem
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Joined: Aug 2013
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No spark problem
hello been reading ur guys posts I have a somewhat same issue but im getting no spark what so ever, I have a 1985 F250 TDI engine 4.9L 300, I have replaced everything in the ignition system but the engine wire harness, I have inspected all the wiring harness from the computer and ignition switch to the battery, voltage regulator, and distributor. and I have replaced the computer with a reman one, plz I am that a lost to figure out what is wrong, any help would be amazing
Postmaster
Joined: Feb 2011
Posts: 3,560
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lets start with the cheap and simple tests...
1) remove distributor cap, crank engine, verify that the rotor is turning. if it isn't, remove distributor and diagnose further.
2) as dave said, check for power to + side of coil
FWIW, i'm the kind of guy who likes to test 20 things and replace 1, not the kind who likes to replace 20 things until 1 solves the problem.
1) remove distributor cap, crank engine, verify that the rotor is turning. if it isn't, remove distributor and diagnose further.
2) as dave said, check for power to + side of coil
FWIW, i'm the kind of guy who likes to test 20 things and replace 1, not the kind who likes to replace 20 things until 1 solves the problem.
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New User
Joined: Aug 2013
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ok srry its been awhile since I have gotten back, the rotor and distributor do spin when I crank the engine, and I have tested the + on the coil with the power on and I got power, so what will be my next step
Postmaster
Joined: Feb 2011
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next step will be to put your test light across the + and - terminals of the coil. on a properly functioning system, your test light will flash while the engine is cranking.
if your light does flash for that test, then you have proper signal into your coil. if this is your case and the coil doesn't send a spark, then you have a bad coil.
if the light doesn't flash in that test, then your distributor isn't sending the signal to tell it to spark. the problem may be with the pickup unit inside the distributor, or with the module screwed onto its side, or with related wiring. the modules seem to be the most common failure, so i would suggest taking the module into your local auto parts store and ask them to test it for you. note that the module is best removed with a special wrench made for the purpose, which is available at most auto parts stores.
if your light does flash for that test, then you have proper signal into your coil. if this is your case and the coil doesn't send a spark, then you have a bad coil.
if the light doesn't flash in that test, then your distributor isn't sending the signal to tell it to spark. the problem may be with the pickup unit inside the distributor, or with the module screwed onto its side, or with related wiring. the modules seem to be the most common failure, so i would suggest taking the module into your local auto parts store and ask them to test it for you. note that the module is best removed with a special wrench made for the purpose, which is available at most auto parts stores.
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
I will explain how to fix the spark problem..Disable the fuel system by removing the fuel pump fuse or relay.Remove the spark plug wires one at a time and insert a small screw driver into the wire.Remove the distributor cap.Turn the ignition key on but don't crank the engine.Locate the negative or ground wire attached to the engine coil.Have someone crank the engine while watching the test light.heck the pulse generator in the distributor if it has a distributor cap.With the engine in non-running condition connect your A/C voltmeter to the pair of wires at the pulse generator and crank the engine.Know that if this part of the primary ignition tests OK then check wiring to ECM pinouts for opens.
How to Diagnose a Loss of Spark in Your Car Engine: 9 Steps
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