Frustrated. No spark.
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New User
Joined: Oct 2018
Posts: 4
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Frustrated. No spark.
1986 F150 4.9 straight 6
82549 miles
4 speed manual with overdrive
mechanical fuel pump
dual tanks
new coil (has power in and out)
new plugs, wires
no power to distributor
am I missing a fuse or sensor
ran beautiful for 6 months then experienced loss of power, no spark since
any help is appreciated
driven in California
82549 miles
4 speed manual with overdrive
mechanical fuel pump
dual tanks
new coil (has power in and out)
new plugs, wires
no power to distributor
am I missing a fuse or sensor
ran beautiful for 6 months then experienced loss of power, no spark since
any help is appreciated
driven in California
Tuned
Joined: May 2013
Posts: 396
Likes: 5
From: Ottawa, Canada
First things first. Make you have good clean grounds between engine battery and body. Check fuses in the fuse panel. Then I'd check the wiring harness connections, then move onto the module...
Maybe you can check for power at the module with a multimeter.
Maybe you can check for power at the module with a multimeter.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
What do you mean by "No power at the distributor"?
Checked with a volt meter? The spark plugs aren't sparking?
Elaborate on that if you could please.
I have a guess though. My brother had this issue and it was extremely frustrating. Turned out it was the magnetic pickup inside the distributor.
The way it works:
As the engine spins, the shaft of the distributor passes the stator (the six armed star down underneath the rotor) passed the magnet. This signals that it's going by a spark plug post, and should fire.
That signal goes to the ignition control module, tells it to energize the coil.
The coil charges, and sends the spark into the distributor cap.
The charge goes through the cap, through the rotor, and to the spark plug post it's pointed at and off to the spark plug.
If your magnetic pickup fizzled, it won't get that signal, and your distributor will sit like a bump on a log.
Checked with a volt meter? The spark plugs aren't sparking?
Elaborate on that if you could please.
I have a guess though. My brother had this issue and it was extremely frustrating. Turned out it was the magnetic pickup inside the distributor.
The way it works:
As the engine spins, the shaft of the distributor passes the stator (the six armed star down underneath the rotor) passed the magnet. This signals that it's going by a spark plug post, and should fire.
That signal goes to the ignition control module, tells it to energize the coil.
The coil charges, and sends the spark into the distributor cap.
The charge goes through the cap, through the rotor, and to the spark plug post it's pointed at and off to the spark plug.
If your magnetic pickup fizzled, it won't get that signal, and your distributor will sit like a bump on a log.
New User
Joined: Nov 2018
Posts: 1
Likes: 0
85 loss of spark
I own a 85 300-6 that my dad and I rebuilt. It never ran great untill I really looked into that motor did it myself. Then I got all I could get with the running gears in it. Went along really good for a couple of years and then it started to die on me going down the road. Complete shut down. This became more regular and lasted longer every time until it was just done. No juice, wouldn't crank. After a few long days I got it to turn over but never would start. I spent a good month looking for the issue and never found it. What I had to do was take the ignition switch and mount it on out side of dash, install a basic ignition key switch off the shelf and wire direct through to starter off selinoid. Manually operate the ignition switch and use the key as a on off.
Lead Driver
Joined: Dec 2000
Posts: 6,293
Likes: 47
From: South central, Minnesota
1986 F150 4.9 straight 6
82549 miles
4 speed manual with overdrive
mechanical fuel pump
dual tanks
new coil (has power in and out)
new plugs, wires
no power to distributor
am I missing a fuse or sensor
ran beautiful for 6 months then experienced loss of power, no spark since
any help is appreciated
driven in California
82549 miles
4 speed manual with overdrive
mechanical fuel pump
dual tanks
new coil (has power in and out)
new plugs, wires
no power to distributor
am I missing a fuse or sensor
ran beautiful for 6 months then experienced loss of power, no spark since
any help is appreciated
driven in California
If you have a TFI ignition system no spark usually means a bad TFI ignition module, a bad coil or a bad computer. Since you said you are not getting power to the distributor I would suspect the computer. When they get old it's not uncommon for them to have capacitors burn up. But like the others have said check grounds, connectors etc. Also check for bad fusible links. I would suggest finding a good wiring diagram for your truck and use it with a multi-meter to chase down the issue. It can be very hard to diagnose a problem over the internet.
To tell if you have a TFI ignition system. Just take a look at the distributor. If it has a plastic ignition module bolted to the side of it and a distributor cap that is the same size as the distributor body. Then it's the TFI.
Elder User
Joined: Sep 2012
Posts: 505
Likes: 7
I'm not sure what no power to the distributor means either. Are you using an inline spark checker to look for spark? If that's what you're doing, and you see no spark, then take the cap off and turn the engine over by hand... make sure the distributor rotor is spinning.
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moodyfam9
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
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Dec 3, 2012 08:05 PM
