Intermittent problem with 4.9
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Intermittent problem with 4.9
I have a 95' F150 with the 300 straight 6. I use the truck to commute to work, so I put a lot of miles on it. Lately I have been having issues with the truck randomly quitting on me. No sputtering or otherwise abnormal running, it just dies. I get a CEL when it does. Sometimes it will start right up, sometimes it won't. When it quit last time, I turned the key on and heard the fuel pump humming. So I'm assuming it's not a fuel issue. Another time, the truck would not re-start. I popped the hood and made sure the wires to the coil and distributer were hooked up. After unplugging the wire to the coil and plugging it back in, it started. I thought maybe it was a coil problem so I replaced it. The truck still quits though..can someone with more troubleshooting experience lead me in the right direction here? It's so intermittent, it's hard to do any troubleshooting. Especially since the last two times it's done it has been in Houston traffic. If y'all have any questions on the truck ask away. Thanks for any help
Post Fiend
Joined: Oct 2009
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From: town of less than 200 ppl
I would first look at the ignition module, and then the PIP.
If I understand it correctly, if it will restart with the snout unplugged, that points to a bad PIP. Do some research, there is mountains of information located at this site.
Edit:
Look at that, I was bored and did some leg work for you..
http://easyautodiagnostics.com/ford/...module-tests-1
*hint hint* click the link ^
Edit: You may also find this interesting...
http://www.f150online.com/forums/pre...m-95-f150.html
If I understand it correctly, if it will restart with the snout unplugged, that points to a bad PIP. Do some research, there is mountains of information located at this site.
Edit:
Look at that, I was bored and did some leg work for you..
http://easyautodiagnostics.com/ford/...module-tests-1
*hint hint* click the link ^
Edit: You may also find this interesting...
http://www.f150online.com/forums/pre...m-95-f150.html
Thread Starter
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Senior User
Joined: Apr 2012
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Thanks for the input guys. I just read through the above links, now I'm gonna go see what I can find on the truck. I figure I'll check the harness from the distributer to ICM first and go from there.
Fleet Owner
Joined: Oct 2005
Posts: 20,785
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From: Kentucky
The SPOUT has no direct interaction with the PIP signal. By removing the SPOUT (Spark Out) you are removing the computer (PCM) from the equation. In this scenario the Ignition Control Module (ICM) is getting the raw/unbuffered signal from the PIP, the computer no longer has control.
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Cargo Master
Joined: Mar 2007
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From: Arcadia, Fla
With a intermittent problem its going to be hard to find. I had the same issue with my 89 F250 cold turkey quitting on me.
One thing that helped me out is I had a tachometer and every time the problem showed up, the tach would drop to 0 RPM. That meant it was electrical issue. It took me ALMOST a year to track the intermittent problem down. Problem only happened once in a few weeks to months. No amount of wire wiggling would cause the problem too.
I finally found my problem when it "hard faulted". It was the ECU power relay was going bad. When you cycled the ignition switch, the relay would make good contact and engine would run till the relay's contact would open up shutting down the engine.
One thing that helped me out is I had a tachometer and every time the problem showed up, the tach would drop to 0 RPM. That meant it was electrical issue. It took me ALMOST a year to track the intermittent problem down. Problem only happened once in a few weeks to months. No amount of wire wiggling would cause the problem too.
I finally found my problem when it "hard faulted". It was the ECU power relay was going bad. When you cycled the ignition switch, the relay would make good contact and engine would run till the relay's contact would open up shutting down the engine.
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I had a similar issue with my truck (1990 f150 4.9 5 speed) it would randomly shut off while driving and wouldn't start 25% of the time. It's the reason my grandfather sold me the truck, his mechanic told him to junk it.. (Junk a 4.9??) It turned out to be the plug going into the coil was corroded and making a bad connection along with a few other plugs that I can't remember. I found the problem by getting under the good, grabbing wires and shaking them while the truck was idling. I found my issue when the truck quit by shaking the coil wires. Solved it with some contact cleaner and dielectric grease. Driving for almost 2 years now and the truck hasn't died on me since (except when I run out of gas, but that's my own fault)
Post Fiend
Joined: Oct 2009
Posts: 8,674
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From: town of less than 200 ppl
Wrong.....
The SPOUT has no direct interaction with the PIP signal. By removing the SPOUT (Spark Out) you are removing the computer (PCM) from the equation. In this scenario the Ignition Control Module (ICM) is getting the raw/unbuffered signal from the PIP, the computer no longer has control.
The SPOUT has no direct interaction with the PIP signal. By removing the SPOUT (Spark Out) you are removing the computer (PCM) from the equation. In this scenario the Ignition Control Module (ICM) is getting the raw/unbuffered signal from the PIP, the computer no longer has control.
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