no spark, some cylinders.

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Dec 17, 2000 | 08:23 AM

Truckasoras

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no spark, some cylinders.

Hello all. I have, as tested with a inductive timing light, steady spark on several cylinders, such as #4, 7, but no spark or occasional spark on #1, 6 etc. Always the same cylinders fire OK and the same have problems. I have: new distributor,plugs, (and swapped them around), wires (and swapped them around), cap, good coil, ignition mod. Will not idle, or even start sometimes. 2 questions: Will the timing light fire if the plug is bad?, What would make a new plug bad? I am wondering if something in the ignition system is 'breaking' the plugs. Thanks. Larry

Dec 17, 2000 | 11:24 AM

shawnb

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no spark, some cylinders.

[font size="1" color="#FF0000"]LAST EDITED ON 17-Dec-00 AT 12:36 PM (EST)[/font][p] Did you replace all these parts because of the missing cylinders? An inductive timing light will flash every time a current is passed down the wire it is attached to. Spark plugs are designed to take tens of thousands of volts constantly, so I do not think that your system is breaking them. Have you put your timing light on the coil wire? If that shows a consistent spark then something in you distributor is not sending spark to certain wires. If the coil wire is not getting consistent spark then recheck your coil. Good luck.

Dec 17, 2000 | 04:01 PM

Truckasoras

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no spark, some cylinders.

All of the electrical system checks! I just noticed that the plugs are getting VERY blackened with carbon in a short period of time. Also the engine will only start with the pedal floored and I've gone thru 5 gallons of fuel without leaving the drive!. When I managed to get the engine up to operating temp it started backfiring in exhaust and thru the carb. Sound like its running rich? Timing? I have had to approximate the timing as the marks on the pulley are so bad from rust that I can only see where they start and end, so I timed it to the mid point, which I think is about 8btdc based on diagrams I've seen of the marks. Assuming it's rich for some reason what besides the idle screws is reccomended. I have the motocraft 2150.

Dec 17, 2000 | 04:48 PM

Nathan

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no spark, some cylinders.

Check to see if your float is sticking open, drowning the cylinders when you shut it off.

Nathan

Dec 17, 2000 | 05:48 PM

thelonerangerxlt

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no spark, some cylinders.

Truckasaurus, try running a jumper wire directly from battery + to + side of coil and see if engine runs better. If it does, then look backwards to ignition switch. If it runs the same, at least you've isolated it to the coil forward. Good luck. Don

"Nothing lasts forever except natural stone and old Ford trucks." (Willie Nelson)

Dec 20, 2000 | 11:02 AM

Chuck P.

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From: SE PA

no spark, some cylinders.

If all else comes up good, check or replace the voltage regulator on the pass. side fender, these are known to cause some interesting "problems" when they go. Last one I got was around 10-12 bucks.

Mar 26, 2001 | 11:50 AM

jcf250custom

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no spark, some cylinders.

hey, pull your distributor, your timing is all thrown off, my 79 f250 with a 351m, did the exact same thing, I replaced the ignition box, stator, wires , coil, I had NO power , the truck wouldn't even budge, and I had to floor it to start it up, and after that even in neutral, it wouldn't even go above 2000 rpm when I floored it!I finally replaced the dist, and kept pulling it and advancing the timing till I had power, some how the gear on the dist jumped. Find where your timings at,then try pulling the dist.