Cylinders 1,3,5,7 Have Spark But dont appear to be firing.

L

LutzCoyote

Member
Good Evening,
I have a 72 Scout II with a 304 motor and have noticed what seems some like some lack of power. In doing some checking I get spark to all the plugs but while running If I pull a plug wire from the even cylinders, I notice the running engine changes which I would expect however, if I pull the plug wire from any of the odd cylinders there's no change to the engine. Does this mean those cylinders aren't firing because i'm not getting fuel, a valve or cam bearing issue?
Just as a FYI, I replaced the plugs and still have the same result.

Thanks In advance for any suggestions of if there's any additional information I can provide.

Sam
 
The symptoms described sound like a plugged idle circuit. Try a shot of carb cleaner down each barrel of the carb. My guess is that the rpm's will pick up on one side or the other. Let us know your results.
 
FDChappie said:
The symptoms described sound like a plugged idle circuit. Try a shot of carb cleaner down each barrel of the carb. My guess is that the rpm's will pick up on one side or the other. Let us know your results.
Click to expand...
Thanks FDC, I'll try that today and update. FYI, I have a new Holley 2300 I put on about a year ago.
 
I've found water in the fuel will do it to my Holley carbs. Although it's a lot better since they got rid of the MTBE.
 
Solved the the proresponse. I tried the carb cleaner as you suggested with no noticing change.
Turns out the place I hired to do some work on the truck, which included new plugs put in plugs that were too long.
I pulled a few and the ones that were fully tightened were hitting the piston and closed the gap. The ones that were working weren't fully seated.
Replaced them all with correct size and now it runs like a champ.
Thanks again for your respones.
Sam
 
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