48 8n starts hard and barely runs

flembo

Well-known Member
I am watching a similar thread that sounds similar. This tractor has always been a quick starter and always ran great. I parked it the beginning of April and it sat until July when It refused to start. A spark check showed no spark its been 5 or 6 years since points and plugs were changed so I pulled the distributor and dressed the points that, didn't look to bad I also used Dellwa advise and pulled a dollar bill thru to remove any dirt. It started and ran well so I parked it again. Now October its a no start I I checked gas flow thru carb filling a pint jar in less than 2 minutes. A spark check showed a very week spark Voltage at coil showed 6.4 v and changed back and forth from 6 to about 3 as it cranked. I replaced the points with bluestreak and set gap to .015 and timing per fo4. Now good spark jumps ,187 gap and it starts fast but runs terrible backfiring thru carb and exhaust just barely running. I am not one to just throw parts at it but I decided to try one thing at a time, I have several new parts sitting on the shelf so I tried a new 6 volt coil with no change so then I tried a new cap again no change I even tried a new rotor with no change. my last try was a temporary set of solid core wires tie wrapped to the the tube with no change. Could a bad condenser cause this. I haven't checked compression. The gas looked clean after the flow check thru carb. { I check spark with an old plug set to 3/16"} Any advice is welcomed I am at wits end. Oh Dell wa always said a quick 2 bolt 5 minute job unsnaple the caple and let er dangle. Not for me.
 
I am watching a similar thread that sounds similar. This tractor has always been a quick starter and always ran great. I parked it the beginning of April and it sat until July when It refused to start. A spark check showed no spark its been 5 or 6 years since points and plugs were changed so I pulled the distributor and dressed the points that, didn't look to bad I also used Dellwa advise and pulled a dollar bill thru to remove any dirt. It started and ran well so I parked it again. Now October its a no start I I checked gas flow thru carb filling a pint jar in less than 2 minutes. A spark check showed a very week spark Voltage at coil showed 6.4 v and changed back and forth from 6 to about 3 as it cranked. I replaced the points with bluestreak and set gap to .015 and timing per fo4. Now good spark jumps ,187 gap and it starts fast but runs terrible backfiring thru carb and exhaust just barely running. I am not one to just throw parts at it but I decided to try one thing at a time, I have several new parts sitting on the shelf so I tried a new 6 volt coil with no change so then I tried a new cap again no change I even tried a new rotor with no change. my last try was a temporary set of solid core wires tie wrapped to the the tube with no change. Could a bad condenser cause this. I haven't checked compression. The gas looked clean after the flow check thru carb. { I check spark with an old plug set to 3/16"} Any advice is welcomed I am at wits end. Oh Dell wa always said a quick 2 bolt 5 minute job unsnaple the caple and let er dangle. Not for me.
 
Sure sounds like the classic "firing order 1-2-4-3 was not followed in cap/wires replacement."
 
If you still have a weak spark clean the points. Many new points have a protective coating on them that needs cleaned off
"....and changed back and forth from 6 to about 3 as it cranked."....sure sounds like points are switching to me!
 
Along with possible firing order mix up, just because fuel runs clear and steady from the carb bowl drain does not mean there isn't a blocked passage inside the carb.
 
Along with possible firing order mix up, just because fuel runs clear and steady from the carb bowl drain does not mean there isn't a blocked passage inside the carb.
That reminds me if it means anything I pulled the choke out all the way while it was running lousy and it didn't have any affect. I also pulled a wire of each plug 1 at a time and restarted it and it ran the same. I attached my sparktest plug to each plug while running and watched to see if spark was intermittent. sometimes I thought it was but couldn't be sure I think I will check again.
 
If you still have a weak spark clean the points. Many new points have a protective coating on them that needs cleaned off
I have a nice blue spark jumping 3/16" I can't adjust the plug to 1/4'' as you suggest in the past. BTW I do read your post and enjoy them. keep them coming.
 
That reminds me if it means anything I pulled the choke out all the way while it was running lousy and it didn't have any affect. I also pulled a wire of each plug 1 at a time and restarted it and it ran the same. I attached my sparktest plug to each plug while running and watched to see if spark was intermittent. sometimes I thought it was but couldn't be sure I think I will check again.
I always thought it best to pull a plug wire when running and see if the engine drops when the wire is pulled. Loosen the wires first, start, then use a pair of fuse puller pliers (or other well insulated pliers, to lift the wires off the plugs. That way you can tell better if the cylinder makes a change or not.
 
I have a nice blue spark jumping 3/16" I can't adjust the plug to 1/4'' as you suggest in the past. BTW I do read your post and enjoy them. keep them coming.
Okay if you have a good spark pull the carb air tube off and hold you hand over he air intake of the carb and try to start it. You should get a good suction and gas on your hand and it may even start. I've done that many ties and doing so can clear a small clog in the carb
 

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