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'84 Mariner 8hp Won't Idle

Rupert28

New member
I have a 1984 8hp, manual start, and I can't get it to idle without pumping the choke. I can however, run it at high RPM with very minor sputtering. It seems to me that it's not getting enough fuel for some reason. I have taken apart the carb part way, sprayed out the high and low speed jets with carb cleaner, and cleaned everything I can. Upon re-installation, I still encounter the same problem. I am stumped! Any ideas about what to try next?
 
I checked the diaphragm in the fuel pump, but it all seems to be tight with no holes. Since then too I have replaced the spark plugs, and run engine cleaner through the fuel. However I still encounter the same problem- no idle! Any other ideas?
 
clogged fuel filter at tank...
carbs need a full rebuild...
poor compression...
is this a sudden problem or something that has been happening and is now worse?
 
This is something that happened all of a sudden. It seems like last year it was running fine, with minor problems while throttling down toward the end of the year. I put some fuel stabilizer in at the end of the year, and went to try it this spring with no chance of an idle.

No clogged filters at all, recently rebuilt the entire carb.

On that note, what would I do to test/fix compression issues?
 
to test the compression, get a compression guage, (or borrow one if you have a friendly mechanic). remove spark plug, install guage into same hole, crank the engine 4 or so times, check reading. Should be between 120ish to 150 ish, repeat until all pistons are done. All readings should be close to the same.
make sure you disconnect the gas line also.
 
I think my compression is okay, given that I have no problem making the engine run anywhere from half throttle on up. I have done some additional research however, and have concluded that it possibly could be a valve adjustment problem. Does anyone know what the valve measurements are for this motor? Serial #8M 6G1 S 013037
 
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