TV Shooter
Cadet
- Joined
- Sep 18, 2013
- Messages
- 7
http://forums.iboats.com/mercury-mariner-outboards/help-mercury-850-85-hp-issues-487181.html
Hi everyone! My 76' Mark Twain with a 76' Merc 850, is running very similar to a long winded thread referenced above that prompted me to post.
The motor and the boat and motor looked BRAND NEW when I bought it. New wiring harness, plugs, plug wires in 2013...Ran great on muffs.
First time out on the water, ran like a champ at idle and up to about 1/4 throttle, then just fell flat. I replaced the original metal tank, which was rusty. Replaced the tank-to-motor line and primer bulb and switched to the newer Merc tank quick disconnect (so I could run a newer tank right away). I also ditched the in-motor fuel filter and replaced it with an in-line just before the motor. Took 'er out. Same problem...
Frustrated and looking for answers, I pulled the airbox and drained the carb bulbs. Black rubber pieces and various detritus came pouring out when I reverse flushed with carb cleaner through the jets. Old fuel hoses giving up the ghost, I presumed. I just wanted to make sure the motor would do its motorly duties, so I threw her back together after a thorough carb douching, I thought I had the problem licked on the cheap. Took her out on my test loop, and BAH! More of the same, albeit at a little higher RPM. Just for sh*ts and giggles, while it was sputtering along, I pressed and held the choke button and BAM! She almost threw me out the back and took off like someone lit a JATO on my stern. Once up and on plane, she ran great! If I brought it back to idle, however, I would have to do the choke method to get going again.
In closing, carbs and fuel systems are the devil. I plan on replacing all hoses and clamps and overhauling the fuel pump in the coming weeks. After that, I'm leaving the carb rebuilds and link/sync in the hands of a local Merc mechanic familiar with these motors. I'm mechanically inclined, but to someone born in the 80's, carb tuning seems like hoodoovoodoo, something I'd rather have done right to eliminate my guess work. I was quoted $250 plus parts, done at my house, FYI.
Hi everyone! My 76' Mark Twain with a 76' Merc 850, is running very similar to a long winded thread referenced above that prompted me to post.
The motor and the boat and motor looked BRAND NEW when I bought it. New wiring harness, plugs, plug wires in 2013...Ran great on muffs.
First time out on the water, ran like a champ at idle and up to about 1/4 throttle, then just fell flat. I replaced the original metal tank, which was rusty. Replaced the tank-to-motor line and primer bulb and switched to the newer Merc tank quick disconnect (so I could run a newer tank right away). I also ditched the in-motor fuel filter and replaced it with an in-line just before the motor. Took 'er out. Same problem...
Frustrated and looking for answers, I pulled the airbox and drained the carb bulbs. Black rubber pieces and various detritus came pouring out when I reverse flushed with carb cleaner through the jets. Old fuel hoses giving up the ghost, I presumed. I just wanted to make sure the motor would do its motorly duties, so I threw her back together after a thorough carb douching, I thought I had the problem licked on the cheap. Took her out on my test loop, and BAH! More of the same, albeit at a little higher RPM. Just for sh*ts and giggles, while it was sputtering along, I pressed and held the choke button and BAM! She almost threw me out the back and took off like someone lit a JATO on my stern. Once up and on plane, she ran great! If I brought it back to idle, however, I would have to do the choke method to get going again.
In closing, carbs and fuel systems are the devil. I plan on replacing all hoses and clamps and overhauling the fuel pump in the coming weeks. After that, I'm leaving the carb rebuilds and link/sync in the hands of a local Merc mechanic familiar with these motors. I'm mechanically inclined, but to someone born in the 80's, carb tuning seems like hoodoovoodoo, something I'd rather have done right to eliminate my guess work. I was quoted $250 plus parts, done at my house, FYI.
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