I friend gave me a 1978 4.5hp Mercury. He purchased it new back in 1978. After putting it in storage 5 years ago and said he just couldn't get it running right and ended up getting a yamaha 9.9 4 stroke fall in his lap for 400 bucks. Before I even tired to fire it up I notice that positive wire from the coil to the stator was completely corroded, i barely touched and it broke into. I replaced that wire. I then tried to start and it started fairly quickly, but it only starts at full throttle and it revs up to very high RPMs for a second or three and then it starts to die.. Sometimes it doesn't die, revs up again, repeats this process and then shuts down.
I'm not motor mechanic, but enjoy tinkering so I took the carb apart and cleaned it completely, 100% sure all orfaces were clear, but had one problem thats bothering me. i was not able to remove the main nozzle, part number 29 at this link http://www.crowleymarine.com/mercury-outboard/parts/681_4.cfm , completely as the head where you unscrew it appears to have been damaged. if I had to guess, someone probably tried to remove it by unscrewing and the brass just chipped away on on side. I'm not sure how critical this piece is???? I just cleaned it with a small wire like the other jets, and put the carb back together with gaskets. While i was at it, i replaced all gas hoses, spark plug, impeller (water flows great from tale tell whatever you guys call it), and lower unit lube before attempting to start it again..
After doing all this, the motor still runs exactly the same, maybe a hair bit better, but still only starts at full throttle, revs up and down, and then dies.. It will not start at idle and will not run at idle period. After searching these forums it seemed to be starving of fuel, so I thought maybe the float/needle might have been sticking or the fuel pump was bad. I removed the housing that holds the needle, seat, and filter. The first thing i checked was the needle and seat and it has no issues moving freely, it does not stick. Next i pumped my bulb on the gas tank and gas flowed like crazy thru the needle/seat as i assume it should, so this leads me to believe the fuel pump is good? I then adjusted the levels that the float actuates so allow a bit more gas to stay in the bowl, tried to start it up, and it ran the same as before. I'm positive there is plenty of fuel in the bowl. I'm concerned that my issue may be the main nozzle (part number 29 mentioned above).. Heck, I don't?? Part number 22, i think its called a jet, slides right into the main nozzle/part number 29.Any advice would be appreciated.
I'll add that I have spent days on every forum I can find searching for answers, but this is my first post. In many post I notice folks ask for help, get a lot of great advice, but they never return to the forum to share what they did to get it going. If I get this baby running right, I promise to share the end result! I'm loving the challenge, but I'm getting frustrated at the same time.
P.S.. i'm trying to upload some .jpg photos, but its failing for some reason. jpgs are about 1mg in size.
I'm not motor mechanic, but enjoy tinkering so I took the carb apart and cleaned it completely, 100% sure all orfaces were clear, but had one problem thats bothering me. i was not able to remove the main nozzle, part number 29 at this link http://www.crowleymarine.com/mercury-outboard/parts/681_4.cfm , completely as the head where you unscrew it appears to have been damaged. if I had to guess, someone probably tried to remove it by unscrewing and the brass just chipped away on on side. I'm not sure how critical this piece is???? I just cleaned it with a small wire like the other jets, and put the carb back together with gaskets. While i was at it, i replaced all gas hoses, spark plug, impeller (water flows great from tale tell whatever you guys call it), and lower unit lube before attempting to start it again..
After doing all this, the motor still runs exactly the same, maybe a hair bit better, but still only starts at full throttle, revs up and down, and then dies.. It will not start at idle and will not run at idle period. After searching these forums it seemed to be starving of fuel, so I thought maybe the float/needle might have been sticking or the fuel pump was bad. I removed the housing that holds the needle, seat, and filter. The first thing i checked was the needle and seat and it has no issues moving freely, it does not stick. Next i pumped my bulb on the gas tank and gas flowed like crazy thru the needle/seat as i assume it should, so this leads me to believe the fuel pump is good? I then adjusted the levels that the float actuates so allow a bit more gas to stay in the bowl, tried to start it up, and it ran the same as before. I'm positive there is plenty of fuel in the bowl. I'm concerned that my issue may be the main nozzle (part number 29 mentioned above).. Heck, I don't?? Part number 22, i think its called a jet, slides right into the main nozzle/part number 29.Any advice would be appreciated.
I'll add that I have spent days on every forum I can find searching for answers, but this is my first post. In many post I notice folks ask for help, get a lot of great advice, but they never return to the forum to share what they did to get it going. If I get this baby running right, I promise to share the end result! I'm loving the challenge, but I'm getting frustrated at the same time.
P.S.. i'm trying to upload some .jpg photos, but its failing for some reason. jpgs are about 1mg in size.