Fuel problem on 1975 4hp johnson

[vanman1]

Hi, new to this forum but a big thanks for all the info ive read so far this place is great!!
Ok bear with me iam not a machanic
ive just aquired a second hand outboard model no:4br75a serial no:b17839.
1st... am i right in thinking this is a 1975 4hp?
2nd.ive got i think a fuel /carb problem ,engine will fire and run on full choke but then dies after about 10 seconds.If i put choke in its a total no go at all.
spray easy start into carb fires/runs straight away but dies after its burnt off.Carb bowl is full of petrol at all times.
It seems to me the fuel is not getting through from the carb?ANY HELP PLEASE ITS DRIVING ME NUTS
Would cleaning /fitting a carb re-build kit do the trick? if so can someone post a link to the correct kit i need please iam not sure what to buy.Also will i get a new float with this kit.
Many Many thanks in advance for any help recieved if i can sort the fuel problem il have a nice engine!

 

[tashasdaddy]

Re: Fuel problem on 1975 4hp johnson

1975 4hp, made in Belgium, sure sounds like a varnished up, dirty carb.

you have to adjustable jets, so you will not need the special tool mentioned here. http://forums.iboats.com/showthread.php?t=244013

this is your correct kit for the carb, even though it does not say so.
http://www.iboats.com/mall/partfind...=1310&gd_partfinder=1&gd_poid=109333&gd_row=4

after rebuild use these directions:

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle va /lve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[vanman1]

Re: Fuel problem on 1975 4hp johnson

Oh man you just made my day,so i was on the right track then?A clean and carb re-fit should solve the problem?
Are these kits easy to fit?i pressume i just fit the kit then follow your instructions for settings etc.
Many thanks

 

[tashasdaddy]

Re: Fuel problem on 1975 4hp johnson

pretty much, it will come with all kinds of parts, and o rings. the round metal disc can be removed with a ice pick, just punch thru enough to pry the disc out, then to install new ones, i use a small wooden dowel, and hammer and just tap them in so they are tight. you may not need all the parts, as it is packaged for several carbs. besure to replace the seals on the jets stems. insert them into the carb, then thread the stems into them, and the carb.