mercury 200 20 hp won't keep running

[byronjacobson]

HI,
I acquired a 1975 200 20 hp mercury outboard that had a bad starter rope recoil. I repaired the recoil and can get the motor started, but it dies on me unless I keep spraying starter fluid into the carburator. I'm thinking the fuel pump diaphram needs replacing. I looked for a kit but can't find a source to buy it.
Do you guys think I'm on the right track or could it be something in the carburator. I took the carburator apart and cleaned it as well I could.
any advice would be appreciated. please send to jake331@charter.net or call me at 320-six -three -four-4919

 

[ONERCBOATER]

Re: mercury 200 20 hp won't keep running

1st take that can of starter fluid... and throw it away... save it for 4 strokes... but do not use it on your 2 stroke outboard... very bad juju. The starter fluid has no lubricant in it and ether has a very different pressure curve... not at all healthy for your engine if you like your engine STOP using starter fluid. In a pinch you can soak a portion of a clean rag with gasoline and cover carb intake with it so that the air only goes through one layer of gas soaked cloth, this will act as a carb and allow a choked cold start and then progressively lean out as the gas evaporates from the cloth. It will give you a fast safer indicator on if the issue with firing is a fuel problem or not, note I said safer not safe because there is no oil to provide lube this way either.
To check for fuel pump issue you can prime with primer bulb and then gently continue squeezing the primer bulb while engine running (your the fuel pump them) if this keeps engine running then your fuel pump is definitely suspect. My personal feeling is that this motor is new to you, and has been sitting a while, I would pull the carb, disassemble it, clean it very very thoroughly, NOT use welding tip cleaners to clean jets, keep the carb cleaner away from the plastic or cork parts (use dawn dish soap for them). Once you are very sure every lil part of the carb is clean, and all the passageways and holes are clean (I use hot tap water for this part as it gives me a visual that there is flow through the ports)... gently dry with compressed air and make sure you didn't leave water in there, reassemble with appropriate gaskets (new is strongly preferred but when in a hurry at the lake I have gotten away with reusing old gaskets but not recommended). Remount carb/fuel pump, connect fuel lines, prime with cover off to check for leaks, then set idle mixture screw to a richer then expected setting and proceed to start, then set for optimum operation and 1/8 to 1/4 turn richer than optimum.
I know it is a bit of work but this will get results. if you have other fuel issues.... after this, check for air bubbles in line via clear vinyl tubing replacing line to fuel pump. put proper fuel line back after you know there are no air bubbles. Speaking of fuel tubing, while you have carb off and out, replace the fuel tubing with new nifty alcohol resistant fuel tubing as the old stuff will cause you issues and plug up you nice shiny clean carb.

Sean

 

[byronjacobson]

Re: mercury 200 20 hp won't keep running

Hi,
You called me this morning and gave me a lot of good advice. After talking on the phone, i unscrewed the idle mixture screw, sprayed the inside orifice with carb cleaner, put it back together and the motor now runs fine. Apparently it had nothing to do with the fuel pump. I did order a fuel pump gasket set, and will have to decide whether to return it or keep it in case i need it later. cleaning the idle mixture jet was easy as i didn't have to disassembly anything. the screw is easily accessable from the front.

Sean, thanks again for you help. It felt good to get the motor started. Now all I have to do is find a buyer for it and also fix the front cover latch assembly. Again thanks.