ALMOST THERE! Now Im stuck on the Carb!

[Puzzled look]

Hi

Ive been having problems with my engine 1976 Mercury 200 (20 HP). It ran ok but needed about 1/4 choke constantly out to run. Carb problems I thought. So I set about stripping the carb down and found it to be full of crap! I have since cleaned it and replaced every gasket and the float with new ones. Ive put it all back together and started it up. Problem solved the I dont need the choke to run it only to start it!!

The problem now is I cant get it to Idle and when it runs at high revs it keeps missing. What could this be Im a novice so Im really stuck.

Ive adjusted the idle screw but assume this is for fine adjustments and i think i have something bigger on my hands.

The other burning question is there is another screw on my carb on the right hand side What is this?? I have tried to take it out but it is stuck could this be the cause?

 

[Puzzled look]

Re: ALMOST THERE! Now Im stuck on the Carb!

Slight amendment it seems to run ok at hight revs infact its ok in the top two thirds of the throttle range, its just the lower third when it cuts out.

 

[Laddies]

Re: ALMOST THERE! Now Im stuck on the Carb!

Did you clean the idle pickup tube?

 

[Puzzled look]

Re: ALMOST THERE! Now Im stuck on the Carb!

sorry to sound dumb but which one is that?

 

[backyard mechanic]

Re: ALMOST THERE! Now Im stuck on the Carb!

The idle pick up is the one that sticks up in the center of the carb throat. You have bigger fish to fry... You had crap in your carbs but did you do anything about the fuel tank, fuel pump or filters? I'd be looking into that as your problem and perhaps now the carbs are dirty again if you neglected to do anything about the tank back. From your explaination, I'd say you had a fuel pump/delivery problem. If your carbs were dirty so will your fuel pump and system be dirty.

As for the screw in the side of the carb... Fast idle jet is inside. Not able to be set.

Once all that stuff is set, be sure to sync the carbs with your timing. Your manual will show you how.

 

[Puzzled look]

Re: ALMOST THERE! Now Im stuck on the Carb!

Thanks, When I bought the engine a few months a go it came with its original fuel tank. I checked this straight away and found it to be corroded. I binned it and bought a new plastic one. I also dismantled the fuel lines and blew them all through with the air gun. I should have mentioned that when I also stripped the carb down I also did the fuel pump as well so it has a new diaphram and gaskets and filter.

Ive just stripped everything down again to check again that everything is clean and blew out every hole possible!.....no joy the same problem.

I also had trouble starting it and noticed fuel pouring out of the carb as i pulled the cord so I know it has a good draw on it. On inspecting the plugs I found them to be fouled I cleaned these and it started Ok but still with the same problem wont idle and occasionally miss fires at mid throttle. Could the plugs provide a clue?

Its weird how it ran reasonably well with the carb full of crap but wont when its clean.

 

[Puzzled look]

Re: ALMOST THERE! Now Im stuck on the Carb!

Ive read in manuel about a pinhole in the diaphragm causing wet foul to the plugs at low rpm, my plugs are fouling. I've inspected the diaphragm and cant see any pin holes, just to be sure I put the old one back on....no change.

Arrrgh im tearing my hair out!!!!!