Old Merc won't work

[Willard]

My 1964 3.9hp Merc will only run if I squirt fuel in the cylinder through the spark plug hole. It has a fixed high speed jet and the idle is set 1.5 turns out. I replaced both reed valves. These are fixed . No reed stops. I replaced the needle and seat in the carb also. Thanks in advance for any help.
Willard

 

[AMD Rules]

Re: Old Merc won't work

Check your fuel pump. Will it run if you pump the fuel bulb by hand?

Is the float in the carb adjusted properly, to allow fuel to pass the needle/seat when required?

 

[Laddies]

Re: Old Merc won't work

Once and awhile the lowspeed pickup tube in the carb will plugup and cause a problem on starting

 

[cnadianut]

Re: Old Merc won't work

Hey i had the exact same problem. Some one gave me a 1972 cutter with a 1969 merc 800 on the back. Same thing, i shot some gas in the cylinder and it started. So i had my upper carb and fuel pump rebuilt. Now i still have problems when i start it if the engine is cold. I got a bottle of quick start and give my upper carb a good shot of it, fully accelerate the idle arm and it starts every time. Kind of a pain in the butt, but it works. Oh and be ready to get off the idle arm it will scare the crap out of others on the dock when that old lady starts screaming.
Ran her for about 4 hours straight yesterday, I Love granny merc d

 

[Deep_Blue]

Re: Old Merc won't work

One easy test (and I love this one). At night get a really bright and small flashlight, crank the engine at wide-open throttle with the lanyard switch off! Hold the flash light right up to the mouth of the carb and look for the jetting of fuel. It’s really easy to see (even with high speed misting)!

 

[Caddy_Kid]

Re: Old Merc won't work

Had the same thing happen last week with my 2hp Honda. It has a gravity fuel pump, so I didnt have to worry about that. It would start with a spray of starting fluid but would die after it burned that up. There was great spark and the plug even came out of the motor wet after several good pulls.

Took the carb off the motor and completly apart (float, needle, bowl, main jet, etc all came off) and soaked the metal parts overnight in laquer thinner. When I took the main jet out of the carb, it was literly plugged solid. After soaking it and everything else overnight, I ran compressed air through all the little passages that I could see. Put it all back togeather and it started second pull and runs great. You may have already done all this, since you replaced the needle, but thought I would at least add it.

I rebuilt the three carbs and fuel pumps on my Merc 1000 recently and the new needles that they gave me required alot of tweeking once I got them in so that they opened and closed the correct ammount according to the instructions. The needles were fine, but the two open and close levers that the float activates needed to be tuned up quite a bit so that they all worked properly. Apparently the needles that they gave with the rebuild kits were a bit longer than the origional ones. Just a thought if you hadnt done that yet!

 

[Willard]

Re: Old Merc won't work

Had the same thing happen last week with my 2hp Honda. It has a gravity fuel pump, so I didnt have to worry about that. It would start with a spray of starting fluid but would die after it burned that up. There was great spark and the plug even came out of the motor wet after several good pulls.

Took the carb off the motor and completly apart (float, needle, bowl, main jet, etc all came off) and soaked the metal parts overnight in laquer thinner. When I took the main jet out of the carb, it was literly plugged solid. After soaking it and everything else overnight, I ran compressed air through all the little passages that I could see. Put it all back togeather and it started second pull and runs great. You may have already done all this, since you replaced the needle, but thought I would at least add it.

I rebuilt the three carbs and fuel pumps on my Merc 1000 recently and the new needles that they gave me required alot of tweeking once I got them in so that they opened and closed the correct ammount according to the instructions. The needles were fine, but the two open and close levers that the float activates needed to be tuned up quite a bit so that they all worked properly. Apparently the needles that they gave with the rebuild kits were a bit longer than the origional ones. Just a thought if you hadnt done that yet!

 

[Willard]

Re: Old Merc won't work

Thanks to everybody for the good advice. Rebuilt the carb but still will only start with fuel in spark plug hole. Tried squeezing the bulb. Motor runs for 10 min. then revs up on its own and quits. Will rebuild or replace fuel pump asap as I'm sure by the paint that this is original. Will also recheck my float settings.
Willard

 

[nos1013]

Re: Old Merc won't work

Don't forget the fact that a quick disconnect allowing air into the fuel line can cause a lot of cold start problems. Mercs are cold blooded from the start, and air in the fuel line can make things worse! This is only one possible theory, btw.
B

 

[Willard]

Re: Old Merc won't work

Don't forget the fact that a quick disconnect allowing air into the fuel line can cause a lot of cold start problems. Mercs are cold blooded from the start, and air in the fuel line can make things worse! This is only one possible theory, btw.
B

 

[Willard]

Re: Old Merc won't work

Update-Finally got time to work on the motor and replaced diaphram in fuel pump. Now I have too much gas to motor!
I am not complaining. Will adjust float again and needle valve. Thanks again for help.
Willard