Gas coming out carb

[Siv]

I have a 1981 Johnson 70hp. Last year I had a problem where it idled fine but when I went to put it into gear it I would have to slowly throttle up (over a matter of minutes not seconds) until finally the motor seemed to start picking up and then I could give it full throttle otherwise it would just die. I had cleaned the carbs at the start of the season but I may have done something wrong.

This year when I put it in gear it will go forward but only at very slow speeds, any extra throttle and it dies I can't nurse it up to speed like last year.

I was working on the motor today doing a bunch of stuff that I probably should have done before being an old motor such as rebuild fuel pump etc. I had the air silencer off and pumped the primer and after a few pumps gas was coming out of the air intake on the bottom carburetor. Is this normal or is something wrong inside this carb? I don't want to take them all apart and spend another $90 on 3 carb kits if this isn't my problem.

FYI:
Engine compression from top to bottom is 110,108,106
Carbs rebuilt last year but by me not professionally, I may have done something wrong. I took them all apart and soaked them overnight in "heavy duty parts cleaner" that says its for engine parts, carburetors, etc. then blew compressed air through all the passageways.

Thanks for reading

 

[Dabbler_E]

Re: Gas coming out carb

Idles fine, won't power up worth a darn, fuel coming out the carbs: sounds very much like what happened to me last year, which was one flooded cylinder. Lots of false starts before coming back to the carbs -- a valve needle had a bit of gunk on it so fuel flow wasn't being shut off by the float valve, flooding the cylinder. Check your plugs: one is likely very wet. Then run the engine and pop the wire off that plug and see if it changes how the engine runs -- if not, that cylinder isn't firing. Check to make sure that the plug is actually giving spark. Assuming it is, your next step is to very meticulously clean & rebuild the carb for that cylinder.

In my case, the ultimate cause was that I changed fuel lines and didn't flush them out, so some itty bitty bit of sloodge worked its way into the float valve and ruined my day (actually, it was a couple weeks before it was solved).

Hope this helps!

 

[Dabbler_E]

Re: Gas coming out carb

Here's the link to the thread on my prior problem.

 

[greenwell001]

Re: Gas coming out carb

i had a similar problem with my two barrel mercarb on my 5.7....sta-bil which i will never use again had my carb so clogged up that my jets werent spraying they were dribbling drops of gas and causing it to run very rich.....which causes it to be very cold natured and takes a little more time to get to operating temp, not to mention all the black smoke coming out of the exhaust and horrible gas mileage.....try an entire rebluild on the carb and you dont have to soak it just get some carb cleaner from a parts sore and make sure you spray it through the jets and all of the needle valves...in other words spray through every tunnel and the pressure from the spray will push any gunk out no problem....get the specified rebuild kit wih all the gaskets and need valves and you should not have any problem and dont forget to set your elctronic choke if you have one....i have see a few get stuck....i got my complete rebuild kit for about 39 dollars locally....this is a long shot but you may need to check fuel pressre as you pump may be going out....but this i what fixed my problem and its just and opinion so take it with a grain of salt because i had proffesionall help from my unlcle who builds 20000 dollar sprin car engines

 

[jtexas]

Re: Gas coming out carb

gas coming out the carb throat means the float valve is not seating correctly.

could be misadjusted float height, or could be worn valve or valve seat.

did you replace the valves *and* seats with the new ones from the kit? And the o-ring under the valve seat -- any chance you might have forgotten it?

you can check float valve operation by blowing into the fuel inlet. Carb held upside down, no air should pass; right side up, should be very little resistance. I recommend draining the carb bowl first; premix is an acquired taste.

BTW I don't know where you've been buying $30 carb kits, but iboats has 'em for about $12 apiece.

 

[71Windsor]

Re: Gas coming out carb

Thats where I would go back to. Even after taking the carbs off and cleaning them if you have anything in your tank or lines it will just go right back to the float and flood your engine. Have you changed your fuel lines to new approved lines for ethanol? (Alcohol resistant fuel lines). You could clean your carbs a hundred times the new fuel will keep junking them up with the wrong fuel line in use.

Id change / clean filters, check fuel line, re clean carbs making sure the float and passage are clear and clean. The float should look PERFECT no nick's scratches or dings.


Cheers
Frank
Pennsville NJ

 

[kenmyfam]

Re: Gas coming out carb

Float valve.

 

[Siv]

Re: Gas coming out carb

Thanks for the help guys. I took the carbs apart and couldn't see any blockages anywhere but sprayed some carb cleaner in all the holes. Put everything back together and threw them on the boat. Tried pumping the squeeze bulb and it got firm with no gas coming out the bottom carb anymore. Started it up and let it run for a bit then turned it off and the squeeze bulb was still hard where as it would have been flat before. Going to try to get it on the water tomorrow and try throwing it into gear hopefully it's fixed.

As for the comment about the price of carb kits
Local store= $32*3=$96
IBoats= $15*3=45+30 to ship to Canada=$75 +duties
the extra $20 it would cost at the local shop is worth it to me because I can have the carbs rebuilt in a day rathter than waiting 1-2 weeks for the parts to come in. If I lived in the states I would probably buy them online.

 

[Larry Hartzell]

I have a 1992 5.8 with a new carb old carb did the same thing. when cranking it will not fire, the gas mist back up out of the carb with the filter off. Filter on it all stays in the intake. If i put gas in a cylinder it will fire on that cylinder but will not run.

 

[GA_Boater]

I have a 1992 5.8 with a new carb old carb did the same thing. when cranking it will not fire, the gas mist back up out of the carb with the filter off. Filter on it all stays in the intake. If i put gas in a cylinder it will fire on that cylinder but will not run.

Start a thread of your own. This one is over 10 ten years old and is for a 70 HP motor, so you are off by 64.2 HP!

Closed.