Can low compression cause flooding?

[fsutim]

1978 70HP Johnson, I haven't checked compression and am curious if low compression in a cylinder can cause flooding. I have completely rebuilt the carbs and I'm still having the same problem. The engine starts up great on land but after trailering it and putting it in the water it wont start. Today when I launched it in the water I tried to start it and It wouldnt, so I took out all the spark plugs and cleaned the oil off them and it fired right up. I let it run for a couple minutes to warm it up and then I shut it off. After It sat off for about 5 minutes I tried to restart it and It wouldnt start again. I noticed some fuel pouring out of the center carb.<br />I'm sure I set the floats correctly and the needle valves are brand new. The spark plugs are also getting a good spark. Does anyone have any ideas about what I should try next, and Also if compression may play a part in this?

 

[Solittle]

Re: Can low compression cause flooding?

Tim - Your description still fits the "got crud in the carbs" diagnosis. Did you remove the jets? Did you soak everything overnight? Did you use high compressed air to blow out all the little passages that you cannot see? For further info check here:<br /><br /> http://www.outboardrepairs.com/carburetors/

 

[OBJ]

Re: Can low compression cause flooding?

Hi Tim....<br /><br />When you set the float, did you set it with the carb body upside down and set the float level with the float bowl gasket surface? And are you sure you replaced the nozzel gasket?<br /><br />Just another question or two....when the gas was "pouring' out, does that mean like a steady stream? Does it do it when you pump up the primer bulb?<br /><br />Sorry for all the questions...just trying to get a feel for the problem.

 

[fsutim]

Re: Can low compression cause flooding?

Thanks for the replys,<br />I did soak most parts over night, and did use compressed air to blow through all passages. I put the float bowl upside down and set it about 1/8 of an inch above the gasket. I used all gaskets that came with the rebuild kit. I'm not sure what the nozzel gasket is?<br />When I pump up the primer bulb gas doesn't start to pour out, I stop pumping when the bulb is firm and at this time no gas is pouring out of the carb. The other day the carb that I noticed was leaking fuel was the middle carb. This happend after I started to try and crank it a few times, gas then oozed out, it didnt seem like it was a steady stream it just was enough to overflow out of the carb and pour down the front. I then stoped trying to start it.<br />Could a damaged fixed high speed jet orfice cause this problem. I know my carb has a fixed high and low jet and I haven't been able to get out the high speed jet becuase it requires a special screwdriver. I did blow compressed air through the passage but I'm not sure if this could possibly be damaged by me trying to remove it with the wrong tool. If it was damaged could this cause possible starting problems? Thanks for the help, Tim.

 

[james roach]

Re: Can low compression cause flooding?

Sounds like the needle in that carb is sticking. That is usually why gas pours out the front. Sounds like a piece of trash is stuck in between the needle and seat. My motor did this once and when I pulled the carb, I found some welding solder from the tank in there. A 5$ in-line filter took care of this. Good luck

 

[fsutim]

Re: Can low compression cause flooding?

Before I took the boat out last time I took the carbs apart and cleaned them, From what I noticed the needles were not sticking or there wasn't anything blocking them.

 

[james roach]

Re: Can low compression cause flooding?

If there is trash in your tank and line, in the time it takes you to pump the carbs full with the bulb is enough time to make the needle stick open. This would require no more than taking off the one carb. It wont cost anything. When mine did this, you could see the gas running out of the top of the carb. I took it off while on the water and found the solder in the needle and seat. I took it out and put the carb back on. It ran fine for about a mile until the next piece of solder got in there. I got the boat back on the trailer and cleaned the carb out again. This time I put the in-line filter on the gas line and that was 2 years ago with no carb problems since. This may not be your problem but then again it's possible.

 

[R.Johnson]

Re: Can low compression cause flooding?

Cranking that engine any lenght of time with the choke closed is drawing raw fuel into the carb barrel, and it will dribble out the front. You said you could not remove the high speed jet, and may have damaged it. To make that "special tool" buy a philips screw driver with a 3/16 shank. Saw the shank off about three inchs ahead of the handle. With a file, file a flat blade that will just fit the slot in the jet. You now have an OMC " special tool" I have seen jets clogged so tightly with varnish that they were a bear to remove with any tool. Take the carbs apart and soak them overnight. Then take a propane torch, and carefully heat the float bowl where the jet is seated. If the jet is damaged, replace it. The nozzle gasket is the gasket around the brass tube in center of carb body. I think you still have some varnished passages, not a needle and seat problem. I did a carb this fall where the man told me he just cleaned and installed a new kit. I danced with it a couple of hours, took it apart, and put the float in upside right.

 

[Hooty]

Re: Can low compression cause flooding?

No. Low compression will not cause flooding.<br /><br />c/6<br />Hooty