1978 Evinrude fuel to air ratio?

[alumboater]

I have a 1978 70 HP Evinrude. When I start the engine it seems to flood really easy. I can try to start it, but I alwys have to take the air silencer off and let the carbs get more air. I will crank the motor over several times and then it will start coughing. I crank it a few more times and then it fires up. My question is Is there an adjustment that can be made that will relieve the flooding problem. I am assusming it is flooding due to the amount of fuel that is in the bottom of the air silencer when I remove it. Anyone have any direction?

To start the boat I hook up fuel line, pump bulb, turn and press key in to choke it. I also pull the warm up lever on the side of the control up. If the boat starts and then dies thats when the problem begins. Once the motor is good and warm I don't have any problems at all, it will start up first crank no problem. What do y'all think.

 

[boobie]

Re: 1978 Evinrude fuel to air ratio?

I think you should do the basics. Check your compression, then your spark. Spark should jump a 7/16 " open air gap on a tester. If they both pass then look into the carbs.

 

[alumboater]

Re: 1978 Evinrude fuel to air ratio?

When cold the motor has 115 on all cyl. I checked spark and all fire fine. The motro runs fine once it warms up for a while. It is just the starting it cold that creates a flooding like problem.

 

[boobie]

Re: 1978 Evinrude fuel to air ratio?

How did you check your spark ??

 

[F_R]

Re: 1978 Evinrude fuel to air ratio?

So....you are doing everything correctly, at least up to the time it starts and dies. THEN what do you do?? Do you continue to choke it? Maybe that's your flooding problem. Are you NOT choking it any more? Maybe that is your problem. (It may not be flooding after all). I don't think you have an engine problem, I think you have a technique problem. Some motors are unique one way, some another.

EDIT: You said you turn and push the key to choke it----are you HOLDING the key pushed in while running the starter? You should. Actually it is pretty hard to flood a cold motor, and even if you do it should clear out and start by not choking it any more.

Yeah, yeah, I know, it isn't a "choke" it's a "primer". Result is the same.

 

[alumboater]

Re: 1978 Evinrude fuel to air ratio?

Boobie
Checked the spark with (forgive me for not knowing the exact name) a spark tester. I have a buddy that has a piece of equipment that you unscrew the plugs and screw these in and crank the motor. All sparked just fine. Sorry for not knowing mor about the piece of equipment that I was useing.

J_R
I only hope it is opperator error!!! I do hold the key in as I crank the motor. Once it dies I then push the key and hold it in and attempt to start it again. If it does not start then I try to crank withour pressing the key in. Nothing. I can tell when it is about to start it will make a coughing noise. Once it makes that coughing noise I know in about 3 more attempts it will start. The last time this happened I had the motor trimmed up a little and there was a puddle of fuel in the front of the air silencer. When I pulled the air silencer I could see there was fuel coming from the carbs. There was not fuel coming from them while I was just sitting there, but when I attempted to start it there was fuel coming out. This is what led me to believe I was flooding the motor. If I just pull the air silencer off and crank it a few times it will start. This leads me to believe that there is to much fuel and not enough air (but I am NO expert by any means)

Thank you guys for your time

 

[emdsapmgr]

Re: 1978 Evinrude fuel to air ratio?

Youv'e mentioned repeatedly fuel in the bottom of the airbox. Many of these older carbs do tend to leak small amounts of fuel out of the carb throats when the engine is tilted. Probably a fine line between a little fuel leak and an excessive leak. That excess fuel accumulates in the bottom of the airbox and is then recirculated into the bottom cyl for combustion-via the airbox drain hose. When the engine starts up, that bottom cyl frequently is overfueled and makes it hard to start. Further, upon initial start, the engine will smoke a lot for the first minute or so-till the excess fuel is burned off in the bottom cyl. You may need to overhaul the carbs, paying attention to the condition/adjustment of the floats.

 

[alumboater]

Re: 1978 Evinrude fuel to air ratio?

Yeah there, at times is an excess amount of fuel> the fuel leaks out of the bottoem of the air silencer and into the motor case and puddles up there when tilted. I believe I will wheck the carbs. Is there an adjustment with the amount of fuel that the carb alows through or is that regulated by the float inside the carb?

 

[Silvertip]

Re: 1978 Evinrude fuel to air ratio?

There are several things that can be out of whack on a carb but your issue may be floats that are not properly adjusted. If the float is set too high the level of the fuel inside the float bowl is too high and it can flow out of the carb and easily flood the engine, especially when tilted even a little bit. Inlet needs (operated by the floats) that are sticking open or otherwise not sealing when the float raises can also cause high fuel levels. That and starting procedure are the normal suspects. Have the engine full down when starting.

 

[F_R]

Re: 1978 Evinrude fuel to air ratio?

Aha!! When trying to start a tilted motor, there is not enough airflow through the carburetors to carry the fuel into the intake manifold. So, where does it go? It runs downhill, out into the silencer. Gravity, y'know.