25hp Evinrude sucking air!

[pushdeck]

I have a 80's Evinrude 25hp outboard tiller and was out running it on and off for about 2 hours when I went to move spots and it wouldn't rev up, it will idle and just over but any higher it cuts for a sec then tries to rev then cuts then tries to rev.

Tried:
Checked fuel filter
New Plugs
New fuel lines on engine
Re-did primer and tank line (with stainless clamps)
Re-did tank line fitting on tank
Cleaned Carb (spotless when taken apart, blew out to make sure)

However the same problem re occurs. I put clear/blue fuel lines from choke pull, bottom block, and off the T to the carb. Seems to be no fuel coming in from the bottom of block line, and lots of air going through from the T fitting to the carb. This can't be right.

Any suggestions as to why this could be happening?

Thanks for the help in advance!

 

[Barnacle_Bill]

Re: 25hp Evinrude sucking air!

Did you check the fuel pump?

 

[1946Zephyr]

Re: 25hp Evinrude sucking air!

Sucking air is a result of a bad fuel line (cracked) or o-ring at the fuel line connector.

 

[pushdeck]

Re: 25hp Evinrude sucking air!

I checked the fuel pump, clean as can be. I tightened it up a little and no change. I however forgot to put the spring back on the plastic push piece that pushed back on the diaphragm but it was running without, of course I put it back once I realized. No change. The lines are all new and been spraying wd 40 on connection spots and no change. Lines are new, no cracks and all connections seem to be fine. The part that is weird was that I was out all day, stopped, started it up and then it had the problem. Tank fitting is tight.

 

[pushdeck]

Re: 25hp Evinrude sucking air!

If it was an o-ring on fuel line you would think that priming the bulb would compensate, but it doesn't. The connections (lever, evinrude/ johnson) are relatively new, garage kept, year old, used 10 times maybe. Is there a different o-ring that you are talking about?

 

[pushdeck]

Re: 25hp Evinrude sucking air!

used some needle nose to clamp the line coming from the choke pull to the T that goes to the carb and bottom of block, revs up and runs better. Weather getting to bad to take out in the lake 2 miles from house. Thinking about removing that line and the line that goes to the bottom of the carb and try a load test. Is the line that goes to the bottom of the carb (larger ~3/8) the choke pull what feeds the carb? so if i plug both ill be dead in water?

 

[pushdeck]

Re: 25hp Evinrude sucking air!

So I figured out (I think anyway) that its leaking air from the choke/primer pull, took it apart and put some AC O-Rings that I had laying around in and seemed to be fine. Took it out and ran fine, then when putting on the trailer and pushing boat up it started the same problem again. Think maybe air is still getting by there just need to get the right set of O-Rings, there is a flat sided one as well, but used a round, hopefully that will work.

Will pull it out tomorrow to work on it some more and see, will reply with the aftermath then.

Thanks for the input.