Johnson 140 4-stroke losing power

I’m in a bit of a quandry–
My “new to me” pseudo-rebuilt 2004 Johnson/suzuki 140 has a habit of losing power at cruise from time to time. The problem seems to be related to fuel delivery. It’ll be running along just fine at speed (3500-4500 rpm) and it bogs down to idle, and sometimes it will die completely. If I pump the primer bulb when it happens it always regains it’s vigor right away. It does not happen on a perfectly regular basis, but usually acts up at least once or twice when I am out on the water. I figured I was “sucking air” somewhere. So far to attempt to fix the problem I’ve found and fixed small leaks at by fuel/water seperator, new seperator element, replaced my primer bulb with a OEM BRP bulb, replaced my low-pressure fuel pump, replace the under-cowl fuel filter, replace my anti-siphon valve at the tank and re-teflon-taped all the fittings. The main fuel line is 3/8" and is only a few years old; it’s heavy-duty marine fuel hose.

The motor has a OMC fuel connector on the front (not hard-lined in). I’m going to replace the fuel lines under the cowl, but I’m just about at a loss… any suggestions? Sound familiar? Thanks in advance.

Bueller? Anybody?

Would it cause problems if I knocked the guts out of my anti-siphon valve thus converting it into a plain barbed fitting?

Baker
Old, beat up 17’ McKee

Not sure about the 140’s but does it also have a high pressure fuel filter?? my 175’S do and have cause a problem in the past

26’ Twinvee Cat
Twin Suzuki 175’s
www.creeksidemetalworks.com

When it stars doing it again check your fuel gauge cause mine will do this if I have less then 1/2.
I have done everything you said and should have started with the most simple 1st

2008
Ranger Banshee Extreme
Yamaha 60

My buddy has the same exact motor, although newer, and went through the same exact symptoms last year. It was ethanol related. ChrisV @ ChasMarine had to replace everything rubber in his fuel system and it works great now. He only uses ethanol free gas now and will go out of his way to find it (paying for premium too).

Not sure it’s the same exact issue, but it sure sounds like it.

KeyWest 1720cc 90 Ymha

you need a vacuum gauge and a piece of clear tubing
check vacuum and look for air leaks

www.teamcharlestonmarine.com
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