I have posted about this issue before and never figured out what is causing it. Here it is again this year with a new twist and maybe someone has solved the same issue in the interim.
Mt 2003 225 OX66 Vmax (VX225TLRB) generally runs like a top. I have one issue and that is when you have a cold day to start off and then it warms up later in the day (generally in the spring months). Under these conditions I sometimes have a hard time getting the motor to start. It is like it is starving for fuel. I can tilt the motor up a ways and then it has always started. Here in the last couple of months a new twist has happened as the motor has run out of fuel on me when I go to take off. This has happened twice both times on warm afternoons after a cold morning and then fishing in one location for a while. After the motor shuts down I can go back and pump the bulb up hard and then it runs fine again. It is like the fuel has siphoned back into the tank despite the one way valve in the engine fuel line (have replaced this also) after the motor fuel filter. These symptoms only happen when it is cold and then gets warm/hot later in the day. If it is hot/warm to start off or stays cold all day never have an issue.
I have two 32 gallon fuel tanks, then a fuel selector switch, then a water separating filter, then bulb, and then on to the engine. I replaced the primer bulb last fall and the needle valve in the VST several years ago and it still does this. I have also replaced the fuel line from the water filter/separator to the engine. I have cut the tank lines at the tank barbs and reattached them to make sure I was getting a good seal. I removed a anti siphon barb at one of the fuel tanks and replaced with a regular barb. The other tank just had a regular barb. The bulb pumps up like it is supposed to and is next to new. I think I must be sucking air somewhere in the fuel line, yet not leaking fuel. I have a manual fuel selector switch that allows you to switch between port and starboard tanks. I cannot say if this only happens on one tank versus the other. The switch is original to my 1999 Ranger 492VS but seems to function like it is supposed to. I am going to replace that next thinking it is sucking air there. What confuses me is that tilting the motor allows it to start, which to me says maybe the needle valve in the VST is the culprit. Upon dissasembly and inspection the float in the VST has looked fine. To me the needle valve also looked good. Though maybe I was getting vapor lock in the tanks but open the fuel caps and do not get any rush of air into the tanks. The recent shut downs may be a completely different issue, but it happens under the exact same circumstances as the non-start, which makes me think they are related.
Anyone experienced this issue or have any better ideas on how I might diagnose? Anything else I might take a look at? Thought about using some clear line to look for bubbles in the fuel to isolate the issue. I have a mighty-vac and thought I could vaccum/pressure check each section of line. I am going to be pulling the bench seat anyway to replace the fuel selector switch so have access to all the fuel lines.