Mercury 150 Hard Start when Hot

Author Message   GatorMan New member Username: gatorman Post Number: 1 Registered: 06-2009 Posted on Sunday, June 28, 2009 - 06:40 pm:    Hey guys, This is my first post, but hopefully not my last. I tried searching the site, but haven't come across my issue, so I hope I'm not naive in my expectation. I've always had inboards and this is my first outboard, which seems to be much harder to diagnose. I've got an issue that has popped up right at the height of my boating season and I'm hoping someone can narrow down my starting point, before I have to kill alot of time walking through trial and error testing. Engine: 2001 Mercury 150 Saltwater Problem: Cold engine starts fine, runs fine. When I turn off the engine, I can't get it to restart for 35-50 revolutions (i'm estimating). I generally pump my fuel bulb to get it hard (I don't know if it should stay hard all the time-please let me know), depress the neutral release and crank the engine at full throttle. It trys to die, but as long as I keep working the throttle until I can get it in gear, then everything is OK. As long as I don't turn the engine off it will run until I run out of gas. I looked up on SELOC (which I am beginning to dislike due to their ambiguity on many topics) to try and figure this one out and this is what they printed: "When the engine is hot, the fuel system can cause starting problems. After a hot engine is shut down, the temperature inside the fuel bowl may rise to 200 degrees F (94 degrees C) and cause the fuel to actually boil. All carburetors are vented to allow this pressure to escape to the atmosphere. However, some of the fuel may percolate over the high-speed nozzle. If the choke should stick in the open position, the engine will be hard to start. If the choke should stick in the closed position, the engine will flood, making it very difficult to start. In order for this raw fuel to vaporize enough to burn, considerable air must be added to lean out the mixture. Therefore, the best remedy for a flooded motor is to remove the spark plugs, ground the leads, crank the powerhead through about ten revolutions, clean the plugs, reinstall the plugs, and start the engine. Another common solution to a flooded motor is to open the throttle all the way while cranking (using the additional air to help clear/burn the excess fuel in the combustion chambers), but the problem with marine engines is that might put the gearcase in FORWARD (unless there is a neutral lockout on the shifter) which will prevent the starter from working on most models. " So I don't know about you guys, but this doesn't appear to be a very good solution. Since this sounds to be more common problem, I'm hoping someone has a more common solution. I just want to turn the key and make it go. I know it seems to much to ask, but I'd rather not sit there trying to crank it over and over and over and over, until it ROARS to life at full throttle. One day someone will build a motor that actually starts on the first try. BTW, I put new plugs. Made a big difference on cold starting, but not on hot starting. Any help is appreciated. GatorMan   ian summerfield Member Username: budgie14 Post Number: 30 Registered: 06-2009 Posted on Sunday, June 28, 2009 - 08:01 pm:    Hi,do u always pump the primer bulb,even after the initial start?once the motor goes and u stop it,try just restarting without touching the primer bulb or using full throttle.[most modern outboards wont allow full throttle,unless in forward gear]try that.or was that your original way of starting?   GatorMan New member Username: gatorman Post Number: 2 Registered: 06-2009 Posted on Tuesday, June 30, 2009 - 08:01 pm:    Ian, Thanks for the reply. That was the original way I started, but I can't seem to get that result anymore. The whole pumping the primer bulb is a recent activity to determine if I'm having to compensate for fuel pressure leak in my mind. Question: Should the primer bulb stay hard all the time? The Seloc manuals mention Fuel Pressure leaks, but my tank is built into the boat and I can't find a fuel pressure valve.   ian summerfield Member Username: budgie14 Post Number: 40 Registered: 06-2009 Posted on Tuesday, June 30, 2009 - 08:42 pm:    Hi,when a motor has been going,the primer bulb will generally allow a small squeeze,but shouldnt need actual pumping.the fuel pump is "sucking"[awful word] fuel thru the primer bulb,and the oneway valves stop the fuel draining back into the tank[plus the vacuum created].Needle valves in the carbis could also be leaking,allowing flooding when stopped   GatorMan Member Username: gatorman Post Number: 4 Registered: 06-2009 Posted on Tuesday, June 30, 2009 - 08:53 pm:    That's what I thought, but this is my first outboard in 20 years of boating. The primer bulb need about 20 solid squeezes to get hard again. How do you test a needle valve leak?   ian summerfield Member Username: budgie14 Post Number: 41 Registered: 06-2009 Posted on Tuesday, June 30, 2009 - 11:04 pm:    You shouldnt need to pump 20 times.Id buy a new primer bulb,they dont last long.about 3 or 4 good sqeezes should be ample,and if u can c into the carbies,there shouldnt be any excess fuel dripping out[indicating needle valves dirty or worn]Might need a marine shop to check it out,unless Graham has some suggestions.carb rebuilds?   GatorMan Member Username: gatorman Post Number: 5 Registered: 06-2009 Posted on Sunday, August 02, 2009 - 08:26 pm:    Well, here's one that has driven me to question. I spent weeks trying to diagnose this issue. Couldn't figure it out, so took it in to the shop. The culprit...a bad CDI module. Now I've spent weeks trying to determine how I could have identified this. SELOC has been no help. Gatorman   'Bandit Advanced Member Username: timebandit Post Number: 788 Registered: 09-2007 Posted on Monday, August 03, 2009 - 08:35 am:    SELOC is no help. The factory manual is the thing to have.

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