40 merc hard to start hot

[hydrostream1]

I`ve got a 40 merc that after you run it for a while in the water,let it set for a few minutes then is hard to start.Will hit a few times,once it starts rev it in neutral a few times it will idle then dies when you give it throttle in gear.Carbs have been cleaned ,gas is pure ,no water in it.new fuel pump and has an additional electric pump.Starts right up cold,runs out to 5,500.Idles good cold. I also checked the idle mixture screws to the manual specs and played with them quite a bit,It didn`t help it any hot starting.Iam getting ready to check the stator ohm values with it hot.Do you guys have any suggestions.Thanks

[Winger Ed.]

Just a wild guess, but it sounds like it may not be getting fuel, or its trying to flood.


I had a outboard once that did that on one tank. Different times with another, it didn't.

I thought I was going crazy... how did it know which tank I was using?

I found out that the strainer inside the one tank had some goo on it, restricting flow.



Another thing to look for is if its percolating the fuel out of the float bowl.

Some of it will vent or go over into the crankcase. Then when you start it, it will be running rich for a bit until it clears itself.

Next time out, you might try pumping the primer bulb to see if fuel fills the bowl after its been shut off a few minutes or so. That will tell ya the fuel in there went somewhere too soon to evaporate.

If that's the case, you might also have a overheating problem.



What I did with another - a Chry. 50- that was a dog to start when it was hot was to unplug the fuel and let it run itself out, if I was just going to beach it a while or stop to fish.

Then, plugging in the fuel line, and pumping the float bowls back up worked OK until I actually found and fixed the flooding condition on one carb.




Oh, something else that'll just make ya crazy is that it won't ever act up at home running on the hose. But as soon as you get to the lake, it shows its rear to all.

A old guru told me it was due to the extra back pressure of water filling up the middle unit when in the lake. The engine has to do a little extra work to push the water out of its 'exhaust pipe'. On start up, its going its slowest and at its weakest, so that sort of adds to any starting problems you already have.



Good Luck.
on start up.

[hydrostream1]

I actually had to use the primer on th key switch to help it start.Which tells me its lean.The primer bulb is full,I checked it before i started it hot.I was reading in the manual some igntion diagnostic troubles.One of the problems in the manual said the timing protection module could cause a hard hot start.By the way this was a factory manual.