3.0 wont start after it warms up

[scottn83]

I have a 3.0 Mercruiser it will start first time fine but after warming up and then sitting 1/2 hour just refuses to fire off. It will start if you shut it down and then start it right back up. Can anyone point me at some things to check that could be causing this

 

[alldodge]

I have a 3.0 Mercruiser it will start first time fine but after warming up and then sitting 1/2 hour just refuses to fire off. It will start if you shut it down and then start it right back up. Can anyone point me at some things to check that could be causing this

So many of us forget the basics when asking a question. We could look back at your post and find out what you have but it sure is easier if you tell us the serial number or year. Maybe put it in your signature

I'm guessing you have a carb and electronic ignition. Do you know if your getting spark? What kind of ignition system do you have? My first thought is your coil is getting hot and after it does some heat soaking it stops working until it cools. Then again this could also happen with the ignition module

 

[boozer1966]

I have a MCM 140 that had a similar problem that I resolved by replacing the impeller and thermostat. Engine was running a little hot which was causing gas in the hard line running from fuel pump to carb to vaporize if sitting for very long. Check engine temp.

 

[Fastatv]

I have a 3.0 Mercruiser it will start first time fine but after warming up and then sitting 1/2 hour just refuses to fire off. It will start if you shut it down and then start it right back up. Can anyone point me at some things to check that could be causing this

My best guess is that during the half hour or so after shutting off, the heat in the engine compartment may be causing fuel to percolate a bit. Next time it happens, place the hand control in throttle only position, slowly move throttle about 1/4 travel forward....then try to start. Be ready to quickly pull the throttle back to idle position.

 

[scottn83]

First of all I have am not sure of the serial number but I have a points type distributor. I have made some progress. I didn't note before that it is even hard to start at the git go. The problem was worst after sitting all winter. I cleaned the points and adj them they were way out of adj didn't seem to even open with the engine was turned by hand. It is still a bit hard to start takes quit a bit of cranking but it will start. I am at this moment giving it a time to sit and going to go back up soon and try to start it again. I am considering going to electronic ignition.

 

[bspeth]

Anybody think the fuel bowl is leaking?

 

[scottn83]

ok i think the starting issue was the points after adjusting them it seems to be behaving started it multi times with about 30 min between starts like it may be if i was sitting on the lake. Thanks for everyone's input

 

[Fastatv]

ok i think the starting issue was the points after adjusting them it seems to be behaving started it multi times with about 30 min between starts like it may be if i was sitting on the lake. Thanks for everyone's input

Hopefully you have it...have fun with your boat!