Engine won't start

planesailing

So I went to the boat today with the intention of changing the oil. I started the engine to warm the oil up and it fired straight up as it always does with 1 turn of the key. I left it running for 10 mins to get it up to temp and it run without issue and got up to temp with no problem. I shut the engine down and went to get the oil from my car. When I got back I tried to restart the engine just to make sure it was fully warmed up before changing the oil. It fired up straight away but after about 5 seconds it started sputtering almost as if there was a lack of fuel and then died. I tried to restart and exactly the same thing happened, it fired up then splutters and the engine tried to rev up but it then dies. It did this several times but now it just turns over but won't fire up. The tank is about 50% full with fresh fuel (filled up last month). Engine is a mercruiser 5.7 efi. Plugs and leads were changed last season and cap and Rota the end of the season before. Any ideas?!?

Handymans342

Do you have that cool fuel thing with the screen filter?

planesailing

I don't believe it has the cool fuel module. It's a 2000 model fitted to a 242 fiesta vee 

randy56

Sounds like no fuel, if that is the carburetor model, there is a screen where the fuel line goes into carb, could be clogged. if you remove fuel line hit the key a short burst and see if any fuel come out.

howardrams

How about if it's the type with the spin-on fuel filter/water separator.  I've had older models with carburetor collect a lot of water in the float bowl if the water separator isn't changed especially after all the condensation in the fuel tank over the winter.

planesailing

So I just got back from the boat. Went with the intention of checking fuel filters but when I got there I thought I'd try and start it and the engine started straight up. Any ideas what it could be?

212rowboat

heat... vapor lock.... next time, put it in neutral and open the throttle 3/4 to full... hit key with hand on throttle, back it down as soon as it fires.  it get's warm sitting at idle with small volume of water flowing, and when you kill it that water does nothing but get hotter, which cooks the fluids off making it get even hotter.... also- how long since you swapped impellers on your raw water pump? ....... another way to 'fix' this is to pull the negative terminal on your battery-to-engine... let it sit for about ten seconds and re-affix it... the computer is pulling fuel and adding spark because the temperature sensor is telling it to do so- clear its STFT and try again.      

planesailing

@212rowboat I did suspect it may be vapour lock. Would this happen after just 15 mins at idle and then being switched off for 10 mins? Impeller was changed the season before last so could probably do with being changed. Any other preventative measures to take yo prevent vapour locking? 

Liberty44140

Do you turn the key to the on position for 5-10 sec before starting? I always do. The guy in the dock behind me had starting issues with is merc 6.2 and our tech came down and fired it right up. He turned the key to the on position first and said you should always do that to start the fuel pump, then start the boat.