Mercruiser catches on initial cranking then dies..

[Saltwaterstinger]

Hey guys,

Mercruiser 350 engine with carb rebuilt last season. engine roughly a 1997-2000 crate replacement with about 100 hours on it. was running fine all season and when i have been going to the slip the past few days i try to start and it will catch for a half second but die. so i pump throttle and it does the same thing 1 more time. then i have to wait 15-20 sec and keep throttle wide open and crank for 15 sec until it catches and stays started with a little squeeling from the new alt until i adjust the rpms to about 1000-1300 to run for a few min to let it warm up until i can let it idle around 650-750 rpm. This happens every time i leave it for a few days. if i shut it off and restart within 10 min to an hour it starts up with only a little hesitation and with throttle half open.

I checked anti siphon valve on top of tank for function by blowing in both sides and it operated properly. I checked the pick up tube and screen which was free and clear. checked fuel filter and emptied it which seemed clear. The boat runs fine once it idles and runs fine once i leave the dock. and im running WOT at about 3600-3700 rpm at about 35-36 mph. Its a 3400 lb Larson hampton cuddy cabin. Does this seem like too low of a rpm at WOT? could my carb be leaking or is my fuel pump ( i believe its mechanical) failing?

 

[bspeth]

Re: Mercruiser catches on initial cranking then dies..

The WOT for my boat is 4400-4800,but check your manual for that information.It is not getting flooded is it?

 

[alldodge]

Re: Mercruiser catches on initial cranking then dies..

Hey guys,

Mercruiser 350 engine with carb rebuilt last season. engine roughly a 1997-2000 crate replacement with about 100 hours on it. was running fine all season and when i have been going to the slip the past few days i try to start and it will catch for a half second but die. so i pump throttle and it does the same thing 1 more time. then i have to wait 15-20 sec and keep throttle wide open and crank for 15 sec until it catches and stays started with a little squeeling from the new alt until i adjust the rpms to about 1000-1300 to run for a few min to let it warm up until i can let it idle around 650-750 rpm. This happens every time i leave it for a few days. if i shut it off and restart within 10 min to an hour it starts up with only a little hesitation and with throttle half open.

I checked anti siphon valve on top of tank for function by blowing in both sides and it operated properly. I checked the pick up tube and screen which was free and clear. checked fuel filter and emptied it which seemed clear. The boat runs fine once it idles and runs fine once i leave the dock. and im running WOT at about 3600-3700 rpm at about 35-36 mph. Its a 3400 lb Larson hampton cuddy cabin. Does this seem like too low of a rpm at WOT? could my carb be leaking or is my fuel pump ( i believe its mechanical) failing?

Sounds like your engine is being flooded. After she is warmed up, shut it off, puull flame arrestor and you probably have fuel dripping down the throut of the carb. This is why you can restart quickly by opening up the throttle a bit. If the carb was wrking correctly you shouldn't need to touch the throttle after just shutting it off.

 

[Bondo]

Re: Mercruiser catches on initial cranking then dies..

Hey guys,

Mercruiser 350 engine with carb rebuilt last season. engine roughly a 1997-2000 crate replacement with about 100 hours on it. was running fine all season and when i have been going to the slip the past few days i try to start and it will catch for a half second but die. so i pump throttle and it does the same thing 1 more time. then i have to wait 15-20 sec and keep throttle wide open and crank for 15 sec until it catches and stays started with a little squeeling from the new alt until i adjust the rpms to about 1000-1300 to run for a few min to let it warm up until i can let it idle around 650-750 rpm. This happens every time i leave it for a few days. if i shut it off and restart within 10 min to an hour it starts up with only a little hesitation and with throttle half open.

I checked anti siphon valve on top of tank for function by blowing in both sides and it operated properly. I checked the pick up tube and screen which was free and clear. checked fuel filter and emptied it which seemed clear. The boat runs fine once it idles and runs fine once i leave the dock. and im running WOT at about 3600-3700 rpm at about 35-36 mph. Its a 3400 lb Larson hampton cuddy cabin. Does this seem like too low of a rpm at WOT? could my carb be leaking or is my fuel pump ( i believe its mechanical) failing?

Ayuh,.... Last season don't count when it comes to carb rebuilds,...

1 douse of water or crud, 'n it ain't a rebuilt carb anymore,...

Yer Wot rpms oughta be 4400/ 4800 rpms,...

It sounds like a Carb issue, 'n not fuel pump, but ya could test it anyways,...

What's the Contents of the fuel filter look like,..??

 

[Saltwaterstinger]

Re: Mercruiser catches on initial cranking then dies..

Ok I'll start with the carb this afternoon. The fuel filter looked clean and clear of any debris and water.