5.0 mercruiser stalls warm under load???

[Dukeab]

I have a 78 century with a 305 mercruiser. It runs like a top when it's cold. As soon as it's warmed up and I come to astop and try to go it chugs out and dies. It will idle all day just fine just under load when it's warm. New plugs and wires cap and rotor coil rebuilt carb new points and condenser. I have also replaced the log style manifolds. Any ideas are good.....

 

[Dukeab]

Re: 5.0 mercruiser stalls warm under load???

I can also rev it up in neutral when warm just not under load.

 

[Bondo]

Re: 5.0 mercruiser stalls warm under load???

Ayuh,... Welcome Aboard,.... I'd give it a complete Tune up, 'n if that don't fix it,... Rebuild the Carb...

 

[Dukeab]

Re: 5.0 mercruiser stalls warm under load???

I have done all that.Rebuilt carb professionally plugs wires cap rotor points dwell set. Intake leak? I can rev it up in neutral just fine all the time
though. Just not under load when it's warm?

 

[dubs283]

Re: 5.0 mercruiser stalls warm under load???

is the dwell and timing set properly??

have you ever had a severe overheat??

long shot, but...when was the last time you changed the shift cable??

 

[NHGuy]

Re: 5.0 mercruiser stalls warm under load???

Chrck fuel supply and pressure. Have you changed all fuel filters? Is the spark arrestor clean?

 

[dubs283]

Re: 5.0 mercruiser stalls warm under load???

+ 1 on the fuel filters - there are at least two, a water separator and a carb filter (rochester carb)

fuel filters are part of a FULL tune-up

 

[Augie56]

Re: 5.0 mercruiser stalls warm under load???

Choke sticking or closing/opening when you don't want it to? Mine was worn out, and I wanted to keep it simple so I replaced it with a full manual choke....cable with pull handle, hidden in the gunwale. Now I can choke when I want to, and keep it off at all times when I don't. Never will fail.

 

[Fishermark]

Re: 5.0 mercruiser stalls warm under load???

Yep - sounds like the choke isn't opening or not opening fully when warm.

 

[8756tf]

Re: 5.0 mercruiser stalls warm under load???

Had the exact same thing going on with my boat last season ! I also have a 1983 305 with a 2 jet Rodchester carb. Did every thing you have done to your boat, only to find out the problem was the actual fuel pickup line going into gas tank on floor was slightly clogged with crap. My boat had same symptoms you are having, check your FUEL SUPPLIES !

 

[Dukeab]

Re: 5.0 mercruiser stalls warm under load???

Thank you every one for all of your input. I'm going to do all of that! I like the manual choke idea a lot too! I'll make a post in about a month when I get all of it done

 

[Dukeab]

Re: 5.0 mercruiser stalls warm under load???

Well i have replaced all the fuel lines, pickup tube, check valve, both fuel filters. Still having the same problems. Finally last time i took it out we cruised around for a while stopped and i couldnt get it to move. It would run just fine until i put it into gear. We timed it while out on the lake but could only get it to run good around 12* bdc shold be around 8* bdc. checked the timing chain to see if it is stretched. 5*-6* of play in the timing chain. I read thats within tolerance. Right? The thing is i can turn the shaft of the distributorwith my fingers not much but a few degrees for sure. is that normal? Is that a mechanical advance that replaces a vaccum advance? Secondly if the mechanical fuel pump is bad will it always leak into that glass bowl?