4.3 mercruiser stalls out after idling

[jetsetc5b]

1993 4.3 LX mercruiser alpha thunderbolt IV, 4-barrel (of146995) stalls out after idling when accelerating. Also, some times is hard to start. Changed carb, checked fuel lines, checked anti-syphon, bypassed oil press. sw., 12 volts to fuel pump, and choke is open. I must use carb cleaner sprayed in carb to restart then goose he accelerator several times and then fuel is observed entering the carb. throat. Then the boat will run all day as long as I dont idle for extended time and try to accelerate. My guess is that the fuel pump is sticking during low periods of flow because I have a volt meter installed and the volts are always 12.3 VDC. Im not sure but i think its time to change the pump. Any other ideas would be appreciated.

 

[Don S]

Re: 4.3 mercruiser stalls out after idling

My guess is that the fuel pump is sticking during low periods of flow because I have a volt meter installed and the volts are always 12.3 VDC. Im not sure but i think its time to change the pump.

I think you are about to spend a lot of money for a pump that won't help one little bit. This is a case of throw money at it, and it didn't help.
Probably about a 99.9% chance that a complete tuneup (done correctly) and the carb adjusted and working as it should will cure your problem.
Trust me, you DO NOT have a fuel pump problem.

 

[jetsetc5b]

Re: 4.3 mercruiser stalls out after idling

Ok I believe you and will not buy a fuel pump. 99.9% is pretty sure thing . Plugs, wires, rotor, dist. cap, timing and carb adjust. Anything else? I will post my results so others can benifit.

 

[JustJason]

Re: 4.3 mercruiser stalls out after idling

yeah.... change your fuel filters...

 

[jetsetc5b]

Re: 4.3 mercruiser stalls out after idling

I changeg the fuel/water separtator, checked the carb screen filter checked the filter screen at the pump inlet. The water/sep had alot of water and rust in it

 

[wca_tim]

Re: 4.3 mercruiser stalls out after idling

have you cleaned out the gas tank? or better yet tried running it out of a gas can?

Without being able to look / hear it run it sounds like the needles are leaking and loading it up with gas when your idling... at higher throttle you're burning the gas.

 

[jetsetc5b]

Re: 4.3 mercruiser stalls out after idling

I pulled the pickup with the anti syphon valve off the top of the tank and it all looked good. I blew thru the anti syphon and the ball bearingunseats and sounds like a duck call.

 

[SeaRay175XL]

Re: 4.3 mercruiser stalls out after idling

Last year I had that exact problem and it turned out that the fuel filter was the cause! It had rusted on the inside which of course allowed rust to enter the carb. I pulled and cleaned the carb twice before finding the rusted filter.

 

[jetsetc5b]

Re: 4.3 mercruiser stalls out after idling

When I changed the filter it too had rust and water. I was sure I had found the problem then changed the filter but it still did the same. I have sinse put a factory rebuit carb and still the same issues. Thanx for the post. Im going to do what Don suggested and do the tune up.