Mercruiser 5.7L Bravo 3 - Intermittent loss of power (no stall) rough running

rocklydockly

Seaman
Joined
Jun 18, 2005
Messages
51
Rinker 232 Capitva - open bow 1995

Hull Number RNK46677K495

ENGINE SER. # OF287508
TRANSOM SER. # OF513273
OUTDRIVE SER. # OF224039

BRAVO III RATIO 2.20

QUICKSILVER PROPS
48-823667 A6 26P
48-823668 A6 26P

Had the boat out yesterday. First time of the season. Hard to start, starts right up when I spray starter fluid down the throat of the 4 barrel carb. I left it running all day because of hard start. Gauges all read normal. Worked great 93% of the 3+ hour session. 3 times while I was pulling wakeboarders or tubers, it kind of lost power or stumbled. I would guess the hard starting might be a failed accelerator pump in my carb. I would like to know how to figure out if I have primarily a fuel delivery issue or an ignition issue. I realize I can just start replacing parts on either side and maybe take care of my problem. I would rather focus on the real issues first rather than throw money at all of it. (Hope I didn't leave out pertinent details.)
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Mercruiser 5.7L Bravo 3 - Intermittent loss of power (no stall) rough running

Howdy,

I would start by replacing the filter. (cut the old one open and see if there's anything inside besides clean fuel)

Check your automatic choke. It may be stuck open (or shut) and/or is not operating.

I wouldn't use starting fluid.

If you have not replaced the dist cap/rotor, plugs etc in a couple of years, I would do it but your problem sounds a lot like fuel delivery.
 

rocklydockly

Seaman
Joined
Jun 18, 2005
Messages
51
Re: Mercruiser 5.7L Bravo 3 - Intermittent loss of power (no stall) rough running

Should I be able to see the accelerator pump squirt fuel down the carb? When we have sprayed fluid, two of the barrels have been open. Auto choke not working? Will work on it tomorrow after work. Planning to start on the fuel side with, filter/seperator, choke, accelerator pump. Test it. Move to cap, points, plugs, condenser thereafter.
 

rocklydockly

Seaman
Joined
Jun 18, 2005
Messages
51
Re: Mercruiser 5.7L Bravo 3 - Intermittent loss of power (no stall) rough running

Replaced Fuel Filter/Seperator and readjusted carb jets. Starts great, runs good. Accelerator pump is fine. Could probably use some fine tuning of the carb. Will learn more about this.
 
Top