No power under load

[anubix00]

i have a 2000 125HP mercury outboard on my 19' pro line sport. i am having a loss of power issue, and am not quite sure where to turn. ill try and keep this as short as possible

- launch boat, warm engine, and proceed to get one plane
- engine runs up to about 3200rpm and stops there. boat wont get on top
- shift back to neutral, warm up some more, i am able to exceed the 3200rpm when revving in neutral (i only do it for a second as a test)
- put boat back in gear and same result.

it seems like the engine randomly does this throughout the day. after that instance, i anchored off to swim and kill some time. when we decided to leave, the boat reached WOT and hopped right up on plane.

ive changed the plugs and wires, water/fuel filter, inline filter to carbs, carbs recently cleaned and inspected. i have new gas with stabilizer added. squeezing the fuel primer bulb didnt seem to have any effect on the engine during the loss of power.

 

[CharlieB]

Re: No power under load

Intermittant problems can be the toughest to sort out. When it occurs you still need to determine if it is a fuel or ignition related problem.

When the RPM hangs on load momentarily bump the key (enrichener) to see if the added fuel makes any improvement. If yes, then start checking into the accel pump and injectors. I'm assuming this is a 4 cyl 2+2 model.

If the added fuel makes NO difference then DVA testing of ignition components is necessary to make sure all are well within tolerances.

 

[anubix00]

Re: No power under load

just for forum reference, it turned out that the bottom 2 needles in the carbeurators were sticking. the problem started intermittenly, but grew to be more consistent. i removed the carbs, and replaced the needles, and everything runs great.

 

[Gonafixit]

Re: No power under load

aunubix00,
I had the exact same problem yesterday on my 2000 Mercury V200. I rebuilt entire powerhead,carbs,fuel pump, etc in late winter. First time out in spring, everything great, motor sounded great, but a little hard to start after sitting over night. I was thinking or timing, but all seems good. Then yesterday, the motor did the exactly as you discribed your problem. It is as if it is running with a carb or two missing after just getting up on plane.
I assme you are talking about the float needles, right? and did you change the seats?
I was thinking that I put the entire re-build kit on the carbs, but actually, I only did the gastket set for each. I know that I cleaned them meticulously, but I'm thiniking the float needles make a lot of sense. Thanks for following up on the repair.