2003 MFS25A stuck in limp mode (I think)

[Tohatsuguy9]

I hit a stump in the river going about 30MPH and the motor kicked up violently, came back down and I proceeded to haul butt down the river. Two mins later, my boat died and took about 2 mins to start up again. I hit the throttle and the motor shook as RPM’s seem to be 2,000 or less. I ran out of gas about 300yds from boat dock and used trolling motor to get back. I started by changing the the plugs, fuel filter and cleaning all the carbs, jets were all clear. Checked fuel lines and tank. I have almost replaced everything on this Motor and still no luck. All three ignition coils, oil pressure sensor, rectifier (it was and still is getting very hot the rectifier did not get this hot before) CDI, alternator and pulser coils, tried unplugging temp sensor (didn’t work). After replacing all these things, I put a whole new set of plugs in because they were EXTREMELY fouled after maybe 20 mins of combined testing time. Top two we’re almost completely Burt third (bottom) plug was very dark but the contacts were clean so I am assuming it is the only cylinder that is firing. After testing for no more than thirty minutes, I checked my oil dip stick and oil squirted out uncontrollably, not sure why. The oil smelled heavily of gasoline. It idles GREAT and runs strong and sounds great with muffs. I put it in gear with muffs and it sounds like a race car, as soon as it hits any water (load) it seems to jump into what I am calling limp mode. Please help I am out of ideas (and mostly money lol)

 

[pvanv]

Check to see if the fuel pump is dumping gas into the crankcase.

 

[Tohatsuguy9]

Awesome I will look! Would this cause the limp mode?

 

[pvanv]

Would overfill crankcase. No limp mode on these.

 

[Tohatsuguy9]

Awesome I will look! Would this cause the limp mode?

 

[Tohatsuguy9]

Got it thanks! Checked the fuel pump, it didn’t seem to be dumping excessive gas into the crank case. I took it off the mounting brackets, squeezed the bulb and all the gas went to the hose that connected to the carbs as it should. I Repeated the process pressing the back of the fuel pump that goes into crank case and Yielded the same results. Changed the oil to make sure all the gas was gone. I will test it out and post results.

 

[Tohatsuguy9]

This whole time I thought it was a limp mode. Would having to much fluid in the crank case cause the low RPM’s?

 

[Tohatsuguy9]

Changed all the fluids, took her to the river and I was presented with a whole new problem. Before the oil change, it would not exceed 2,000 RPM and would not put the boat on plane, now it is acting like the carbs are clogged. It dies after I give it gas. When I put it in gear, it tries to die and I give it full throttle and it doesn’t rev up at all. Almost as if it were just idling?????

 

[pvanv]

This whole time I thought it was a limp mode. Would having to much fluid in the crank case cause the low RPM’s?

Yes. Common.

 

[pvanv]

If you had that much gas in the oil, either the pump was bad (apparently not) or you arer flooding. That would also account for the fouled plugs.

 

[Tohatsuguy9]

Got it. I ordered new fuel pump. I will keep updating the results. Thanks for replying to my nonsense.

 

[Tohatsuguy9]

Random update, I was running it in my driveway with muffs to get some SeaFoam through it and decided to pull the plugs one by one. I pulled the first plug and the motor died completely. I plugged it back in, started it and pulled plug#2 and 3 individually.. each plug was definitely sparking and caused the motor to drop slightly in idle. Now I am wondering if it is running on only one cylinder and if so why?

 

[pvanv]

Go through the carbs again. Seafoam is just mineral spirits, so don't waste your time on it.

 

[Tohatsuguy9]

Awesome I will look at the carbs again. Fuel pump gets here Monday so I will update then! Thanks for your help Mr. Paul!!

 

[Tohatsuguy9]

Could the fuel pump be pumping too much fuel into the carbs?

 

[pvanv]

No. But the carbs can have problems.

 

[Tohatsuguy9]

I replaced the fuel pump went through the carbs and the original problem still occurred. Engine fired up first crank put it in Forward and no power. Wouldn’t put the boat on a plane.

 

[km1125]

Could the fuel pump be pumping too much fuel into the carbs?

It can't really do that unless the carb needs work. If the needle and seat are messed up or the float doesn't actually float anymore, then that would leave the float bowl open to the flow from the pump. If they are working correctly then they shut off the flow from the pump when the level is correct in the bowl.

 

[Tohatsuguy9]

I did notice that top carb and bottom carb had gas in the bowl, the second (middle carb) was completely dry. Looked like gas hadn’t made it into it in ages.

 

[Tohatsuguy9]

The third carbs pilot Jet looked ever so slightly gunked up but I didn’t think much if it because there was a little daylight.